Interdependent systems providing water and energy services are necessary for agriculture. Climate change and increased resource demands are expected to cause frequent and severe strains on these systems. Arizona is especially vulnerable to such strains due to its hot and arid climate. However, its climate enables year-round agricultural production, allowing Arizona to supply most of the country's winter lettuce and vegetables. In addition to Phoenix and Tucson, cities including El Paso, Las Vegas, Los Angeles, and San Diego rely on Arizona for several types of agricultural products such as animal feed and livestock, meaning that disruptions to Arizona agriculture also disrupt food supply chains to at least six major cities. Arizona's predominately irrigated agriculture relies on water imported through an energy intensive process from water-stressed regions. Most irrigation in Arizona is electricity powered, so failures in energy or water systems can cascade to the food system, creating a food-energy-water (FEW) nexus of vulnerability. We construct a dynamic simulation model of the FEW nexus in Arizona to assess the potential impacts of increasing temperatures and disruptions to energy and water supplies on crop irrigation requirements, on-farm energy use, and yield. We use this model to identify critical points of intersection between energy, water, and agricultural systems and quantify expected increases in resource use and yield loss. Our model is based on threshold temperatures of crops, USDA and US Geological Survey data, Arizona crop budgets, and region-specific literature. We predict that temperature increase above the baseline could decrease yields by up to 12.2% per 1degC for major Arizona crops and require increased irrigation of about 2.6% per 1degC. Response to drought varies widely based on crop and phenophase, so we estimate irrigation interruption effects through scenario analysis. We provide an overview of potential adaptation measures farmers can take, and barriers to implementation.
The environmental and economic impacts of electric vehicles are highly dependent on different types of temporal and spatial variations, including (but not limited to) electricity generation source, driving patterns and conditions, and fuel prices. This study explores the suitability of battery electric vehicles (BEVs) in each state in the U.S. by considering state-specific variations in electricity generation profiles, operation costs, and potential market shares, given current government policies and the social acceptability of the BEVs. This analysis presents a comparative performance assessment of each state and identifies major policy areas to focus on so as to increase suitability of BEVs. To address state-specific inefficiencies towards adoption of BEVs, a novel multi-criteria decision-making framework is developed by integrating Life Cycle Assessment, Data Envelopment Analysis, and Agent Based Modeling. To this end, the environmental and economic impacts of electric vehicles are calculated based on three scenarios: an average electricity generation mix, a marginal electricity generation mix, and an extreme scenario with a 100% solar electricity generation mix. The state-specific water consumption/withdrawal rates and operation costs of BEVs are taken into consideration, as well as their state-specific carbon and energy footprints. The results reveal how different states can utilize their potential of minimizing the negative impacts of transportation by adopting BEVs. While some states are either already successful or currently unsuitable for a widespread adoption of BEVs, some are lagged behind their potential of utilizing more BEVs. The results of this study can be useful for advancing transportation policies by providing a framework for multi-criteria decision analyses in the future. In addition, policy makers can evaluate the relative performance of BEVs compared to states that have already more successfully implemented policies aimed at promoting widespread adoption of BEVs.
Climate change could significantly affect consumer demand for energy in buildings, as changing temperatures may alter heating and cooling loads. Warming climates could also lead to the increased adoption and use of cooling technologies. We assess residential electricity and natural gas demand in Los Angeles, California under multiple climate change projections and investigate the potential for energy efficiency to offset increased demand. We calibrate residential energy archetypes against metered data, accounting for differences in building materials and appliances. Under temperature increases, we find that without policy intervention, residential electricity demand could increase by as much as 41-87% between 2020 and 2060. However, aggressive policies aimed at upgrading heating/cooling systems and appliances could result in electricity use increases as low as 28%, potentially avoiding the installation of new generation capacity. We therefore recommend aggressive energy efficiency, in combination with low-carbon generation sources, to offset projected increases in residential energy demand
The leading source of weather-related deaths in the United States is heat, and future projections show that the frequency, duration, and intensity of heat events will increase noticeably in the Southwestern US. As the number of extreme heat events rises, there is a dearth of knowledge about how infrastructure could be vulnerable to heat events or could contribute to social vulnerability. To understand how buildings perform in heat and potentially stress people, we estimate how quickly indoor air temperature increases across representative building prototypes in Los Angeles, California and Phoenix, Arizona metro areas when air conditioning is inaccessible. Our prototypes include major classifications and cover current and historical time periods. Building thermal vulnerability is defined as the time elapsed as indoor air temperature warms to a threshold temperature deemed to be unsafe based on morbidity and mortality data. Building age and geometry are found to be the strongest indicators of vulnerability. Older neighborhoods in Los Angeles and Phoenix (often more centrally located in the metropolitan areas) are found to contain the buildings whose interiors warm the fastest, raising particular concern because these regions are also forecast to experience temperature increases. Buildings in only 15% of census tracts in Los Angeles and 61% of census tracts in Phoenix warm to over 90°F (32°C) in less than 48 hours of extreme heat. To combat infrastructure vulnerability and provide heat refuge for residents, incentives should be adopted to strategically retrofit buildings where both socially vulnerable populations reside and increasing temperatures are forecast.
Nanocomposite sorbents are an emerging technology for drinking water treatment of multiple pollutants. Here we used anticipatory life cycle assessment to proactively inform sustainable development by comparing synthesis methods and treatment options, identifying critical steps in deployment, and reducing the environmental and human health impacts such that the nanocomposite sorbents become favorable over the existing technology of using two different materials in a mixed bed (MB). We studied iron (hydr)oxide or titanium dioxide nanoparticles precipitated in an anion exchange resin (Fe-AX and Ti-AX) for targeted removal of chromium and arsenic from drinking water. The Ti-AX had the lowest environmental and human health impacts compared to Fe-AX and MB for nine TRACI (Tool for the Reduction and Assessment of Chemical and Environmental Impacts) categories. The synthesis phase for each sorbent contributed 50% – 100% of the total impacts. The greatest opportunity to improve Ti-AX synthesis was reducing oven heating time for nanoparticle hydrolysis. Reducing from 24 to 4 hours had only a small loss in sorbent capacity but reduced impacts by 3%– 31%. Fe-AX synthesis was improved by increasing pollutant removal capacity to require less sorbent to treat the functional unit. This reduced impacts by 26%–42%, making it favorable or equal with MB for six of nine categories. Future development of nanocomposite sorbent synthesis methods should focus on optimizing sorbent capacity, decreasing heating energy demand, and efficiently reusing metal precursors and solvents. This study showed that benefits of treating drinking water involve environmental and human health tradeoffs, and that impacts associated with treatment are on the same order of magnitude as distribution pressurization.
In the United States public transit utilization has increased significantly in the last decade and is considered a critical component in reducing energy use and greenhouse gas emissions in urban areas. Despite public transit’s climate change mitigation potential, the use of transit necessitates environmental exposure which may be a health hazard during periods of extreme heat. Transit system design, which includes stop location and schedules, is shown to contribute to environmental exposure resulting from access and waiting. Using Los Angeles Metro (Los Angeles County, CA) and Valley Metro (Maricopa County, AZ) as case studies of systems operating in extreme heat conditions, the research demonstrates how system design contributes to heat exposure times that vary significantly between neighborhoods. Household level access (walking) time estimates are developed using a shortest path algorithm to nearby transit stops. Waiting time estimates for individual transit stops are derived from published transit schedules and on-board survey responses. The results show that transit users from areas with low residential density, limited high capacity roadways and irregular street networks, and not located along direct paths between major activity centers are likely to experience prolonged access and/or waiting times. Public transit may help mitigate climate change impacts but transit proponents, agencies and planners should be cognizant of the impact an uncertain climate future may have on a growing base of transit riders. These insights can allow us to proactively govern and adapt transit systems to protect people from a growing health concern.
Access to air conditioned space is critical for protecting urban populations from the adverse effects of heat exposure. Yet there remains fairly limited knowledge of penetration of private (home air conditioning) and distribution of public (cooling centers and commercial space) cooled space across cities. Furthermore, the deployment of government-sponsored cooling centers is not based on the location of existing cooling resources (residential air conditioning and air conditioned public space), raising questions of the equitability of access to heat refuges. Using Los Angeles County, California and Maricopa County, Arizona (whose county seat is Phoenix) we explore the distribution of private and public cooling resources and access inequities at the household level. We do this by evaluating the presence of in-home air conditioning and developing a walking-based accessibility measure to air conditioned public space using a combined cumulative opportunities-gravity approach. We find significant inequities in the distribution of residential air conditioning across both regions which are largely attributable to building age and inter/intra-regional climate differences. There are also regional disparities in walkable access to public cooled space. At average walking speeds, we find that official cooling centers are only accessible to a small fraction of households (3% in Los Angeles, 2% in Maricopa) while a significantly higher number of households (80% in Los Angeles, 39% in Maricopa) have access to at least one other type of public cooling resource which includes libraries and commercial establishments. Aggregated to a neighborhood level, we find that there are areas within each region where access to cooled space (either public or private) is limited which may increase the health risks associated with heat.
Life Cycle Assessment (LCA) and Urban Metabolism (UM) are popular approaches for urban system environmental assessment. However, both approaches have challenges when used across spatial scales. LCA tends to decompose systemic information into micro-level functional units that mask complexity and purpose, while UM typically equates aggregated material and energy flows with impacts and is not ideal for revealing the mechanisms or alternatives available to reduce systemic environmental risks. This study explores the value of integrating UM with LCA, using vehicle transportation in the Phoenix metropolitan area as an illustrative case study. Where other studies have focused on the use of LCA providing upstream supply chain impacts for UM, we assert that the broader value of the integrated approach is in i) the ability to cross scales (from micro to macro) in environmental assessment, and ii) establishing an analysis that captures function and complexity in urban systems. The results for Phoenix show the complexity in resource supply chains and critical infrastructure services, how impacts accrue well beyond geopolitical boundaries where activities occur, and potential system vulnerabilities.
Climate change may constrain future electricity supply adequacy by simultaneously reducing electric transmission capacity and increasing electricity demand. This study estimates potential climate impacts to electric transmission capacity and peak electricity load in the United States using downscaled global climate model (GCM) projections. Electric power cables suffer decreased transmission capacity under hotter ambient air temperatures; similarly, during the summer peak period, electricity demand typically increases with hotter air temperatures due to increased cooling loads. As atmospheric carbon concentrations increase, higher ambient air temperatures may strain power infrastructure by simultaneously reducing transmission capacity and increasing peak electricity demand. Taken together, these coincident impacts may adversely affect electric power supply adequacy. We estimate the impacts of climate change on both the rated capacity of transmission infrastructure and expected electricity demand for 1,044 electrical utilities across the United States. We estimate climate-attributable capacity reductions to transmission lines by constructing thermal models of representative conductors, then forcing these models with future temperature projections to determine the relative change in rated ampacity. Next, we assess the impact of climate change on electricity demand by using historical relationships between ambient temperature and utility-scale summertime peak load to estimate the extent to which climate change will incur additional peak load increases. We find that by mid-century (2040-2060), climate change may reduce average summertime transmission capacity by 1.9-5.8% relative to the 1990-2010 reference period. At the same time, peak summertime loads may rise by 4.2-15% on average due to increases in ambient air temperature. In the absence of energy efficiency gains, demand-side management programs and transmission infrastructure upgrades, these load increases have the potential to upset current assumptions about future electricity supply adequacy.
Vehicle border crossings between Mexico and the United States generate significant amounts of air pollution, which can pose health threats to personnel at the ports of entry (POEs) as well as local communities. Using the Mariposa POE in Nogales, Arizona as a case study, light-duty and heavy-duty vehicle emissions are analyzed with the objective of identifying effective emission reduction strategies such as inspection streamlining, physical infrastructure improvements, and fuel switching. Historical vehicle volumes as well as field data were used to establish a simulation model of vehicle movement in VISSIM. Four simulation scenarios with varied congestion levels were considered to represent real-world seasonal changes in traffic volume. Four additional simulations captured varying levels of expedited processing procedures. The VISSIM output was analyzed using the EPA's MOVES emission simulation software for conventional air pollutants. For the highest congestion scenario, which includes a 200% increase in vehicle volume, total emissions increase by around 460% for PM2.5 and NOx, and 540% for CO, SO2, GHGs, and NMHC over uncongested conditions. Expedited processing and queue reduction can reduce emissions in this highest congestion scenario by as much as 16% for PM2.5, 18% for NOx, 20% for NMHC, 7% for SO2 and 15% for GHGs and CO. Adoption of some or all of these changes would not only reduce emissions at the Mariposa POE, but would have air-quality benefits for nearby populations in both the US and Mexico. Fleet-level changes could have far-reaching improvements in air quality on both sides of the border.
