News | PSR Researcher Scott Samuelsen Assesses the Impacts of Alternative Urban Bus Technologies in Southern California

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by Brittany Cooper and Jenny Benitez


In order to accomplish California’s ambitious climate target of full carbon neutrality by 2045state leaders are making great strides by implementing clean energy policies to target the largest emission sources. According to 2018 data, 40% of California’s emissions were reported to come from transportation, stimulating the state’s push for a transition to electric vehicles in conjunction with carbon-free electricity. As transit agencies seek to meet these state carbon goals, they are looking to alternative technologies such as battery electric buses (BEBs) and hydrogen fuel cell electric buses (FCEBs) to replace the conventional buses currently in circulation. Switching away from fossil fuels is an important step in improving air quality and reducing transportation’s impact on the environment, but there is still the question of which innovation has the greater environmental impact and more feasible cost. In the PSR-affiliated project, “Life Cycle Assessment of Environmental and Economic Impacts of Deploying Alternative Urban Bus Powertrain Technologies in the South Coast Air Basin,” UC Irvine Professor Emeritus Scott Samuelsen, Assistant Professional Researcher Brian Tarroja, and Graduate Student Analy Castillo Munoz, set out to assess these monetary costs and environmental impacts in the area covering Orange, Riverside, San Bernardino, and Los Angeles counties. Their detailed study considers the entire life cycle of a bus in order to help agencies “cost-effectively meet environmental objectives in California.”   


Research demonstrates that both alternative bus powerhouse methods - BEBs and FCEBs - reduce pollution when compared to conventional urban buses, yet the size of the overall benefits depends on the electricity generation sources. Powering alternative buses with an electric grid that contains fossil fuels, such as the current California grid mix, notably reduces the overall environmental benefits. The study found that if the California grid mix - i.e. a mix including fossil fuels - was used to power BEBs and FCEBs, BEBs would be the more efficient option. However, the researchers stress the importance of powering the electric buses with fossil fuel-free energy in order to ensure environmental impact. It remains clear though that alternative buses are an improvement from traditional urban buses and a better option for clean air quality.   

When analyzing the costs with current figures, the study found that both alternative bus methods are currently more expensive than traditional buses. The factors contributing to these costs include the initial purchase, fueling infrastructure development, and the price of fuel or electricity. In fact, the total cost of owning the alternative technologies was found to be highly sensitive to the cost of electricity, with the rapid evolution of the electricity system having strong implications for the economic comparison between BEBs or FCEBs, as well as conventional bus transport. If the costs of the alternative buses are considered over their life cycle, Samuelsen and his team demonstrate that the cost becomes less than or equal to that of an urban bus since implementation costs are spread over increased usage. While the current cost analysis may not instill optimism in the transition to a fully electric fleet, the authors highlight that the rapid changes in the electricity system, the anticipated falling cost of renewables, and the expected economy-of-scale improvements for both alternative technologies would lower the future costs of operation. 


Transportation’s reliance on fossil fuels has made the industry a heavy contributor to greenhouse gas emissions, making it critical for the industry to advance technologically. In order to encourage the implementation of these alternative buses, the authors argue that it is important to help reduce the costs through aid and subsidies. The researchers suggest incentives such as subsidizing electricity rates for BEBs, especially in areas of the South Coast Air Basin where poor air quality poses health risks for the large resident populations. While the reduction in greenhouse gas emissions and pollutants varies between BEBs and FCEBs, alternative bus powerhouse methods are ultimately a step in the right direction towards California’s environmental goals.