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As interest in hydrogen as an energy carrier has increased, the various ways that hydrogen is made are being categorized as “green,” “blue,” “gray,” and other colors in relation to their environmental impact. While these categorizations are somewhat useful to indicate the environmental and climate change impacts of different production pathways, they are not especially useful for policy making or industry decisionmaking purposes because they are subjective. For example, most definitions of green pathways for hydrogen production only include electrolysis from renewable electricity sources; however, Figure 1 indicates additional production pathways with some of these having near-zero or even negative greenhouse gas (GHG) emissions as well as low or no other emissions of concern. To help clarify the role of hydrogen in decarbonizing California, this brief summarizes the latest scientific findings from recent and in-progress research across the University of California Institute of Transportation Studies (UC ITS) concerning the relative carbon intensity (CI) of hydrogen production pathways. It also briefly covers the availability of biomass and biogas in California that could be applied to the production of low-CI hydrogen.

Supplemental material, sj-pdf-1-trr-10.1177_03611981221101896 for Life-Cycle Approach to Healthy Airport Terminal Buildings: Spatial-Temporal Analysis of Mitigation Strategies for Addressing the Pollutants that Affect Climate Change and Human Health by Fiona Greer, Arpad Horvath and Jasenka Rakas in Transportation Research Record

In 2015, California established a mandate that requires on-road greenhouse gas (GHG) emissions to be reduced by 40% below 1990 levels by 2030. We explore the feasibility of meeting this goal by large-scale commercialization of drop-in biofuels. Drop-in biofuels, although not clearly defined, are a class of fuels that can be produced from biomass and blended with either crude oil or finished fuels without requiring equipment retrofits. This article focuses on thermochemical routes at or near commercialization. We provide a bottom-up, spatially explicit cost analysis to evaluate whether California can meet its 2030 GHG reduction target with drop-in fuels alone. A takeaway from our analysis is that drop-in fuels, if their performance is consistent with small-scale and simulated results, can be viable low-carbon substitutes for gasoline and diesel. We find that California can meet, and even exceed, its 2030 GHG emissions target for on-road vehicles with drop-in biofuels alone, but this requires use of biomass resources located outside the state. Meeting the 40% reduction target in a cost-effective manner requires pyrolysis of herbaceous agricultural residues (96% of total fuel output) and the conversion of woody residues via methanol-to-gasoline (4%). This scale of production would require 58 million metric tons of biomass feedstock, or 20% of total available biomass residues in the United States. For comparison, California is responsible for 11% of transportation-related petroleum consumption in the US. The approximately 5 billion gallons (19 billion liters) per year of drop-in fuel would displace 30% of gasoline and 60% of diesel demand in California. If electricity offset credits are eliminated, the target can be met with a similar scale of production, but methanol-to-gasoline becomes the dominant route (>99%), biomass requirements increase by 33%, and average production costs increase by 20%. Following this policy pathway would increase national biofuel production by 30% relative to 2015 production levels.

Vehicle manufacturing effects are critical life-cycle components in the total costs of vehicle travel and future manufacturing processes should be evaluated for travel forecasts. With efforts to introduce lightweight materials, increased fuel economy, and new technologies such as electric vehicles, understanding the energy and environmental effects of these expected vehicles is critical. Current vehicle manufacturing energy use and greenhouse gas emissions are summarized from existing research for passenger (conventional gasoline vehicles, hybrid electric vehicles, aircraft, high-speed rail) and freight (trucks, trains, and ocean going vessels) modes. Future vehicle manufacturing effects are then determined incorporating the aforementioned modes as well as plug-in hybrid and battery electric vehicles.

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). 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). 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 passenger transportation modes of rail and air are critical systems relied upon for business and leisure. When considering their environmental effects, most studies and policy focus on the fuel use of the vehicles, and ignore the energy and other resource inputs and environmental outputs from the life cycles of other components. Vehicle manufacturing and maintenance, infrastructure construction and operation, and fuel production are rarely included in environmental factors for transportation systems. The goal of this project is to develop a comprehensive life-cycle assessment model to quantify the energy inputs and emissions from rail and air transportation in the U.S. associated with the life-cycle components (raw materials extraction, manufacturing, construction, operation, maintenance) of the vehicles, infrastructures, and fuels involved in these systems. Energy inputs are quantified as well as greenhouse gas and criteria air pollutant outputs. Inventory results are normalized to effects per passenger-mile traveled. Results show that energy and greenhouse gas emissions increase by as much as 2.1 times for heavy rail, 1.4 times for high speed rail, and 1.3 times for air when life-cycle components are included. Criteria air pollutant emissions increase between 1.1-29 times for heavy rail, 1.2-1.4 times for high speed rail, and 1.5-9 times for air.

This paper presents a discussion directed at determining the most progressive options for shifting the freight logistics industry towards having more sustainable-oriented goals. The authors first discuss transportation sustainability and the concept of green logistics. This is followed by a discussion on externalities resulting from vehicle emissions and indirect environmental externalities. The problem of environmental externalities is then examined, with focus on emissions and other related data. The authors then examine options for reducing environmental externalities. They discuss impact considerations, options focused on emissions reduction, changing freight sector operations, and considerations regarding demand and economic development.

The public, industry and governments have become increasingly interested in green design and engineering as approaches towards better environmental quality and sustainable development. Pavement construction is one of the largest consumers of natural resources. Recycling of pavements represents an important opportunity to save the mining and use of virgin materials, conserve energy, divert materials away from landfills, and save scarce tax dollars. How much pollution, energy, natural resources, and money could be saved by using secondary materials in road construction? What are the engineering limits of using recycled materials in roads? Can we recycle over and over again pavements that contain rubber, glass, and other secondary materials? This research will quantify the environmental and economic costs and benefits of recycling asphalt pavements, and using secondary materials for their construction. The impacts will be traced through the related life-cycles and supply chains for material and energy inputs, water consumption, hazardous and non-hazardous waste generation, toxic discharges, and greenhouse gas as well as particulate matter emissions. Life-cycle environmental and economic assessment methods will be coupled with construction process models. Stakeholders will be able to use the resulting computer tool for decision-making and scenario analysis as parameters of the pavement recycling model change over time and from region to region.

Environmental performance measurement is a key corporate challenge in an era of global competition, rapid technological change and increasing concern for the environment, health and safety. Industry has made major strides in reducing environmental burdens associated with products and processes. This paper describes an approach to tracking toxic releases and associated risks over time based upon the data of the Toxics Release Inventory (TRI) and relevant toxic indices. We provide examples for companies, an industry, and products. We discuss how this environmental performance methodology can be used in green design and manufacturing efforts.