Electric vehicles are an emerging technology with significant potential for reducing carbon dioxide emissions. Yet strategies to minimize carbon dioxide emissions by strategically charging during different times of day have not been rigorously explored. To identify possibilities for minimizing emissions from plug-in electric vehicle use, daily optimized charging strategies over each electricity reliability region of the United States are explored. Optimized schedules of plug-in electric vehicle charging for standard and vehicle-to-grid use were compared with pre-timed charging schedules to characterize the potential for carbon dioxide emission reductions across charging characteristics, regional driving, and marginal energy generation trends. It was found that optimized charging can reduce carbon dioxide emissions over pre-timed charging by as much as 31% for standard use and 59% for vehicle-to-grid use. However, some scenarios of vehicle-to-grid participation were found to increase carbon dioxide emissions by up to 396 g carbon dioxide per mile by displacing stored energy from more carbon-intense energy generation periods. Results also indicate that plug-in electric vehicle charging emissions can vary widely for a given energy efficiency rating. Current energy efficiency ratings may lead to incorrect assumptions of plug-in electric vehicles emissions compared to conventional gasoline vehicles due to varying regional and temporal emissions. To coincide with the push for lower greenhouse gas emissions from transportation, charging times for plug-in electric vehicles should target periods where charging promotes carbon dioxide reductions, and electric vehicle energy efficiency ratings should be reconsidered in order to promote sustainable plug-in electric vehicle use moving forward.
In an extreme heat event, people can go to air-conditioned public facilities if residential air-conditioning is not available. Residences that heat slowly may also mitigate health effects, particularly in neighborhoods with social vulnerability. We explored the contributions of social vulnerability and these infrastructures to heat mortality in Maricopa County and whether these relationships are sensitive to temperature. Using Poisson regression modeling with heat-related mortality as the outcome, we assessed the interaction of increasing temperature with social vulnerability, access to publicly available air conditioned space, home air conditioning and the thermal properties of residences. As temperatures increase, mortality from heat-related illness increases less in census tracts with more publicly accessible cooled spaces. Mortality from all internal causes of death did not have this association. Building thermal protection was not associated with mortality. Social vulnerability was still associated with mortality after adjusting for the infrastructure variables. To reduce heat-related mortality, the use of public cooled spaces might be expanded to target the most vulnerable.
Current life cycle assessment (LCA) interpretation practices typically emphasize hotspot identification and improvement assessment. However, these interpretation practices fail in the context of a decision-driven comparative LCA where the goal is to select the best option from a set of dissimilar alternatives. Interpretation of comparative LCA results requires understanding of the trade-offs between alternatives—instances in which one alternative performs better or worse than another—to identify the environmental implications of a specific decision. In this case, analysis must elucidate relative trade-offs between decision alternatives, rather than absolute description of the alternatives individually. Here, typical practices fail. This article introduces a probability distribution-based approach to assess the significance of performance differences among alternatives that allows LCA practitioners to focus analyses on those aspects most influential to the decision, identify the areas that would benefit the most from data refinement given the level of uncertainty, and complement existing hotspot analyses. In a case study of a comparative LCA of five photovoltaic technologies, findings show that thin-film cadmium telluride and amorphous silicon cell panels are most likely to perform better than other alternatives. Additionally, the impact categories highlighted by the new approach are different than those highlighted by typical external normalization practices, suggesting that a decision-driven approach to interpretation would redirect environmental research efforts.
Heat vulnerability of urban populations is becoming a major issue of concern. The American Southwest is predicted to experience greater numbers of heat days as well as significant impacts to water supply due to climate change impacts. We point to the importance of coupled socio technical system analysis to understand how people maybe be impacted by heat and how these systems themselves may structure unequal exposure to heat impacts and result in vulnerability. We suggest it is important to go beyond examining urban heat island effects to a broader scale of analysis that includes power systems and their need for water, urban morphology (e.g. buildings, access to cooling centers, parks, open space and surface albedo), and vulnerable populations. Rules, regulations, codes all structure the urban environment (street widths, building insulation, location of cooling centers and so forth) and form the social regulatory side of the socio technical system. The rules and regulations are manifest in the hard infrastructures, or technical systems, that then create the built environment, pipes, wires and power supply. Together they structure the socio technical system that may have significant unequal impacts on human populations. In this case we discuss the impacts of a warming climate in the Southwest United States and the potential implications for vulnerable populations.
Within residential electricity consumption there exists significant variability from home to home due to the differences in the thermal properties of buildings, appliances used, and activities of the inhabitants. Electricity analyses at sub-city scales that use predefined geographies, such census tracts, might artificially split areas that have homogenous socio-technical characteristics and thus different patterns of electricity consumption. We investigate the spatial relationships between demographic variables, types of buildings, and electricity consumption by forming new geographies for residential building energy use with a max-p clustering algorithm. Using Los Angeles and New York City as case studies, we compare the differences in variability in energy use within predefined geographies (e.g., census tract) and geographies defined by clustering on socio-technical characteristics. We find that using a socio-technical clustering approach, regardless of the chosen subset of variables, reduces the variability over pre-defined geopolitical boundaries with high statistical significance. By defining geospatial regions of energy analysis, we reduce intra-regional variability by 13% in Los Angeles and 29% in New York, thereby improving opportunities for prediction and forecasting. To our knowledge, this is the first study to examine the role of spatial boundaries in urban energy assessment. The creation of socio-technical geographies for building electricity assessment creates opportunities for improving predictions and forecasts for future sub- and cross-city energy studies.
As local governments plan to expand airport infrastructure and build air service, monetized estimates of damages from air pollution are important for balancing environmental impacts. While it is well known that aircraft emissions near airports directly affect nearby populations, it is less clear how the airport-specific aircraft operations and impacts result in monetized damages to human health and the environment. We model aircraft and ground support equipment emissions at major US airports and estimate the monetized human health and environmental damages of near airport (within 60 miles) emissions. County-specific unit damage costs for PM, SOx, NOx, and VOCs and damage valuations for CO and CO2 are used along with aircraft emissions estimations at airports to determine impacts. We find that near-airport emissions at major US airports caused a total of $1.9 billion in damages in 2013, with airports contributing between $720 thousand and $190 million each. These damages vary by airport from $1 to $9 per seat per one-way flight and costs per passenger are often greater than airport landing fees. As the US aviation system grows, it is possible to minimize human and environmental costs by shifting airplane technologies and expanding service into airports where fewer impacts are likely to occur.
Passenger and freight transport are one of the world’s leading contributors of anthropogenic carbon dioxide and other greenhouse gas (GHG) emissions. It has been suggested that the world can reduce the GHG-intensity of the transportation sector in the future through the adoption of new fuel-saving technologies, switching demand between modes, and large-scale implementation of alternative fuels. The future scenarios presented in this study assess the GHG reduction potentials of policies related to these three strategies for major passenger and freight modes across 8 regions of the world. We find that new fuel-saving technologies can significantly reduce the life-cycle GHG footprint of both passenger and freight vehicles. However, this improved fuel efficiency has negative feedbacks to the effectiveness of mode-switching and alternative fuel adoption policies through 2050. Our results suggest that improvements in the fuel efficiency of vehicles alone may cause the marginal benefits of GHG abatement policies to diminish over time. However, this trend may be opposite if the rate at which alternative fuel pathways decarbonize at faster rates than conventional transportation fuels (e.g., petroleum based). Overall, we find that the largest opportunities for GHG reductions occur in non-OECD countries. Given the many factors that distinguish transportation systems within these countries from the rest of the world (e.g., individual access to financial resources, control over infrastructure, systems to maintain new technologies, etc.), many benefits could be gained through interregional cooperation
Emissions assessment of goods movement should include local and remote life-cycle effects as well as barriers for mode shifting to effectively reduce future impacts. Using uni- and multi-modal freight movements by truck, rail, and ocean-going vessel within California, a life-cycle assessment is developed to estimate the local and remote emissions that occur from freight activity associated with the state and the potential for reducing emissions for legislated goals. California Assembly Bill 32 calls for a greenhouse gas emission reduction of 3.5 million tonnes from the goods movement sector by 2020. Long-run average mode-specific results show that ocean going vessels emit the fewest emissions per tonne-km of shipment, followed by rail, then by trucks, and that the inclusion of life-cycle processes can increase impacts by up 36% for energy and GHG emissions and by over 5,000% for conventional air pollutants. Efforts to reduce emissions by mode shifting should recognize that infrastructure and market configurations may preclude the substitution of one mode for another. A uni- and multi-modal shipping emissions assessment is developed for intrastate and California-associated freight movements to illustrate the life-cycle impacts of typical trips for certain types of goods. The trip-based assessment shows how emissions are the result of activities that span multiple geopolitical boundaries. When targeting greenhouse gas reductions in California it should be recognized that heavy-duty trucks are responsible for 98% of emissions within the state and little opportunity exists to shift freight to other modes. Thus, an assessment of future freight truck technology improvements is performed to estimate effective strategies to meet 2050 greenhouse gas reduction goals. Emission reductions are found to be most-sensitive to fuel economy, rather than the rate of adoption of alternative fuel vehicles. One future scenario, where a new hybrid-electric truck fleet is adopted over 35 years and experiences an aggressive 6% annual fuel economy increase produces emission reductions that are 82% below the projected business-as-usual emissions, thereby meeting long-term climate goals for the freight sector.
The environmental impacts and economic costs associated with passenger transportation are the result of complex interactions between people, infrastructure, urban form and underlying activities. When it comes to roadway infrastructure, the ongoing resource commitments (which can be measured as embedded impacts) enables vehicle travel which is a dominant source of air emissions in regional inventories. The relationship between infrastructure and the environmental impacts it enables are not often considered dynamic. Furthermore, the environmental impacts of roadway infrastructure are typically assessed at a fine geospatial and temporal scale (i.e., a short distance of roadway over a short period of time) and there is generally poor knowledge of how the growth of a roadway network over time creates a need for long-term maintenance commitments that create environmental impacts and lock-in vehicle travel. A framework and operational life-cycle assessment (LCA) tool (City Road Network (CiRN) LCA) are developed to assess the extent to which roadway commitments result in ongoing and increasing environmental and economic impacts. Known for its extensive road network and automobile reliance, Los Angeles County is used as a case study to explore the relationship between historic infrastructure deployment decisions and the emergent behavior of vehicle travel. The results show that every kilogram of greenhouse gas emissions (GHG) resulting from construction and maintenance has led to 47 kg of GHG emissions in fuel combustion. Similarly, every public dollar invested into the network has created $126-288 in private user spending. As states and regions grapple with financing the upkeep of aging infrastructure, a solid understanding of the relationship between upfront infrastructure capital costs, long-term maintenance costs, and associated long-term environmental effects are critical. In Los Angeles, the infrastructure that exists was largely deployed by 1987. Since then, maintenance costs are estimated to have exceeded city budgets despite minimal growth in infrastructure. The research demonstrates how infrastructure matures (i.e., its stages of growth towards completion), it becomes locked-in leading to transitions from a capital financing focus to foci on securing rehabilitation and maintenance costs, and the share of environmental impacts changing from being somewhat balanced between embedded infrastructure construction impacts and vehicle use to today where vehicle use creates impacts several orders of magnitude greater than those associated with rehabilitation.
