Someone recently asked the Antiplanner whether electric trolley buses or buses powered by compressed natural gas (CNG) were a good alternative to light rail. My initial response was, “why do we need any alternative other than ordinary buses?” But I decided to take a look at the data in the 2012 National Transit Database to be sure that was an appropriate answer.
Five cities–Boston, Dayton, Philadelphia, Seattle, and San Francisco–still operate electric trolley buses. Ten major transit agencies fuel their buses exclusively or almost exclusively with CNG. Only one major transit agency uses liquid natural gas, and one uses a combination of CNG and LNG. Finally, five major transit agencies fuel their buses exclusively or almost exclusively with biodiesel.
My calculations for energy efficiency in BTUs per passenger mile and for greenhouse gas emissions in grams of CO2 per passenger mile are shown in the table below. The calculations are based on standard factors for BTUs per gallon of fuel and pounds of CO2 per million BTUs of fuel. For comparison, I’ve included the average of all motor buses, light rail, cars, and the Toyota Prius. The last column in the table shows passenger miles per vehicle revenue mile, or the average number of occupants on board the vehicle. In the table, “Electricity” refers to buses powered by overhead trolley wires.
