SummaryThe formation of effective policies to reduce emissions from goods movement should consider local and remote life cycle effects as well as barriers for mode shifting. Using uniand multimodal freight movements by truck, rail, and ocean-going vessel (OGV) associated with California, a life cycle assessment (LCA) is developed to estimate the local and remote emissions that occur from freight activity inside and associated with the state. Long-run average per tonne-kilometer results show that OGVs emit the fewest emissions, followed by rail, then trucks, and that the inclusion of life cycle processes can increase impacts by up to 32% for energy and greenhouse gas (GHG) emissions and 4,200% for conventional air pollutants. Efforts to reduce emissions through mode shifting should recognize that infrastructure and market configurations may be inimical to mode substitution. A uniand multimodal shipping emissions assessment is developed for intrastate and Californiaassociated freight movements to illustrate the life cycle impacts of typical trips for certain types of goods. When targeting GHG reductions in California, it should be recognized that heavy-duty trucks are responsible for 99% of intrastate goods movement emissions. An assessment of future freight truck technology improvements is performed to estimate the effectiveness of strategies to meet 2050 GHG reduction goals. Whereas aggressive improvements in fuel economy coupled with alternative vehicles and fuels can significantly reduce GHG emissions, to meet 2050 goals will likely require zero carbon emission vehicle technology. The value of using LCA in GHG reduction policy for transportation systems is explored. Keywords:air pollution freight transportation goods movement greenhouse gas policy industrial ecology life cycle assessment (LCA)
SummaryReductions in the greenhouse gas (GHG) intensity of passenger and freight transportation are possible through adoption of fuel-saving technologies, demand switching between modes, and large-scale electrification of fleets, in addition to other actions. In this study, future scenarios to 2030 and 2050 are the basis for assessment of GHG reduction potentials for major passenger and freight modes (automobiles, buses, trains, aircraft, and oceangoing vessels) across eight regions of the world. New fuel-saving technologies can significantly reduce the life-cycle GHG footprint of both passenger and freight vehicles, but not uniformly worldwide. Countries outside of the Organization for Economic Cooperation and Development (OECD) lag behind OECD countries in GHG reduction potentials for all modes but oceangoing vessels owing to a combination of slower adoption of fuel-saving technologies and a slower decarbonization of electricity generation and other processes. The reduction of GHG intensity will occur more slowly for freight modes than for passenger modes. However, improved fuel efficiency has negative feedbacks to the effectiveness of mode-switching and alternative fuel adoption policies through 2050 because improvements in the fuel efficiency of vehicles alone may cause the marginal benefits of GHG abatement policies to diminish over time. This trend may be reversed if alternative fuel pathways decarbonize at faster rates than conventional transportation fuels. The largest opportunities for GHG reductions occur in non-OECD countries. Given the many factors that distinguish transportation systems between developed and developing nations (e.g., availability of new technologies, the financial ability to acquire them, and policies to incentivize their adoption), many benefits could be gained through interregional cooperation.
The life-cycle output (e.g., level of service) of infrastructure systems heavily influences their normalized environmental footprint. Many studies and tools calculate emission factors based on average productivity; however, the performance of these systems varies over time and space. We evaluate the appropriate use of emission factors based on average levels of service by comparing them to those reflecting a distribution of system outputs. For the provision of truck and bus services where fuel economy is assumed constant over levels of service, emission factor estimation biases, described by Jensen's inequality, always result in larger-than-expected environmental impacts (3%-400%) and depend strongly on the variability and skew of truck payloads and bus ridership. Well-to-wheel greenhouse gas emission factors for diesel trucks in California range from 87 to 1,500 g of CO2 equivalents per ton-km, depending on the size and type of trucks and the services performed. Along a bus route in San Francisco, well-to-wheel emission factors ranged between 53 and 940 g of CO2 equivalents per passenger-km. The use of biased emission factors can have profound effects on various policy decisions. If average emission rates must be used, reflecting a distribution of productivity can reduce emission factor biases.
Passenger cars in the United States (US) rely primarily on petroleum-derived fuels and 16 contribute the majority of US transportation-related greenhouse gas (GHG) emissions. 17 Electricity and biofuels are two promising alternatives for reducing both the carbon intensity of 18 automotive transportation and US reliance on imported oil. However, as standalone solutions, 19 the biofuels option is limited by land availability and the electricity option is limited by market 20 adoption rates and technical challenges. This paper explores potential GHG emissions 21 reductions attainable in the US through 2050 with a county-level scenario analysis that combines 22 ambitious plug-in hybrid electric vehicle (PHEV) adoption rates with scale-up of cellulosic 23 ethanol production. With PHEVs achieving a 58% share of the passenger car fleet by 2050, 24 phasing out most corn ethanol and limiting cellulosic ethanol feedstocks to sustainably produced 25 crop residues and dedicated crops, we project that the US could supply the liquid fuels needed 26 for the automobile fleet with an average blend of 80% ethanol (by volume) and 20% gasoline. If 27 electricity for PHEV charging could be supplied by a combination of renewables and natural-gas 28 combined-cycle power plants, the carbon intensity of automotive transport would be 79 g CO 2 e 29 per vehicle-kilometer traveled, a 71% reduction relative to 2013. 30 31 batteries or an energy-dense liquid fuel. Current US passenger cars rely almost entirely on 37 petroleum. 1 Passenger cars make up the single largest share of all transportation-related GHG 38 emissions in the US, releasing 758 Tg/y of CO 2 e in 2010. 2 To meet GHG emissions reduction 39 goals will require both reductions in vehicle-kilometers traveled (VKT) and decarbonization of 40 fuels. 3-5 41 42 Electricity derived from low-GHG sources and biofuels are two promising options for achieving 43 GHG intensity reductions in transportation. However, both have drawbacks that make them 44 undesirable standalone replacements for conventional fuels. Electrification of transportation 45 must overcome limited vehicle battery capacity, incomplete charging infrastructure, lengthy 46 charging times, and the need for significant reductions in the carbon intensity of electricity 47
Climate change is making water supply less predictable, even unreliable, in parts of the world. Urban water providers, especially in already arid areas, will need to diversify their water resources by switching to alternative sources and negotiating trading agreements to create more resilient and interdependent networks. The increasing complexity of these networks will likely require more operational electricity. The ability to document, visualize, and analyze water-energy relationships will be critical to future water planning, especially as data needed to conduct the analyses become increasingly available. We have developed a network model and decision-support tool, WESTNet, to perform these tasks. Herein, WESTNet was used to analyze a model of California's 2010 urban water network as well as the projected system for 2020 and 2030. Results for California's ten hydrologic regions show that the average number of water sources per utility and total electricity consumption for supplying water will increase in spite of decreasing per-capita water consumption. Electricity intensity (kWh m −3 ) will increase in arid regions of the state due to shifts to alternative water sources such as indirect potable water reuse, desalination, and water transfers. In wetter, typically less populated, regions, reduced water demand for electricity-intensive supplies will decrease the electricity intensity of the water supply mix, though total electricity consumption will increase due to urban population growth. The results of this study provide a baseline for comparing current and potential innovations to California's water system. The WESTNet tool can be applied to diverse water systems in any geographic region at a variety of scales to evaluate an array of network-dependent water-energy parameters.
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