As decision-makers increasingly embrace life-cycle assessment (LCA) and target transportation services for regional environmental goals, it becomes imperative that outcomes from changes to complex systems are accurately communicated. California’s greenhouse gas (GHG) reduction policies have created interest in better understanding how public transit systems reduce emissions. An LCA is developed of the Los Angeles Expo line and a competing car trip that includes vehicle, infrastructure, and energy production processes, in addition to propulsion. Energy use, GHG emissions, and the potential for photochemical smog formation and respiratory impacts are assessed. When results are normalized per passenger kilometer traveled (PKT), life-cycle processes increase impacts by up to 83% for energy use and GHG emissions, and up to 690% for smog and respiratory impact potentials. However, the use of a non-time-based PKT normalization obfuscates a decision-maker’s ability to understand whether the deployment of a transit system reduces emissions below a future year policy target (e.g., 80% of 1990 emissions by 2050). The year-by-year marginal effects of the decision to deploy the Expo line are developed including reduction in automobile travel. The time-based marginal results provide clearer explanations for how environmental effects in a region change and the critical life-cycle processes that should be targeted to achieve policy targets. The line can be expected to breakeven on GHG emissions within two decades but its ability meet long-run policy targets is most sensitive to infrastructure construction emissions, mode shifting, a changing electricity mix, and improving automobile fuel economy.
Many cities have adopted minimum parking requirements but we have relatively poor information about how parking infrastructure has grown. We estimate how parking has grown in Los Angeles County from 1900 to 2010 and how parking infrastructure evolves, affects urban form, and relates to changes in automobile travel, using building and roadway growth models. We find that since 1975 the ratio of residential offstreet parking spaces to automobiles in Los Angeles County is close to 1.0 and the greatest density of parking spaces is in the urban core while most new growth in parking occurs outside of the core. 14% of incorporated land in Los Angeles County is committed to parking. Uncertainty in our space inventory is attributed to our building growth model, onstreet space length, and the assumption that parking spaces were created as per the requirements.
The continued use of minimum parking requirements is likely to encourage automobile use at a time when metropolitan areas are actively seeking to manage congestion and increase transit use, biking, and walking. Widely discussed ways to reform parking policies may be less than effective if planners do not consider the remaining incentives to auto use created by the existing parking infrastructure. Planners should encourage the conversion of existing parking facilities to alternative uses.
Cities are increasingly developing greenhouse gas (GHG) mitigation plans and reduction targets based on a growing body of knowledge about climate change risks, and changes to passenger transportation are often at the center of these efforts. Yet little information exists for characterizing how quickly or slowly GHG emissions reductions will accrue given changes in urban form around transit, and whether benefits will accrue quickly enough to meet policy year targets (such as reaching 20% of 1990 GHG emissions levels by 2050). Even more complicated is when cities focus on achieving GHG reductions through integrated transportation and land use planning, as changes in emissions can occur across many sectors (such as transportation, building energy use, and electricity generation). Using the Los Angeles Expo line, a framework is developed to assess how financing schemes change the rate of redevelopment and resulting life-cycle GHG emissions from travel and building energy use. The framework leverages an integrated transportation and land use life-cycle assessment model that captures upfront construction of new development near transit and the long-term changes in household energy use for travel and buildings. The results show that for the same amount of development around the Expo line it is possible to either meet (if aggressive redevelopment happens early) or not meet (if redevelopment starts decades out) state GHG goals by 2050. The time-based approach reveals how specific redevelopment schedules are needed for a city to reduce GHG emissions at a rate that meets future targets.
Cities need to understand and manage their carbon footprint at the level of streets, buildings and communities, urge Kevin Robert Gurney and colleagues.
As California establishes its greenhouse gas emissions cap-and-trade program and considers options for using the new revenues produced under the program, the public and decision-makers have access to tenuous information on the relative cost-effectiveness of passenger transportation investment options. Towards closing this knowledge gap, the cost-effectiveness of greenhouse gas reductions forecast from High-Speed Rail are compared with those estimated from recent urban transportation projects (specifically light rail, bus rapid transit, and a bicycling/pedestrian pathway) in California. Life-cycle greenhouse gas emissions are joined with full cost accounting to better understand the benefits of cap-and-trade investments. Results are largely dependent on the economic cost allocation method used. Considering only public subsidy for capital, none of the projects appear to be a cost-effective means to reduce greenhouse gas emissions (i.e., relative to the current price of greenhouse gas emissions in California’s cap-and-trade program at $11.50 per tonne). However, after adjusting for the change in private costs users incur when switching from the counterfactual mode (automobile or aircraft) to the mode enabled by the project, all investments appear to reduce greenhouse gas emissions at a net savings to the public. Policy and decision-makers who consider only the capital cost of new transportation projects can be expected to incorrectly assess alternatives and indirect benefits (i.e., how travelers adapt to the new mass transit alternative) should be included in decision-making processes.
This manuscript supersedes our UCLA Institute of Transportation Studies report Cost-Effectiveness of Reductions in Greenhouse Gas Emissions from California High-Speed Rail and Urban Transportation Projects.
At the core of the intensifying debate over LCA modeling of the environmental impacts of biofuels is doubt that biofuels can mitigate climate change. Two types of LCA, attributional and consequential, have been applied to answer this question with competing results. These results turn on system boundary design, including feedstock considerations and assumptions of indirect land-use impacts. The broadening of the system boundary to include large scale land-use change of biofuel production has challenged the viability of biofuels to meet climate change goals. This paper reviews some of the latest literature in biofuels LCA exemplary of this debate, and discusses the distinctions between attributional and consequential models in biofuels. We also present a generalized boundary map that can be used to convey LCA system boundaries clearly and succinctly within both attributional and consequential LCA
As new transportation technologies, travel patterns, and fuels emerge there is opportunity to proactively assess environmental impacts to ensure that reductions occur and unintended tradeoffs are avoided. This article summarizes the goals, scope, and findings of a special issue on Transportation Sustainability. The special issue provides an overview of recent research and policies on autonomous vehicles, electric vehicles, on-demand mobility (including carsharing), intelligent transportation systems, and biofuels, and their expected environmental effects. The reviews show that there are efforts underway to understand the environmental impacts of changes in transportation systems that may lead to technology designs and deployment strategies for environmental sustainability
Building stocks constitute enduring components of urban infrastructure systems, but little research exists on their residence time or changing environmental impacts. Using Los Angeles County, California as a case study, a framework is developed for assessing the changes of building stocks in cities (i.e., a generalizable framework for estimating the construction and deconstruction rates), the residence time of buildings and their materials, and the associated embedded environmental impacts. In Los Angeles, previous land use decisions prove not easily reversible, and past building stock investments may continue to constrain the energy performance of buildings. The average age of the building stock has increased steadily since 1920, and more rapidly after the post-WWII construction surge in the 1950s. Buildings will likely endure for 60 years or longer, making this infrastructure a quasi-permanent investment. The long residence time, combined with the physical limitations on outward growth, suggests that the Los Angeles building stock is unlikely to have substantial spatial expansion in the future. The construction of buildings requires a continuous investment in material, monetary, and energetic resources, resulting in environmental impacts. The long residence time of structures implies a commitment to use and maintain the infrastructure, potentially creating barriers to an urban area’s ability to improve energy efficiency. The immotility of buildings, coupled with future environmental goals, indicates that urban areas will be best positioned by instituting strategies that ensure reductions in life-cycle (construction, use, and demolition) environmental impacts..
Project website: www.urbantransitions.org/losangelesgrowth/
Climate change may constrain future electricity generation capacity by increasing the incidence of extreme heat and drought events. We estimate reductions to generating capacity in the Western United States based on long-term changes in streamflow, air temperature, water temperature, humidity and air density. We simulate these key parameters over the next half century by joining downscaled climate forcings with a hydrologic modeling system. For vulnerable power stations (46% of existing capacity), climate change may reduce average summertime generating capacity by 1.1-3.0%, with reductions of up to 7.2-8.8% under a ten-year drought. Currently, power providers do not account for climate impacts in their development plans, meaning that they could be overestimating their ability to meet future electricity needs.
Metropolitan greenhouse gas and air emissions inventories can better account for the variability in vehicle movement, fleet composition, and infrastructure that exists within and between regions, to develop more accurate information for environmental goals. With emerging access to high quality data, new methods are needed for informing transportation emissions assessment practitioners of the relevant vehicle and infrastructure characteristics that should be prioritized in modeling to improve the accuracy of inventories. The sensitivity of light and heavy-duty vehicle greenhouse gas (GHG) and conventional air pollutant (CAP) emissions to speed, weight, age, and roadway gradient are examined with second-by-second velocity profiles on freeway and arterial roads under free-flow and congestion scenarios. For GHG and CAP upper and lower bounds of each factor show the potential variability which could exist in emissions assessments across U.S. cities. When comparing the effects of changes in these characteristics across U.S. cities against average characteristics of the U.S. fleet and infrastructure, significant variability in emissions is found to exist. GHGs from light-duty vehicles could vary by -2%-11% and CAP by -47%-228% when compared to the baseline. For heavy-duty vehicles the variability is -21%-55% and -32%-174%, respectively. The results show that cities should more aggressively pursue the integration of emerging big data into regional transportation emissions modeling, and the integration of these data is likely to impact GHG and CAP inventories and how aggressively policies should be implemented to meet reductions. A web-tool (available at www.transportationlca.org/urbanemissions) is developed to aide cities in improving emissions uncertainty.
The expected urbanization of the planet in the coming century coupled with aging infrastructure in developed regions, increasing complexity of man-made systems, and pressing climate change impacts have created opportunities for reassessing the role of infrastructure and technologies in cities and how they contribute to greenhouse gas (GHG) emissions. Modern urbanization is predicated on complex, increasingly coupled infrastructure systems, and energy use continues to be largely met from fossil fuels. Until energy infrastructures evolve away from carbon-based fuels, GHG emissions are critically tied to the urbanization process. Further complicating the challenge of decoupling urban growth from GHG emissions are lock-in effects and interdependencies. This paper synthesizes state-of-the-art thinking for transportation, fuels, buildings, water, electricity, and waste systems and finds that GHG emissions assessments tend to view these systems as static and isolated from social and institutional systems. Despite significant understanding of methods and technologies for reducing infrastructure-related GHG emissions, physical, institutional, and cultural constraints continue to work against us, pointing to knowledge gaps that must be addressed. This paper identifies seven challenges to improve our understanding of the role of infrastructure and technologies during urban development and positioning these increasingly complex systems for low-carbon growth in both high-income and low- to middle-income regions. The challenges emphasize how we reimagine the role of infrastructure in the future and how people, institutions, and ecological systems interface with infrastructure.
Carbon capture and storage (CCS) for coal power plants reduces carbon dioxide emissions, but also affects other air emissions on and offsite. This research assesses the net societal benefits and costs of Monoethanolamine (MEA) CCS, valuing changes in supply chain emissions of CO2, SO2, NOX, NH3 and particulate matter (PM). Geographical variability and stochastic uncertainty for 407 coal power plant locations in the U.S. are analyzed. The main result is that the net environmental benefits and costs of MEA CCS depend critically on location. For a few favorable sites of power plant and upstream processes, CCS realizes a net benefit (benefit-cost ratio > 1) if the social cost of carbon exceeds $51/ton. For much of the U.S. however, the social cost of carbon must be much higher to realize net benefits from CCS, up to $910/ton. While the social costs of carbon are uncertain, typical estimates are in the range of $33-221/ton, much lower than the threshold value for many potential CCS locations. The method developed has broad applications to assess geographic variability in benefits of energy technologies.
Independent lines of research on urbanization, urban areas and the carbon cycle have advanced our understanding of some of the processes through which energy and land uses affect carbon. This synthesis paper synthesizes some of these diverse viewpoints as a first step towards a co-produced, integrated framework for understanding urbanization processes, urban areas and their relationships to the carbon cycle. It suggests the need for approaches that complement and combine the plethora of existing insights into interdisciplinary and transdisciplinary explorations of how different urbanization processes, and socio-ecological and technological components of urban areas, affect the spatial and temporal patterns of carbon emissions differentially over time and within and across cities. It also calls for a more holistic approach to examining the carbon implications of urbanization and urban areas based on such interconnected features of urban development pathways as urban form, economic function, economic growth policies and other governance arrangements. It points to a wide array of uncertainties around urbanization processes, including urban socio-institutional and built-environment systems and their impact on the exchange of carbon flows within and outside urban areas. We must also understand in turn how carbon feedbacks, including carbon impacts and potential impacts of climate change, can affect urbanization processes. Finally, the paper explores options, barriers and limits to transitioning to low-carbon urbanization trajectories, and suggests the development of an end-to-end, co-produced and integrated scientific understanding that can more effectively inform the navigation of transitional journeys and the avoidance of obstacles along the way.
