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The document outlines various financial mechanisms to transition the U.S. bus fleet away from diesel. It details federal programs managed by the DOT, DOE, and EPA, as well as state-specific initiatives in Texas, California, and New York, emphasizing that combining different grants can significantly reduce the incremental cost of advanced technologies like hybrid-electric buses.

The 2006 School Bus Pollution Report Card by the Union of Concerned Scientists finds that U.S. school buses are among the oldest vehicles on the road, with an average age of nine years, and emit nearly twice as much soot per mile as tractor-trailer trucks. The report grades states on tailpipe soot emissions, smog-forming pollution, and the success of their cleanup programs. While some states like California and Washington have made significant strides in reducing soot through retrofits and cleaner fuels, national soot pollution from school buses has only decreased by more than two percent. The document highlights the vulnerability of children to diesel exhaust, which is linked to asthma and lung growth deficits, and argues that substantial federal and state investment is needed for bus replacement and the installation of particulate traps.

The study identifies two primary sources of in-cabin pollution in conventional school buses: the tailpipe and the engine crankcase. It finds that while diesel particulate filters (DPF) combined with ultra-low sulfur diesel (ULSD) eliminate ultrafine particles, black carbon, and PAH, they do not reduce fine particulate matter (PM2.5) because that pollutant originates from the crankcase. The most effective solution for comprehensive elimination of all measured particles is the combination of a DPF, ULSD, and a Donaldson Spiracle closed-crankcase filtration device.

The report argues that California can significantly reduce its global warming impact by mandating the adoption of existing and near-term vehicle technologies. Modeling shows that currently available improvements in engines, transmissions, and air conditioning could reduce fleet average heat-trapping emissions by 20%, while advanced technologies available within five years could achieve a 40% reduction. These improvements are presented as cost-effective, with fuel savings offsetting initial costs within a few years, and would provide a model for other U.S. states and Canada.

The Hypercar concept, developed by the Rocky Mountain Institute (RMI), proposes a 'whole-system' approach to vehicle design to achieve fuel economies of 90 to 200 mpg. This is accomplished through the synergy of advanced polymeric composites to reduce mass by 50-65%, aerodynamic improvements to cut drag by 40-50%, and hybrid-electric drivesystems that recover up to 50% of braking energy. The document asserts that these vehicles can maintain safety standards, including in collisions with heavier cars, and could be compatible with various fuels, including hydrogen via fuel cells. RMI estimates that production-volume Hypercars could appear in the early 2000s, with costs comparable to conventional vehicles.

The SEI/UNEP Fuel Chain Project developed a methodology and software tool within the LEAP/EDB system to assess the full life-cycle environmental impacts of energy resources. By analyzing the 'chain' from extraction to end-use, the project aims to provide a more comprehensive comparison of fuel options than site-specific assessments. Case studies in Sri Lanka and Venezuela were used to validate the tool, focusing on biomass, coal, natural gas, and petroleum. In Sri Lanka, biomass was found to be environmentally superior to coal for electricity generation, while LPG was cleaner than biomass for household cooking. In Venezuela, natural gas was preferred over residual fuel oil for electricity, but its advantage over diesel for transport was mixed due to methane emissions and lower vehicle efficiency.

The transport sector in Pakistan is projected to see a 128% increase in greenhouse gas emissions between 2012 and 2030, rising from 35.4 MtCO2e to 80.7 MtCO2e. The document identifies several mitigation strategies, prioritizing efficiency norms for passenger vehicles, road-to-rail transfers, Bus Rapid Transit (BRT) systems, and improved car maintenance. Efficiency norms for passenger cars, taxis, and vans are identified as the highest priority, with a potential reduction of 7.45 MtCO2e by 2030. Shifting freight and passengers from road to rail is another key strategy, though rail's share of freight has dropped to under 1%, with a national target of 20%. The expansion of BRT systems in cities like Karachi, Lahore, Rawalpindi-Islamabad, and Multan is also highlighted as a means to improve urban mobility and reduce emissions.

The document examines the transition from diesel-powered transit buses to hybrid-electric alternatives, highlighting significant reductions in emissions and fuel consumption. It details the technical differences between series and parallel hybrid configurations and analyzes the financial barriers to adoption, noting that while hybrid buses have a higher purchase price, federal grants and lower operational costs mitigate these expenses. By 2006, over 900 hybrid buses were in service across more than 40 North American transit agencies.

The document uses a System Dynamics simulation model to project the Colombian vehicle fleet's evolution from 2025 to 2050. It finds that while annual GNV consumption is projected to decrease by approximately 43% by 2050, the fuel will not disappear on its own due to systemic inertia and the gradual replacement of vehicles. The analysis highlights that traditional buses may actually see an increase in GNV vehicles due to decentralized decision-making and high initial costs of electric alternatives. Cumulatively, the transport sector would demand over 40 billion cubic meters of GNV and emit more than 70 million tonnes of CO2 equivalent by 2050, which represents a significant portion of Colombia's NDC 3.0 commitments. The brief concludes that maintaining GNV demand creates a financial burden of over 200 trillion constant pesos and pressures limited national gas reserves, suggesting that a clear public direction toward zero-emission technologies is necessary to avoid long-term fossil fuel lock-in.

The document outlines a technical framework for calculating fuel use across various truck types—including tractor-trailers, straight trucks, and cargo vans—using data from the Freight Analysis Framework (FAF) and the Vehicle Inventory and Use Survey (VIUS). It establishes baseline fuel economies (e.g., 5.8 mpg for tractor-trailers) and projects improvements by 2025 based on technology packages such as aerodynamic devices and hybrid-electric powertrains. Additionally, it applies these methodologies to estimate the current fuel use and future savings for the fleets of UPS, FedEx, PepsiCo, The Coca-Cola Company, and Walmart.

The World Resources Institute (WRI) evaluated a sludge-to-energy project in Xiangyang City, China, which utilizes high-temperature thermal hydrolysis and anaerobic digestion. The project achieves significant environmental gains, including the recovery of 96% of nitrogen and 99% of phosphorous, and the reduction of greenhouse gas emissions by 95% to 98% compared to landfilling and incineration. Over a 21-year period, the project is expected to produce 45.4 million m3 of natural gas, replacing 60,000 m3 of gasoline and further reducing CO2e emissions by 140,000 metric tons. Economically, the project's success is attributed to a 'government-bank-enterprise' partnership involving the municipal government, KfW Bankengruppe of Germany, and the Export-Import Bank of China, alongside a market-oriented design focusing on the sale of compressed natural gas (CNG) and biochar.

The paper examines how 29 Clean Cities and Communities (CC&C) coalitions, overseen by the US Department of Energy, facilitate the adoption of electric school buses (ESBs) in the US. While coalitions generally support ESBs for health and environmental reasons, their effectiveness is limited by capacity constraints, infrastructure gaps, and political tensions regarding alternative fuels like propane and compressed natural gas.

The document argues that the auto-rickshaw sector can support sustainable urban transport in India by providing first-and-last-mile connectivity and door-to-door alternatives to private vehicles. To achieve this, it recommends shifting from two-stroke to four-stroke engines to reduce PM10 emissions, implementing separate emission standards for HC and NOx, and improving vehicle design and road infrastructure to enhance occupant safety.