Environmental and economic assessment of alternative bus powertrains. Insights from the literature

Urban buses provide an important contribution to decreasing the number of private cars on the roads, reducing congestions and lowering air emissions. However, most of the circulating buses are still powered by internal combustion diesel engines, whose environmental performance is much worse than that of alternative powertrains such as electric or hydrogen fuel cell buses. The chapter reviews the most recent studies aiming to provide answers to questions such as what is the economic and environmental performance of different bus powertrains; what lesson can we learn from jointly considering the economic and environmental aspects; and what are the chances that the more environmentally friendly bus powertrains will prevail in the short and medium term. The main findings are that main advantage of fossil-fuel based buses are their much lower acquisition bus costs. Electric and hydrogen fuel cell buses require much higher initial costs not only for the bus acquisition but also for the charging\refuelling infrastructure. However, the initial capital disadvantage could be, under certain conditions, compensated by the lower annual operating cost, thus making them competitive in terms of total cost of ownership. There is a sufficiently large consensus that electric, hydrogen fuel cell buses and the biomethane-fuelled buses could reduce the environmental impact of bus operation relative to diesel counterpart along all environmental impact dimensions. According to some others authors, the monetarized environmental benefits from alternative powertrains are sufficiently high to compensate for their higher monetary costs.