Current PV Life Cycle Assessment (LCA) literature rely on past data to quantify the environmental impact of PV technology based on parameters like Energy Return on Investment (EROI), Greenhouse gas (GHG) emissions and Energy Pay Back Time (EPBT). The net environmental benefit of a PV module, influenced by energy intensive manufacturing processes, is allocated at the time of installation. However, the environmental benefits of a PV system do not accrue immediately after installation but accrue over the entire life cycle of the PV module. This inter-temporal trade-off depends on the magnitude of upfront PV manufacturing GHG emissions and the year-on-year GHGs avoided when PV electricity displaces electricity generated from fossil fuels. Moreover, environmental impact assessments of PV systems based on retrospective LCAs precludes the inclusion of four dynamic factors: the choice of PV technology, varying rates of technology improvements for different PV technologies, electricity mixes of the deployment location and location where PV systems are manufactured.
By not incorporating inter-temporal trade-off analysis and dynamic factors that influence net environmental impacts of PV deployments, PV capacity additions can inadvertently become counter-productive by increasing net GHG emissions over the short term. Also, policy makers forgo an opportunity to optimize PV capacity additions for minimal short term GHG impacts. This project designs and implements an optimization model to minimize the short term CRF impacts of PV system deployments by incorporating the inter-temporal trade-offs involved. When integrated with PV LCAs this model can help policy makers to minimize short term impacts along with fulfilling long term GHG reduction goals. The results show that the optimal PV deployment strategy for the three states - California, Wyoming and Arizona - varies depending on the electricity mixes of these states. The optimal PV deployment strategy is sensitive to the state of technology and the choice of PV technology to fulfill the targets. Also, adopting an sub-optimal PV deployment strategy to meet California's PV policy targets by importing Silicon PV modules from China will increase the CO2 emissions over the short term.
The environmental and economic assessment of neighborhood-scale transit-oriented urban form changes should include initial construction impacts through long-term use to fully understand the benefits and costs of smart growth policies. The long-term impacts of moving people closer to transit require the coupling of behavioral forecasting with environmental assessment. Using new light rail and bus rapid transit in Los Angeles, California as a case study, a life-cycle environmental and economic assessment is developed to assess the potential range of impacts resulting from mixed-use infill development. An integrated transportation and land use life-cycle assessment framework is developed to estimate energy consumption, air emissions, and economic (public, developer, and user) costs. Residential and commercial buildings, automobile travel, and transit operation changes are included and a 60-year forecast is developed that compares transit-oriented growth against growth in areas with only predominantly local bus service. The results show that commercial developments create the greatest potential for impact reductions followed by residential commute shifts to transit, both of which may be effected by access to high-capacity transit, reduced parking requirements, and developer incentives. Greenhouse gas emission reductions between 3-540 Gg CO2-equivalents per year can be achieved for as low as $10.50 per tonne. Potential respiratory impacts (PM10-equivalents) and smog formation can be reduced by 26-36%. The shift from business-as-usual growth to transit-oriented development may increase development costs by as much as $610 million, but can decrease user costs by $4,000 per household per year over the building lifetime.
This synthesis article presents an overview of an urban metabolism approach using mixed methods and multiple sources of data to Los Angeles. We examine electric energy use in buildings, GHG emissions from electricity, calculate embedded infrastructure life cycle inputs, water use and solid waste streams in an attempt to better understand the urban flows and sinks in the Los Angeles region (City and County).,. This quantification is being conducted to assist policy-makers better target energy conservation and efficiency programs, pinpoint best locations for distributed solar generation and develop policies for greater sustainability. It provides a framework to which many more UM flows can be added to create greater understanding of the County’s resource dependencies. Going forward, together with policy analysis, UM can help untangle the complex intertwined resource dependencies that cities must address as they attempt to become more sustainable.
Water and energy resources are intrinsically linked, yet they are managed separately-even in the water-scarce American Southwest. This study develops a spatially explicit model of water-energy interdependencies in Arizona and assesses the potential for cobeneficial conservation programs. The interdependent benefits of investments in eight conservation strategies are assessed within the context of legislated renewable energy portfolio and energy efficiency standards. The cobenefits of conservation are found to be significant. Water conservation policies have the potential to reduce statewide electricity demand by 0.82–3.1%, satisfying 4.1–16% of the state’s mandated energy-efficiency standard. Adoption of energy-efficiency measures and renewable generation portfolios can reduce nonagricultural water demand by 1.9–15%. These conservation cobenefits are typically not included in conservation plans or benefit-cost analyses. Many cobenefits offer negative costs of saved water and energy, indicating that these measures provide water and energy savings at no net cost. Because ranges of costs and savings for water-energy conservation measures are somewhat uncertain, future studies should investigate the cobenefits of individual conservation strategies in detail. Although this study focuses on Arizona, the analysis can be extended elsewhere as renewable portfolio and energy efficiency standards become more common nationally and internationally.
The comprehensiveness of environmental assessments of future long-distance travel that include high-speed rail (HSR) are constrained by several methodological, institutional, and knowledge gaps that must and can be addressed. These gaps preclude a robust understanding of the changes in environmental, human health, resource, and climate change impacts that result from the implementation of HSR in the United States. The gaps are also inimical to an understanding of how HSR can be positioned for 21st century sustainability goals. Through a synthesis of environmental studies, the gaps are grouped into five overarching grand challenges. They include a spatial incompatibility between HSR and other long-distance modes that is often ignored, an environmental review process that obviates modal alternatives, siloed interest in particular environmental impacts, a dearth of data on future vehicle and energy sources, and a poor understanding of secondary impacts, particularly in land use. Recommendations are developed for institutional investment in multimodal research, knowledge and method building around several topics. Ultimately, the environmental assessment of HSR should be integrated in assessments that seek to understand the complementary and competitive configurations of transportation services, as well as future accessibility.
Purpose: Comparative Life Cycle Assessments (LCAs) today lack robust methods of interpretation that help decision makers understand and identify tradeoffs in the selection process. Truncating the analysis at characterization is misleading and existing practices for normalization and weighting may unwittingly oversimplify important aspects of a comparison. This paper introduces a novel approach based on a multi-criteria decision analytic method known as Stochastic Multi-attribute Analysis for Life Cycle Impact Assessment (SMAA-LCIA) that uses internal normalization by means of outranking and exploration of feasible weight spaces.
Methods: To contrast different valuation methods, this study performs a comparative LCA of liquid and powder laundry detergents using three approaches to normalization and weighting: (1) characterization with internal normalization and equal weighting, (2) Typical valuation consisting of external normalization and weights, and (3) SMAA-LCIA using outranking normalization and stochastic weighting. Characterized results are often represented by LCA software with respect to their relative impacts normalized to 100%. Typical valuation approaches rely on normalization references, single value weights and utilizes discrete numbers throughout the calculation process to generate single scores. Alternatively, SMAA-LCIA is capable of exploring high uncertainty in the input parameters, normalizes internally by pair-wise comparisons (outranking) and allows for the stochastic exploration of weights. SMAA-LCIA yields probabilistic, rather than discrete comparisons that reflect uncertainty in the relative performance of alternatives.
Results and Discussion: All methods favored liquid over powder detergent. However, each method results in different conclusions regarding the environmental tradeoffs. Graphical outputs at characterization of comparative assessments portray results in a way that is insensitive to magnitude and thus can be easily misinterpreted. Typical valuation generates results that are oversimplified and unintentionally biased towards a few impact categories due to the use of normalization references. Alternatively, SMAALCIA avoids the bias introduced by external normalization references, includes uncertainty in the performance of alternatives and weights, and focuses the analysis on identifying the mutual differences most important to the eventual rank ordering.
Conclusions and recommendations: SMAA is particularly appropriate for comparative LCAs because it evaluates mutual differences and weights stochastically. This allows for tradeoff identification and the ability to sample multiple perspectives simultaneously. SMAA-LCIA is a robust tool that can improve understanding of comparative LCA by decision- or policy-makers.
The architecture-engineering-construction (AEC) industry faces increasing demands on its projects while budgets appear to be shrinking. Building owners and operators seem to want their buildings to do more for less cost. Although this may seem counterintuitive, it aligns nicely with a sustainable-architecture approach of less is more. Moreover, in a shift from exclusively considering first costs for a project, the AEC industry seems to be moving in the direction of life-cycle cost considerations, furthering the opportunity for a more sustainable built environment. Often sustainable is synonymous with achieving certification [e.g., Leadership in Energy and Environmental Design (LEED) and Infrastructure Voluntary Evaluation Sustainability Tool (INVEST) certification]. Whereas the authors acknowledge that certification can improve particular aspects of sustainability, it is necessary to take a broader approach and consider economic, environmental, and social dimensions of sustainability. In this paper, the authors explore each of these dimensions and present examples of how the AEC industry can measure, balance, and monetize them.
The environmental outcomes of urban form changes should couple life-cycle and behavioral assessment methods to better understand urban sustainability policy outcomes. Using Phoenix, Arizona light rail as a case study, an integrated transportation and land use life-cycle assessment (ITLU-LCA) framework is developed to assess the changes to energy consumption and air emissions from transit-oriented neighborhood designs. Residential travel, commercial travel and building energy use are included and the framework integrates household behavior change assessment to explore the environmental and economic outcomes of policies that affect infrastructure. The results show that upfront environmental and economic investments are needed (through more energy-intense building materials for high-density structures) to produce long run benefits in reduced building energy use and automobile travel. The annualized life-cycle benefits of transit-oriented developments in Phoenix can range from 1.7-230 Gg CO2e depending on the aggressiveness of residential density. Midpoint impact stressors for respiratory effects and photochemical smog formation are also assessed and can be reduced by 1.2-170 Mg PM10e and 41-5,200 Mg O3e annually. These benefits will come at an additional construction cost of up to $410 million resulting in a cost of avoided CO2e at $16-29 and household cost savings.
There is significant interest in reducing urban growth impacts yet little information exists to comprehensively estimate the energy and air quality tradeoffs. An integrated transportation and land-use life-cycle assessment framework is developed to quantify the long-term impacts from residential infill, using the Phoenix light rail system as a case study. The results show that (1) significant reductions in life-cycle energy use, greenhouse gas emissions, respiratory, and smog impacts are possible; (2) building construction, vehicle manufacturing, and energy feedstock effects are significant; and (3) marginal benefits from reduced automobile use and potential household behavior changes exceed marginal costs from new rail service.
Public transportation systems are often part of strategies to reduce urban environmental impacts from passenger transportation, yet comprehensive energy and environmental life-cycle measures, including upfront infrastructure effects and indirect and supply chain processes, are rarely considered. Using the new bus rapid transit and light rail lines in Los Angeles, near-term and long-term life-cycle impact assessments are developed, including consideration of reduced automobile travel. Energy consumption and emissions of greenhouse gases and criteria pollutants are assessed, as well the potential for smog and respiratory impacts. Results show that life-cycle infrastructure, vehicle, and energy production components significantly increase the footprint of each mode (by 48–100% for energy and greenhouse gases, and up to 6200% for environmental impacts), and emerging technologies and renewable electricity standards will significantly reduce impacts. Life-cycle results are identified as either local (in Los Angeles) or remote, and show how the decision to build and operate a transit system in a city produces environmental impacts far outside of geopolitical boundaries. Ensuring shifts of between 20–30% of transit riders from automobiles will result in passenger transportation greenhouse gas reductions for the city, and the larger the shift, the quicker the payback, which should be considered for time-specific environmental goals.
This paper examines the potential for incorporation of life-cycle assessment (LCA) into transportation planning and policy, by drawing upon analysis and precedent-setting policy structures from California. The paper first summarizes a case study of a transportation-system LCA for Los Angeles County, and briefly describes the existing structure of transportation policy, emissions regulation, and the existing partial precedents for the incorporation of LCA and decision criteria into transportation policy and planning. Using standard criteria for good policy, the paper then identifies and describes six possible policy mechanisms for incorporating LCA into the transportation planning process. These include legislative requirements for project planning, a preferential finance program, a planning standard for Regional Transportation Plans, an environmental impact assessment criterion, a criterion for selection of Transportation Control Measures under the federal Clean Air Act, and a cap-and-trade system for transportation-related life-cycle emissions. The advantages and disadvantages of each approach are identified, with an ultimate recommendation to refine and pursue a blended approach focusing on the regional planning scale.
The current institutional process for project-level environmental review, the government-required Environmental Impact Statement (EIS), requires assessment of the proposed project, the no-build alternative, and alternatives to the proposed project. Despite growing academic research to compare the environmental impacts of air and high-speed rail (HSR) infrastructure, there are few instances of multimodal alternatives analysis in airport and HSR EIS documents. In this paper, examples of EISs for air and HSR capacity-enhancement projects are chronicled to identify key challenges to completing modal alternative analysis in the EIS: the spatial heterogeneity of the physical infrastructure for air and HSR, the framing of EIS purpose and need statements, and the complicated interpretations of environmental impact significance thresholds. The paper concludes by proposing strategies to incentivize modal alternative assessments and highlight methods that are needed to perform high-quality comparative analysis to inform decision makers, whether in the context of the EIS or in upstream planning processes.
Urban sustainability assessment should integrate urban metabolism and life-cycle impact assessment to develop an integrated multi-scale framework for evaluating resource depletion and damages to human health and environmental quality. A streamlined framework can be developed by employing emerging neighborhood-scale data, improving resource depletion and damage to human health and environmental quality characterizations, including socio-demographic characteristics, and integrating methods for making decisions with uncertainty. Foundational elements and an analytical path exist to integrate urban metabolism and life-cycle impact assessment in a streamlined manner. Urban sustainability practitioners must eventually develop new methods for integrating social, institutional, and cultural forces instead of focusing on physical systems.
Government subsidies that favor all-electric travel might seem to be the obvious strategy to reduce vehicle air emissions and fossil fuel use, but short range plug-in hybrids (with long range gasoline backup) offer more benefits at lower cost.
Sustainable mobility policy for long-distance transportation services should consider emerging automobiles and aircraft as well as infrastructure and supply chain life-cycle effects in the assessment of new high-speed rail systems. Using the California corridor, future automobiles, high-speed rail and aircraft long-distance travel are evaluated, considering emerging fuel-efficient vehicles, new train designs and the possibility that the region will meet renewable electricity goals. An attributional per passenger-kilometer-traveled life-cycle inventory is first developed including vehicle, infrastructure and energy production components. A consequential life-cycle impact assessment is then established to evaluate existing infrastructure expansion against the construction of a new high-speed rail system. The results show that when using the life-cycle assessment framework, greenhouse gas footprints increase significantly and human health and environmental damage potentials may be dominated by indirect and supply chain components. The environmental payback is most sensitive to the number of automobile trips shifted to high-speed rail, and for greenhouse gases is likely to occur in 20–30 years. A high-speed rail system that is deployed with state-of-the-art trains, electricity that has met renewable goals, and in a configuration that endorses high ridership will provide significant environmental benefits over existing modes. Opportunities exist for reducing the long-distance transportation footprint by incentivizing large automobile trip shifts, meeting clean electricity goals and reducing material production effects.
Carbon dioxide capture and storage (CCS) is increasingly seen as a way for society to enjoy the benefits of fossil fuel energy sources while avoiding the climate disruption associated with fossil CO2 emissions. A decision to deploy CCS technology at scale should be based on robust information on its overall costs and benefits. Life-cycle assessment (LCA) is a framework for holistic assessment of the energy and environmental footprint of a system, and can provide crucial information to policy-makers, scientists, and engineers as they develop and deploy CCS systems. We identify seven key issues that should be considered to ensure that conclusions and recommendations from CCS LCA are robust: energy penalty, functional units, scale-up challenges, non-climate environmental impacts, uncertainty management, policy-making needs, and market effects. Several recent life-cycle studies have focused on detailed assessments of individual CCS technologies and applications. While such studies provide important data and information on technology performance, such case-specific data are inadequate to fully inform the decision making process. LCA should aim to describe the system-wide environmental implications of CCS deployment at scale, rather than a narrow analysis of technological performance of individual power plants.
Automobile air emissions are a well-recognized problem and have been subject to considerable regulation. An increasing concern for greenhouse gas emissions draws additional considerations to the externalities of personal vehicle travel. This paper provides estimates of the costs for automobile air emissions for 86 U.S. metropolitan areas based on county-specific external air emission morbidity, mortality, and environmental costs. Total air emission costs in the urban areas are estimated to be 145 million/day, with Los Angeles, California, and New York City (each23 million per day) having the highest totals. These external costs average 0.64 per day per person and0.03 per vehicle mile traveled. Total air emission cost solely due to traffic congestion for the same 86 U.S. metropolitan areas was also estimated to be $24 million per day. These estimates are compared with others in the literature and are found to be generally consistent. These external automobile air emission costs are important for social benefit and cost assessment of transportation measures to reduce vehicle use. However, this study does not include any abatement costs associated with automobile emission controls or government investments to reduce emissions such as traffic signal setting.
We assess the economic value of life-cycle air emissions and oil consumption from conventional vehicles, hybrid-electric vehicles (HEVs), plug-in hybrid-electric vehicles (PHEVs), and battery electric vehicles in the US. We find that plug-in vehicles may reduce or increase externality costs relative to grid-independent HEVs, depending largely on greenhouse gas and SO2 emissions produced during vehicle charging and battery manufacturing. However, even if future marginal damages from emissions of battery and electricity production drop dramatically, the damage reduction potential of plug-in vehicles remains small compared to ownership cost. As such, to offer a socially efficient approach to emissions and oil consumption reduction, lifetime cost of plug-in vehicles must be competitive with HEVs. Current subsidies intended to encourage sales of plug-in vehicles with large capacity battery packs exceed our externality estimates considerably, and taxes that optimally correct for externality damages would not close the gap in ownership cost. In contrast, HEVs and PHEVs with small battery packs reduce externality damages at low (or no) additional cost over their lifetime. Although large battery packs allow vehicles to travel longer distances using electricity instead of gasoline, large packs are more expensive, heavier, and more emissions intensive to produce, with lower utilization factors, greater charging infrastructure requirements, and life-cycle implications that are more sensitive to uncertain, time-sensitive, and location-specific factors. To reduce air emission and oil dependency impacts from passenger vehicles, strategies to promote adoption of HEVs and PHEVs with small battery packs offer more social benefits per dollar spent.
The US parking infrastructure is vast and little is known about its scale and environmental impacts. The few parking space inventories that exist are typically regionalized and no known environmental assessment has been performed to determine the energy and emissions from providing this infrastructure. A better understanding of the scale of US parking is necessary to properly value the total costs of automobile travel. Energy and emissions from constructing and maintaining the parking infrastructure should be considered when assessing the total human health and environmental impacts of vehicle travel. We develop five parking space inventory scenarios and from these estimate the range of infrastructure provided in the US to be between 105 million and 2 billion spaces. Using these estimates, a life-cycle environmental inventory is performed to capture the energy consumption and emissions of greenhouse gases, CO, SO2, NOX, VOC (volatile organic compounds), and PM10 (PM: particulate matter) from raw material extraction, transport, asphalt and concrete production, and placement (including direct, indirect, and supply chain processes) of space construction and maintenance. The environmental assessment is then evaluated within the life-cycle performance of sedans, SUVs (sports utility vehicles), and pickups. Depending on the scenario and vehicle type, the inclusion of parking within the overall life-cycle inventory increases energy consumption from 3.1 to 4.8 MJ by 0.1–0.3 MJ and greenhouse gas emissions from 230 to 380 g CO2e by 6–23 g CO2e per passenger kilometer traveled. Life-cycle automobile SO2 and PM10 emissions show some of the largest increases, by as much as 24% and 89% from the baseline inventory. The environmental consequences of providing the parking spaces are discussed as well as the uncertainty in allocating paved area between parking and roadways.
The state of California is expected to have significant population growth in the next half-century resulting in additional passenger transportation demand. Planning for a high-speed rail system connecting San Diego, Los Angeles, San Francisco, and Sacramento as well as many population centers between is now underway. The considerable investment in California high-speed rail has been debated for some time and now includes the energy and environmental tradeoffs. The per-trip energy consumption, greenhouse gas emissions, and other emissions are often compared against the alternatives (automobiles, heavy rail, and aircraft), but typically only considering vehicle operation. An environmental life-cycle assessment of the four modes was created to compare both direct effects of vehicle operation and indirect effects from vehicle, infrastructure, and fuel components. Energy consumption, greenhouse gas emissions, and SO2, CO, NOX, VOC, and PM10 emissions were evaluated. The energy and emission intensities of each mode were normalized per passenger kilometer traveled by using high and low occupancies to illustrate the range in modal environmental performance at potential ridership levels. While high-speed rail has the potential to be the lowest energy consumer and greenhouse gas emitter, appropriate planning and continued investment would be needed to ensure sustained high occupancy. The time to environmental payback is discussed highlighting the ridership conditions where high-speed rail will or will not produce fewer environmental burdens than existing modes. Furthermore, environmental tradeoffs may occur. High-speed rail may lower energy consumption and greenhouse gas emissions per trip but can create more SO2 emissions (given the current electricity mix) leading to environmental acidification and human health issues. The significance of life-cycle inventorying is discussed as well as the potential of increasing occupancy on mass transit modes.
A comparative life-cycle energy and emissions (greenhouse gas, CO, NOX, SO2, PM10, and VOCs) inventory is created for three U.S. metropolitan regions (San Francisco, Chicago, and New York City). The inventory captures both vehicle operation (direct fuel or electricity consumption) and non-operation components (e.g., vehicle manufacturing, roadway maintenance, infrastructure operation, and material production among others). While urban transportation inventories have been continually improved, little information exists identifying the particular characteristics of metropolitan passenger transportation and why one region may differ from the next. Using travel surveys and recently developed transportation life-cycle inventories, metropolitan inventories are constructed and compared. Automobiles dominate total regional performance accounting for 86–96% of energy consumption and emissions. Comparing system-wide averages, New York City shows the lowest end-use energy and greenhouse gas footprint compared to San Francisco and Chicago and is influenced by the larger share of transit ridership. While automobile fuel combustion is a large component of emissions, diesel rail, electric rail, and ferry service can also have strong contributions. Additionally, the inclusion of life-cycle processes necessary for any transportation mode results in significant increases (as large as 20 times that of vehicle operation) for the region. In particular, emissions of CO2 from cement production used in concrete throughout infrastructure, SO2 from electricity generation in non-operational components (vehicle manufacturing, electricity for infrastructure materials, and fuel refining), PM10 in fugitive dust releases in roadway construction, and VOCs from asphalt result in significant additional inventory. Private and public transportation are disaggregated as well as off-peak and peak travel times. Furthermore, emissions are joined with healthcare and greenhouse gas monetized externalities to evaluate the societal costs of passenger transportation in each region. Results are validated against existing studies. The dominating contribution of automobile end-use energy consumption and emissions is discussed and strategies for improving regional performance given private travel's disproportionate share are identified.
To appropriately mitigate environmental impacts from transportation, it is necessary for decision makers to consider the life-cycle energy use and emissions. Most current decision-making relies on analysis at the tailpipe, ignoring vehicle production, infrastructure provision, and fuel production required for support. We present results of a comprehensive life-cycle energy, greenhouse gas emissions, and selected criteria air pollutant emissions inventory for automobiles, buses, trains, and airplanes in the US, including vehicles, infrastructure, fuel production, and supply chains. We find that total life-cycle energy inputs and greenhouse gas emissions contribute an additional 63% for onroad, 155% for rail, and 31% for air systems over vehicle tailpipe operation. Inventorying criteria air pollutants shows that vehicle non-operational components often dominate total emissions. Life-cycle criteria air pollutant emissions are between 1.1 and 800 times larger than vehicle operation. Ranges in passenger occupancy can easily change the relative performance of modes.
As cellulosic ethanol technologies advance, states could use the organic content of municipal solid waste as a transportation fuel feedstock and simultaneously reduce externalities associated with waste disposal. We examine the major processes required to support a lignocellulosic (employing enzymatic hydrolysis) municipal solid waste-to-ethanol infrastructure computing cost, energy, and greenhouse gas effects for California. The infrastructure is compared against the Business As Usual case where the state continues to import most of its ethanol needs from the Midwest. Assuming between 60% and 90% practical yields for ethanol production, California could produce between 1.0 and 1.5 billion gallons per year of ethanol from 55% of the 40 million metric tonnes of waste currently sent to landfills annually. The classification of organic wastes and ethanol plant operation represent almost the entire system cost (between $3.5 and $4.5 billion annually) while distribution has negligible cost effects and savings from avoided landfilling is small. Fossil energy consumption from Business As Usual decreases between 82 and 130 PJ largely due to foregone gasoline consumption. The net greenhouse gas impacts are ultimately dependent on how well landfills control their emissions of decomposing organics. Based on the current landfill mix in the state, the cellulosic infrastructure would experience a slight gain in greenhouse gas emissions. However, net emissions can rise if organics diversion releases carbon that would otherwise be flared and sequestered. Emissions would be avoided if landfills are not capable of effectively controlling emissions during periods of active waste decay. There is currently considerable uncertainty surrounding the recovery efficiency of landfill emissions controls. In either case, burying lignin appears to be better than burning lignin because of its decay properties, energy and carbon content. We estimate the breakeven price for lignocellulosic ethanol between $2.90 and $3.47/gal (μ = $3.13/gal).
Curbside recycling programs can be more cost-effective than landfilling and lead to environmental benefits from the recovery of materials. Significant reductions in energy and emissions are derived from the decrease of energy-intensive production with virgin materials. In many cities, competing priorities can lead to limited consideration given to system optimal collection and processing strategies that can drive down costs and increase revenue while simultaneously reducing system energy consumption and greenhouse gas (GHG) emissions. We evaluate three alterations to a hypothetical California city’s recycling network to discern the conditions under which the changes constitute system improvements to cost, energy, and emissions. The system initially operates with a collection zoning scheme that does not mitigate the impact of seasonal variations in consumer tonnage. In addition, two collection organizations operate redundantly, collecting recyclables from different customer types on the same street network. Finally, the system is dual stream, meaning recyclables are separated at the curbside. In some scenarios, this practice can limit the consumer participation rate leading to lower collection quantities. First, we evaluate a “business as usual” (BAU) scenario and find that the system operates at a $1.7 M/yr loss but still avoids a net 18.7 GJ and 1700 kg of greenhouse gas equivalent (GGE) per ton of material recycled. Second, we apply an alternative zoning scheme for collection that creates a uniform daily pickup demand throughout the year reducing costs by $0.2 M/yr, energy by 30 MJ/ton, and GHG emissions by 2 kg GGE/ton. Next, the two collection organizations are consolidated into a single entity further reducing vehicle fleet size and weekly vehicle miles traveled resulting in savings from BAU of $0.3 M/yr, 100 MJ/ton, and 8 kg GGE/ton. Lastly, we evaluate a switch to a single-stream system (where recyclables are commingled). We show that single-stream recycling can increase the total amount of material collected to a degree that lowers overall net cost ($0.2 M/yr) and leads to further reductions in energy use (210 MJ/ton) and emissions (16 kg GGE/ton). However, there can be circumstances in which maintaining a consolidated dual stream system is preferred over single stream. A sensitivity analysis is also performed and a discussion is presented addressing the applicability of this city network to others.
Construction mismanagement results in multiple problems that can cascade throughout the work force chain, affecting the schedule and leading to damages to multiple parties. Although the problem may start with a single subcontractor, it can result in all contractors feeling some impact to their work. In this paper, a case study is presented of a project with seven different mismanagement scenarios. A description of each scenario is provided as well as a quantification of the damages that result from the problem. A construction claims section is also included that addresses many of the issues that could result from a claim for each of the seven scenarios. A discussion is presented outlining possible preventative steps to minimize the damages from the problems presented.
The growth of cities is largely associated with the dominant technologies of the time and over the past two centuries these technologies have relied on fossil-based energy sources. From automobile travel to long-distance water conveyance to air conditioning, urban infrastructure in newer cities and developing cities is built upon the notion that low cost energy resources and natural resources will continue. As we become increasingly aware of the constraints on these resources, a pressing need emerges for reimagining how cities should grow. Gone are the days when engineers and planners could deploy civil systems without considering the sustainability impacts of their choices and how these systems result in impacts to both the people that use them and the natural environment. As such, new frameworks are needed for understanding the role of engineered systems in affecting emergent behaviors, and how these behaviors produce impacts. Using Southwestern United States cities as case studies, we explore the relationship between infrastructure design and the sustainability of emergent behaviors in cities, and how the redesign of infrastructure in neighborhoods can reduce environmental impacts.
Urban sustainability decision makers should incorporate time-based impacts of greenhouse gas emissions with life cycle assessment to improve climate change mitigation strategies. As cities develop strategies that move development closer to transit systems and encourage households to live in lower energy configurations, new methods are needed for understanding how upfront emissions of greenhouse gases produce long run radiative forcing impacts. Using an existing assessment of the development potential around Phoenix’s new light rail system, a framework is developed for deploying higher density, lower energy use, and more transit-friendly households near light rail given financing constraints. The case study compares development around transit stations in Phoenix against continued outward growth of single family homes. Using this case study, the significance of greenhouse gas (GHG) radiative forcing discounting is assessed. The radiative forcing benefits of different levels of financing aggressiveness are shown. A comparison of payback on upfront construction impacts for long run benefits is developed between the GHG accounting approach and the radiative forcing approach, the latter of which accounts for time-based GHG impacts. The results show that the radiative forcing approach puts more weight on upfront construction impacts and pushes the payback on initial investments out further than when GHG accounting is used. It is possible to reduce this payback time by providing a larger upfront financing resource. Ultimately, policy and decision makers should use radiative forcing measures over GHG measures because it will provide a measure that discounts GHG emissions at different times to a normalized unit.
This paper examines the potential for incorporation of life cycle assessment (LCA) into transportation planning and policy, with a particular focus on California. The paper first summarizes a case study of transportation-system LCA in Los Angeles County, and briefly describes the existing structure of transportation policy, emissions regulation, and the existing partial precedents for the incorporation of life cycle assessment and decision criteria into transportation policy and planning. Using standard criteria for good policy, the paper then identifies and describes six possible policy mechanisms for incorporating life cycle assessment into the transportation planning process. These include legislative requirements for project planning, a preferential finance program, a planning standard for Regional Transportation Plans, an environmental impact assessment criterion for use under the California Environmental Quality Act (CEQA), a criterion for selection of Transportation Control Measures under regional Air Quality Management Plans, and a cap-and-trade system for transportation-related life cycle emissions modeled after California’s Low Carbon Fuel Standard. The advantages and disadvantages of each approach are identified, with an ultimate recommendation to refine and pursue a blended approach focusing on the regional planning scale.
The current institutional process for project-level environmental review, the government-required Environmental Impact Statement (EIS), requires assessment of the proposed project, the no-build alternative, and alternatives to the proposed project. Despite growing academic research to compare the environmental impacts of air and high-speed rail (HSR) infrastructure, there are few instances of multimodal alternatives analysis in airport and HSR EIS documents. In this paper, examples of EISs for air and HSR capacity-enhancement projects are chronicled to identify key challenges to completing modal alternative analysis in the EIS: the spatial heterogeneity of the physical infrastructure for air and HSR, the framing of EIS purpose and need statements, and the complicated interpretations of environmental impact significance thresholds. The paper concludes by proposing strategies to incentivize modal alternative assessments and highlight methods that are needed to perform high-quality comparative analysis to inform decision makers, whether in the context of the EIS or in upstream planning processes.
Life Cycle Assessment (LCA) should be used to assist carbon capture and sequestration (CCS) planners to reduce greenhouse gas (GHG) emissions and avoid unintended environmental trade-offs. LCA is an analytical framework for determining environmental impacts resulting from processes, products, and services. All life cycle stages are evaluated including raw material sourcing, processing, operation, maintenance, and component end-of-life, as well as intermediate stages such as transportation. In recent years a growing number of LCA studies have analyzed CCS systems. We reviewed 50+ LCA studies, and selected 11 studies that compared the environmental performance of 23 electric power plants with and without CCS. Here we summarize and interpret the findings of these studies. Regarding overall climate mitigation effectiveness of CCS, we distinguish between the capture percentage of carbon in the fuels, the net carbon dioxide (CO2) emission reduction, and the net GHG emission reduction. We also identify trade-offs between the climate benefits and the potential increased non-climate impacts of CCS. Emissions of non-CO2 flue gases such as NOx may increase due to the greater throughput of fuel, and toxicity issues may arise due to the use of monoethanolamine (MEA) capture solvent, resulting in ecological and human health impacts. We discuss areas where improvements in LCA data or methods are needed. The decision to implement CCS should be based on knowledge of the overall environmental impacts of the technologies, not just their carbon capture effectiveness. LCA will be an important tool in providing that knowledge.
An automated system for logging and retrieving digital photographs based on location and photograph direction was developed. New pictures were automatically tagged with camera location, direction and time stamps, and then stored in a relational database. The database can be accessed from Computer-Aided Design and Geographic Information Systems and photos of individual components or objects are identified and displayed on request based on a geometric search algorithm.
Forecasting and Life Cycle Assessment for High-speed Rail Energy and Environmental Assessment chapter background:
Environmental assessments of high-speed rail (HSR) systems consider competing long-distance transportation modes, typically, automobiles and aircraft, to understand human health, environmental, resource depletion and climate change impacts. The focus of each assessment is driven by the knowledge goals of the decision maker conducting the study. Government agencies developing environmental impact statements tend to focus on local and regional impacts whereas academic studies (which often assess multiple decision maker influences within a large system) have often focused on energy and greenhouse gas assessment. Regardless, there is a broad suite of impacts of concern for long-distance transportation services and environmental assessments should consider multiple impacts to understand how strategies can produce co-benefits or implement mitigation strategies to reduce the likelihood of unintended tradeoffs..
To date, many environmental comparisons of air and HSR systems have sought to determine the per passenger kilometer/mile, vehicle kilometer/mile, or trip differences. Attributional approaches construct the system boundary to assess long-run average effects, where environmental impacts are allocated to the passenger or vehicle at some point in time. While attributional approaches are valuable for identifying the technological characteristics of the system, the results do not directly answer how environmental effects in a region change because of a decision that affects air or HSR systems. Consequential approaches do just this. Consequential assessment calls for a system boundary that includes processes that change (marginal effects) based on a policy or a decision..
Whether attributional or consequential framing is more appropriate, there is a growing body of research that seeks to improve the environmental assessment of HSR by i) more rigorously assessing the mode shifting behavior and future forecasting, and ii) applying the life cycle assessment (LCA) framework for comprehensive assessment of the geospatial changes in complex systems and their human health, environmental, resource depletion, and climate change impacts.
Environmental Life Cycle Assessment is an introductory college level textbook on the science of Life Cycle Assessment. It provides materials for a full year of study. Over thirty LCA experts were brought together by the American Center for Life Cycle Assessment, with full redundant editing to provide a consistent and comprehensive coverage of this broad field of study. Exercises are provide for each topic, covering everything from the nuts and bolts of the science to issues such as ethics and communication. Students using this textbook need only practical experience (as can be provided in lab courses) to be able to sit the exam for Life Cycle Assessment Certified Professionals.
Despite the many benefits of energy, most of which are reflected in energy market prices, the production, distribution, and use of energy causes negative effects. Many of these negative effects are not reflected in energy market prices. When market failures like this occur, there may be a case for government interventions in the form of regulations, taxes, fees, tradable permits, or other instruments that will motivate recognition of these external or hidden costs.
Recent climatic trends show more flooding and extreme heat events and in the future transportation infrastructure may be susceptible to more frequent and intense environmental perturbations. Our transportation systems have largely been designed to withstand historical weather events, for example, floods that occur at an intensity that is experience once every 100 years, and there is evidence that these events are expected become more frequent. There are increasing efforts to better understand the impacts of climate change on transportation infrastructure. An abundance of new research is emerging to study various aspects of climate change on transportation systems. Much of this research is focused on roadway networks and reliable automobile travel. We explore how flooding and extreme heat might impact passenger rail systems in the Northeast and Southwest U.S..
As the number of heat waves are expected to increase significantly into the future in the U.S. Southwest, new insight is needed into how urban infrastructure can be repositioned to protect people. In the Phoenix metro area infrastructure have largely been deployed over the past half century, during a time when climate change was not a concern. Now, as the county struggles to protect people from heat, there is a need to reassess how existing and new infrastructure can be positioned to reduce health impacts while improving sustainability. Using a neighborhood in Mesa, Arizona as a case study, we assess how changes to transportation infrastructure, building infrastructure, and landscaping can reduce heat exposure. A number of strategies are considered including the optimal deployment of heat refuges, deploying less convective surface materials, and deploying more thermally preferable building materials. The suite of strategies could be considered by cities throughout the Phoenix metro area.
Already the leading cause of weather-related deaths in the United States, extreme heat events (EHEs) are expected to occur with greater frequency, duration and intensity over the next century. However, not all populations are affected equally. Risk factors for heat mortality—including age, race, income level, and infrastructure characteristics—often vary by geospatial location. While traditional epidemiological studies sometimes account for social risk factors, they rarely account for intra-urban variability in meteorological characteristics, or for the interaction between social and meteorological risks. This study aims to develop estimates of EHEs at an intra-urban scale for two major metropolitan areas in the Southwest: Maricopa County (Arizona) and Los Angeles County (California). EHEs are identified at a 1/8-degree (12 km) spatial resolution using an algorithm that detects prolonged periods of abnormally high temperatures. Downscaled temperature projections from three general circulation models (GCMs) are analyzed under three relative concentration pathway (RCP) scenarios. Over the next century, EHEs are found to increase by 340-1800% in Maricopa County, and by 150-840% in Los Angeles County. Frequency of future EHEs is primarily driven by greenhouse gas concentrations, with the greatest number of EHEs occurring under the RCP 8.5 scenario. Intra-urban variation in EHEs is also found to be significant. Within Maricopa County, “high risk” regions exhibit 4.5 times the number of EHE days compared to “low risk” regions; within Los Angeles County, this ratio is 15 to 1.
Climatic changes have the potential to impact electricity generation in the U.S. Southwest and methods are needed for estimating how cities will be impacted. This study builds an electricity vulnerability risk index for two Southwest cities (Phoenix and Los Angeles) based on climate-related changes in electricity generation capacity. Planning reserve margins (PRM) are used to estimate the potential for blackouts and brownouts under future climate scenarios. Reductions in PRM occur in both cities in 2016 with the most significant reductions occurring in regions relying more heavily on hydropower.
In recent years, concerns have grown over the risks posed by climate change on the U.S. electricity grid. The availability of water resources is integral to the production of electric power, and droughts are expected to become more frequent, severe, and longer-lasting over the course of the twenty-first century. The American Southwest, in particular, is expected to experience large deficits in streamflow. Studies on the Colorado River anticipate streamflow declines of 20-45% by 2050. Other climactic shifts—such as higher water and air temperatures—may also adversely affect power generation. As extreme weather becomes more common, better methods are needed to assess the impact of climate change on power generation. This study uses a physically-based modeling system to assess the vulnerability of power infrastructure in the Southwestern United States at a policy-relevant scale.
Thermoelectric power—which satisfies a majority of U.S. electricity demand—is vulnerable to drought. Thermoelectric power represents the backbone of the U.S. power sector, accounting for roughly 91% of generation. Thermoelectric power also accounts for roughly 39% of all water withdrawals in the U.S.—roughly equivalent to the amount of water used for agriculture. Water use in power plants is primarily dictated by the needs of the cooling system. During the power generation process, thermoelectric power plants build up waste heat, which must be discharged in order for the generation process to continue. Traditionally, water is used for this purpose, because it is safe, plentiful, and can absorb a large amount of heat. However, when water availability is constrained, power generation may also be adversely affected. Thermoelectric power plants are particularly susceptible to changes in streamflow and water temperature. These vulnerabilities are exacerbated by environmental regulations, which govern both the amount of water withdrawn, and the temperatures of the water discharged. In 2003, extreme drought and heat impaired the generating capacity of more than 30 European nuclear power plants, which were unable to comply with environmental regulations governing discharge temperatures. Similarly, many large base-load thermoelectric facilities in the Southeastern United States were threatened by a prolonged drought in 2007 and 2008. During this period, the Tennessee Valley Authority (TVA) reduced generation at several facilities, and one major facility was shut down entirely. To meet demand, the TVA was forced to purchase electricity from the grid, causing electricity prices to rise.
Although thermoelectric power plants currently produce most of the electric power consumed in the United States, other sources of power are also vulnerable to changes in climate. Renewables are largely dependent on natural resources like rain, wind, and sunlight. As the quantity and distribution of these resources begins to change, renewable generation is also likely to be affected. Hydroelectric dams represent the largest source of renewable energy currently in use throughout the United States. Under drought conditions, when streamflow attenuates and reservoir levels drop, hydroelectric plants are unable to operate at normal capacity. In 2001, severe drought in California and the Pacific Northwest restricted hydroelectric power generation, causing a steep increase in electricity prices. Although blackouts and brownouts were largely avoided, the Northwest Power and Conservation Council estimated a regional economic impact of roughly $2.5 to $6 billion. In addition to hydroelectric power, it has also been theorized that solar energy resources may also be susceptible to predicted increases in surface temperature and atmospheric albedo. One study predicts that solar facilities in the Southwestern U.S. may suffer losses of 2-5%.
The aim of this study is to estimate the extent to which climate change may impact power generation in the Southwestern United States. This analysis will focus on the Western Interconnection, which comprises the states of Washington, Oregon, California, Idaho, Nevada, Utah, Arizona, Colorado, Wyoming, Montana, South Dakota, New Mexico and Texas. First, climactic and hydrologic parameters relevant to power generation are identified for five types of generation technologies. A series of functional relationships are developed such that impacts to power generation can be estimated directly from changes in certain meteorological and hydrological parameters. Next, climate forcings from the CMIP3 multi-model ensemble are used as inputs to a physically-based modeling system (consisting of a hydrological model, an offline routing model, and a one-dimensional stream temperature model). The modeling system is used to estimate changes in climactic and hydrologic parameters relevant to electricity generation for various generation technologies. Climactic and hydrologic parameters are then combined with the functional relationships developed in the first step to estimate impacts to power generation over the twenty-first century.
As California establishes its greenhouse gas emissions cap-and-trade program and considers options for using the new revenues produced under the program, the public and decision-makers have access to tenuous information on the relative cost-effectiveness of passenger transportation investment options. In a step toward closing this knowledge gap, we compare the cost-effectiveness of greenhouse gas reductions forecast to come to California High-Speed Rail with those estimated from recent urban transportation projects (specifically light rail, bus rapid transit, and bicycling) in California. The goal of the study is to link life-cycle greenhouse gas emissions estimates with full cost accounting to better understand the benefits of cap-and-trade investments.
The US-Canadian electricity grid is a network of providers and users that operate almost completely independently of one another. In August of 2003, First Energy’s (FE) Harding-Chamberlain transmission line near Akron, Ohio went offline starting a series of cascading failures that eventually led to 8 US states and 1 Canadian province totaling nearly 50 million people without power. The failure of transmission lines are common occurrences relating to the inability to exactly predict the electricity demand at any time (as will be discussed later in this document). The inability to properly monitor and react across multiple organizations to the downed line was the true failure that led to the blackout. This outage not only left homes and businesses without power but paralyzed critical public services such as transportation networks and hospitals. The estimated cost of the outage is between 4 and 6 billion US dollars.
Building energy assessment often focuses on the use of electricity and natural gas during the use phase of a structure while ignoring the energy investments necessary to construct the facility. This research develops a methodology for quantifying the “embedded” energy and greenhouse gases (GHG) in the building infrastructure of an entire metropolitan region. “Embedded” energy and GHGs refer to the energy necessary to manufacture materials and construct the infrastructure. Using these methods, a case study is developed for Los Angeles County.
There is significant experience and research on the competition of air and high-speed rail (HSR) modes. The existing research covers areas including system structure (vehicle technology, cost, ridership, etc.) and environmental effects. The objective of the Environmental Assessment of Air and High-Speed Rail Corridors synthesis is to bring together research and other findings related to air and HSR environmental assessments and to understand where additional research can improve our ability to assess the environmental outcomes of these two systems. A literature review is the primary tool for collecting data for this synthesis of current practice.
Through the synthesis of the literature, major gaps in knowledge were found:
i) Methodological frameworks and tools that assess future operating characteristics of long-distance transportation service have not been fully developed. Such frameworks and tools must address the two main components of the relationship between air and HSR: as competitors and as complementary modes.
ii) A framework and methodology are needed to analyze the impact to airline operations, and thus airport infrastructure use, of development of HSR. The same goes for the “no build” alternative: estimating the future of aviation flows in the absence of HSR infrastructure is necessary.
iii) By performing consequential assessments instead of attributional assessments, organizations will have information about the outcome of decisions that affect air and HSR systems. The consequential assessment will require an understanding of how up-front investments will lead to regional operating effects. Although NEPA in many ways requires a consequential assessment, the academic literature has for the most part avoided these quantifications, likely because of the complexities of accurate estimates.
In conclusion, environmental assessments of air and HSR systems have produced valuable knowledge but the creation of novel data analysis and methods will improve our understanding of future networks that house both modes. The large body of literature reviewed does not lead to a single cohesive conclusion relating air and HSR comparative environmental analysis. By establishing regional planning processes, drawing on previously established methods, and developing new tools and information for better understanding future processes, more comprehensive approaches can be developed to better understand the co-benefits of intelligent air and HSR planning.
The decision to construct and operate a public transit system is often touted as an energy and environmental improvement from automobile travel. Few studies exist that comprehensively compare the environmental costs and benefits of new public transit. An environmental life cycle assessment is developed for the Los Angeles Metro Orange bus rapid transit line, Los Angeles Metro Gold light rail transit line, and a competing automobile trip. The life cycle assessment includes vehicle, infrastructure, and energy production components and evaluates energy inputs, conventional air pollutants, and greenhouse gas emissions. For energy inputs and greenhouse gas emissions the Orange and Gold lines show significant benefits per passenger mile traveled over the automobile, and life cycle effects can significantly increase all mode’s footprints. Conventional air pollutants can be dominated by life cycle effects (with vehicle operation accounting in some cases for only a small fraction of total effects), particularly vehicle manufacturing and maintenance, infrastructure construction and operation, and energy production. Results are expressed total and marginal travel, and sensitivity to occupancy is determined in a breakeven analysis. The breakeven analysis reports the occupancy range where the Orange and Gold lines outperform an equivalent automobile trip. The policy implications of including life cycle effects and a broad suite of environmental indicators are discussed.
Those charged with making decisions regarding transportation systems have, in recent years, become more interested in the indirect impacts of these systems. This interest is in part a response to advancements in vehicle technology and evolving policy goals.
The State of California seeks to reduce emissions and conserve energy resources in all sectors of its economy and has adopted several policies that address transportation energy use and emissions. All of these policies, such as The Sustainable Communities Planning Act, consider vehicle tailpipe emissions. One policy, California’s Low Carbon Fuel Standard, also considers the effects of greenhouse gas emissions from the production and distribution of transportation fuels, even when these emissions are out of state.
The recent availability of mass-market electric vehicles also has decision-makers contemplating the indirect effects of transportation systems. Although the tailpipe emissions from an internal combustion engine vehicle are more obvious than the indirect power plant emissions generated to propel an electric vehicle, both sets of emissions affect climate change.
Life-Cycle Assessment (LCA) provides decision-makers with information needed to evaluate the direct and indirect impacts of transportation systems. This report will guide the reader through the process of identifying sources, inventorying impacts, and interpreting results specific to LCA of energy and emissions indicators for transportation projects. The authors highlight the impacts that dominate overall results and discuss how to incorporate LCA into existing transportation planning, construction, and operation processes.
This report is the consolidated work of an interdisciplinary course project in CEE494/598, CON598, and SOS598, Urban Infrastructure Anatomy and Sustainable Development. In Fall 2012, the course at Arizona State University used sustainability research frameworks and life-cycle assessment methods to evaluate the comprehensive benefits and costs when transit-oriented development is infilled along the proposed light rail transit line expansion. In each case, and in every variation of possible future scenarios, there were distinct life-cycle benefits from both developing in more dense urban structures and reducing automobile travel in the process.
Better methods are necessary to fully account for anthropogenic impacts on ecosystems and the essential services provided by ecosystems that sustain human life. Current methods for assessing sustainability, such as life cycle assessment (LCA), typically focus on easily quantifiable indicators such as air emissions with no accounting for the essential ecosystem benefits that support human or industrial processes. For this reason, more comprehensive, transparent, and robust methods are necessary for holistic understanding of urban technosphere and ecosphere systems, including their interfaces. Incorporating ecosystem service indicators into LCA is an important step in spanning this knowledge gap. For urban systems, many built environment processes have been investigated but need to be expanded with life cycle assessment for understanding ecosphere impacts. To pilot these new methods, a material inventory of the building infrastructure of Phoenix, Arizona can be coupled with LCA to gain perspective on the impacts assessment for built structures in Phoenix. This inventory will identify the origins of materials stocks, and the solid and air emissions waste associated with their raw material extraction, processing, and construction and identify key areas of future research necessary to fully account for ecosystem services in urban sustainability assessments. Based on this preliminary study, the ecosystem service impacts of metropolitan Phoenix stretch far beyond the county boundaries. A life cycle accounting of the Phoenix’s embedded building materials will inform policy and decision makers, assist with community education, and inform the urban sustainability community of consequences.
Water is a necessary component for life and can be a constraining factor to growth when quantitiesare limited. This is especially true in highly populated desert regions, which must then import substantial amounts water to support the population. Finding solutions to water limitations through either conservation or additional water acquisitions will be essential to the futures of these desert communities. This report is the culmination of a course project focused on the water use in Phoenix, Arizona. Water trends are analyzed looking at sector consumption over time, as well as through more innovative methods such as detailing embedded water associated with urban infrastructure and calculating the co-dependence of power plants and water provisioning. Primarily, this report contains the initial water data (reported from cities) as well as basic calculations and methodologies of assessing life cycle components of water consumption. Some comparisons are drawn between different cities in the metropolitan area. Additionally, damage costs were calculated for some aspects of water use to give an idea of the consequences associated with water use that must be mitigated.
The California Department of Toxic Substance Control (DTSC) established the Green Chemistry Initiative in 2007 to provide a framework for understanding and reducing the impacts of products containing toxic chemicals in the state. California’s Assembly Bill 1879 gives the DTSC authority to regulate chemicals of concern in consumer products. However, changing product design or switching out problem chemicals may have environmental and human health implications. Alternative assessments should employ a life-cycle perspective when evaluating products, processes, and decisions that influence the use of chemicals in products to avoid regretful substitutions or unintended consequences.
Life cycle assessment (LCA) is the preeminent framework for understanding the cradle-to-cradle environmental impacts of products, processes, services, policies, and decisions. The LCA framework provides a structure for capturing ancillary (indirect) and supply chain effects in addition to the direct effects of immediate interest. LCAs of many different systems have shown that it is often the case that the bulk of impacts occur in ancillary and supply chain processes.
To provide a consistent LCA lens in drafting of regulations and support for green chemistry practitioners, Arpad Horvath and Mikhail Chester assisted DTSC in the review of draft regulations and preparation of supporting information. This included development of a tools matrix, preparation of a literature summary of existing guidelines, and preparation of relevant case studies. The focus of the supporting information items is to provide documentation and support to green chemistry LCA practitioners. This report consolidates project deliverables into a document for DTSC to provide guidance to LCA practitioners.
The development of life-cycle energy and emissions factors for passenger transportation modes is critical for understanding the total environmental costs of travel. Previous life-cycle studies have focused on the automobile given its dominating share of passenger travel and have included only few life-cycle components, typically related to the vehicle (i.e., manufacturing, maintenance, end-of-life) or fuel (i.e., extraction, refining, transport) (MacLean 1998, Cobas-Flores 1998, Sullivan 1998). Chester (2009) provides the first comprehensive environmental life-cycle assessment of not only vehicle and fuel components but also infrastructure components for automobiles, buses, commuter rail systems, and aircraft. Many processes were included for vehicles (manufacturing, active operation, inactive operation, maintenance, insurance), infrastructure (construction, operation, maintenance, parking, insurance), and fuels (production, distribution) in Chester (2009). The vehicles inventoried were sedans, pickups, SUVs, urban diesel buses, light rail (San Francisco’s Muni Metro and Boston’s Green Line, both electric), heavy rail (San Francisco Bay Area’s BART and Caltrain), and aircraft (small, medium, and large-sized planes are disaggregated). Given the methodological framework in Chester (2009), the question of applicability of these systems to other U.S. modes, and the data availability of other modes, is extended in this study to motorcycles, light duty diesel vehicles, school buses, electric buses, Chicago commuter rail modes, and New York City commuter rail modes.
The onroad and rail modes evaluated here are chosen primarily because of data availability. While life-cycle factors are critical in understanding the full environmental costs of passenger travel, vehicle operational “tail-pipe” factors are often the dominating contributor to particular components. For example, Chester (2009) showed that while emissions of CO, SO2, VOCs, and PM10 may be dominated by non-vehicle operation factors such as roadway construction, vehicle manufacturing, or fuel production for automobiles, around 60%-70% of energy consumption and greenhouse gas (GHG) emissions are attributed to fuel combustion. This is important because high quality fuel combustion factors for onroad modes are critical for life-cycle assessments and the EPA Mobile 6.2 emissions modeling software provides these factors for motorcycles, light duty diesel vehicles, and school buses (EPA 2003). Additionally, electric buses are included based on the San Francisco Muni system. The creation of life-cycle environmental factors for these modes will provide for improved cross-comparisons of modal choices. Questions related to the use of diesel automobiles versus conventional gasoline automobiles linger and the creation of life-cycle factors for these modes will provide additional clarification for overall environmental performance. The assessment of Chicago and New York City rail systems is performed because of the transit-rich options of the regions. Adding the Chicago and New York City rail system inventories to the San Francisco Bay Area inventories already computed will provide critical data for three transit-oriented cities that will allow for regional assessments (the preliminary regional assessment is performed in and is currently being updated based on the results in this document). The diversity of rail options in these cities is greater than most other metropolitan regions and the life-cycle inventories will illuminate the critical characteristics of the systems that makes one outperform the others. The rail systems inventoried are the Chicago Metro, Chicago Metra commuter rail, New York City’s metro, the New York/New Jersey PATH metro, Newark’s LRT, and New York City’s Metro North commuter rail.
Energy use and emission factors for passenger transportation modes typically ignore the total environmental inventory which includes vehicle non-operational components (e.g., vehicle manufacturing and maintenance), infrastructure components, and fuel production components from design through end-of-life processes. A life-cycle inventory for each mode is necessary to appropriately address and attribute the transportation sector’s energy and emissions impacts to reduction goals instead of allowing tailpipe emissions to act as indicators of total system performance.
The contributions of U.S. passenger transportation modes to national energy and emissions inventories account for roughly 20% of U.S. totals, mostly attributed to gasoline consumption. Furthermore, world consumption of primary energy amounted to 490 EJ in 2005 with the U.S. responsible for 110 EJ, or 21% of the total. This means that passenger transportation in the U.S. accounts for roughly 5% of global primary energy consumption annually. With a predominant fossil fuel energy base, the impacts of U.S. passenger transportation have strong implications for global energy consumption, U.S. energy security, and climate change. Furthermore, criteria air pollutant emissions from transportation (passenger and freight) are also significant, accounting for 78% of national CO, 58% of NOX, 36% of VOCs, 9% of PM2.5, 2.6% of PM10, and 4.5% of SO2 emissions. These emissions often occur near population centers and can cause adverse direct human health effects as well as other impacts such as ground-level ozone formation and acid deposition.
To appropriately mitigate environmental impacts from transportation, it is necessary for decision makers to consider the life-cycle energy consumption and emissions associated with each mode. A life-cycle energy, greenhouse gas, and criteria air pollutant emissions inventory is created for the passenger transportation modes of automobiles, urban buses, heavy rail transit, light rail transit, and aircraft in the U.S.. Each mode’s inventory includes an assessment of vehicles, infrastructure, and fuel components. For each component, analysis is performed for material extraction through use and maintenance in both direct and indirect (supply chain) processes.
For each mode’s life-cycle components, energy inputs and emission outputs are determined. Energy inputs include electricity and petroleum-based fuels. Emission outputs include greenhouse gases (CO2, CH4, and N2O) and criteria pollutants (CO, SO2, NOX, VOCs, and PM). The inputs and outputs are normalized by vehicle lifetime, vehicle mile traveled, and passenger mile traveled. A consistent system boundary is applied to all modal inventories which captures the entire life-cycle, except for end-of-life. For each modal life-cycle component, both direct and indirect processes are included if possible. A hybrid life-cycle assessment approach is used to estimate the components in the inventories.
We find that life-cycle energy inputs and emission outputs increase significantly compared to the vehicle operational phase. Life-cycle energy consumption is 39-56% larger than vehicle operation for autos, 38% for buses, 93-160% for rail, and 19-24% for air systems per passenger mile traveled. Life-cycle greenhouse gas emissions are 47-65% larger than vehicle operation for autos, 43% for buses, 39-150% for rail, and 24-31% for air systems per passenger mile traveled. The energy and greenhouse gas increases are primarily due to vehicle manufacturing and maintenance, infrastructure construction, and fuel production. For criteria air pollutants, life-cycle components often dominate total emissions and can be a magnitude larger than operational counterparts. Per passenger mile traveled, total SO2 emissions (between 350 and 460 mg) are 19-27 times larger than operational emissions as a result of electricity generation in vehicle manufacturing, infrastructure construction, and fuel production. NOX emissions increase 50-73% for automobiles, 24% for buses, 13-1300% for rail, and 19-24% for aircraft. Non-tailpipe VOCs are 27-40% of total automobile, 71-95% of rail, and 51-81% of air total emissions. Infrastructure and parking construction are major components of total PM10 emissions resulting in total emissions over three times larger than operational emissions for autos and even larger for many rail systems and aircraft (the major contributor being emissions from hot-mix asphalt plants and concrete production). Infrastructure construction and operation as well as vehicle manufacturing increase total CO emissions by 5-17 times from tailpipe performance for rail and 3-9 times for air.
A case study comparing the environmental performance of metropolitan regions is presented as an application of the inventory results. The San Francisco Bay Area, Chicago, and New York City are evaluated capturing passenger transportation life-cycle energy inputs and greenhouse gas and criteria air pollutant emissions. The regions are compared between off-peak and peak travel as well as personal and public transit. Additionally, healthcare externalities are computed from vehicle emissions. It is estimated that life-cycle energy varies from 6.3 MJ/PMT in the Bay Area to 5.7 MJ/PMT in Chicago and 5.3 MJ/PMT in New York for an average trip. Life-cycle GHG emissions range from 480 g CO2e/PMT in the Bay Area to 440 g CO2e/PMT for Chicago and 410 g CO2e/PMT in New York. CAP emissions vary depending on the pollutant with differences as large as 25% between regions. Life-cycle CAP emissions are between 11% and 380% larger than their operational counterparts. Peak travel, with typical higher riderships, does not necessarily environmentally outperform off-peak travel due to the large share of auto PMT and less than ideal operating conditions during congestion. The social costs of travel range from ¢51 (in ¢2007) per auto passenger per trip during peak in New York to ¢6 per public transit passenger per trip during peak hours in the Bay Area and New York. Average personal transit costs are around ¢30 while public transit ranges from ¢28 to ¢41.