Dive Brief:

• Battery-electric buses have noticeable environmental benefits over diesel and natural gas buses in the form of fewer greenhouse gas emissions, even when taking into consideration the electricity generated to operate and charge the buses, according to a study by the Union of Concerned Scientists.
• The study examined electricity generation in all parts of the country and factored that into the environmental friendliness of electric buses throughout their lifecycle. It found that when averaging results from across the country, electric battery buses are 2.5 times cleaner in terms of lifecycle emissions than diesel buses.
• Operating electric buses on the West Coast is the cleanest because of the amount of hydro, wind and solar power used to generate electricity there. Places like the Midwest that still use coal power have more emissions for generating the electric buses' electricity, yet the emissions produced are still fewer than operating diesel buses.

Dive Insight:

The study notes that more than 85 transit agencies throughout the country have begun adding electric buses to their fleets. The number has grown quickly just in the last year, with cities including Dallas, St. Louis, MO, New York City and Washington, DC all investing in some electric buses. The federal government recently granted $264 million to cities to improve their bus systems, with a significant portion going toward adding electric buses.

Electric buses are lauded not just for their lower emissions but also for being quieter and having lower operating costs than diesel and natural gas buses. 

This study is interesting because it considers the environmental effects of generating the electricity used to power the buses. A lot of other research solely looks at the emissions from the buses themselves, which doesn't necessarily provide a complete analysis of the vehicles' effects.

One lifecycle factor that the study did not include, though, is end-of-life battery disposal. "This analysis focused on direct global warming emissions during the production of fuel and operation of the bus," Jimmy O'Dea, senior vehicles analyst at UCS and study author, told Smart Cities Dive.

Although battery-electric vehicles create fewer emissions, they do create waste if the vehicle outlives a battery and therefore require a new one. Electric batteries are lasting longer and longer as the technology advances, but the average standard electric car battery still is only estimated to function optimally for 8-10 years, and factors like high temperatures can shorten life. The average useful life of a bus in the United States is 12 years.

Even so, researchers view electric-battery buses as a more long-term environmentally friendly option than diesel or natural gas buses. Plus, research and development on electric vehicle batteries is advancing new uses for the spent batteries as well as better recycling options.

"Battery recycling and disposal is a smaller greenhouse gas issue compared to the rest of the lifecycle of the bus, but it is an important consideration as more and more electric vehicles hit the road," O'Dea said. "I’m encouraged to see many companies considering secondary uses for batteries after they reach the end of their useful life in a vehicle and other companies exploring the recycling of battery materials. This is encouraging because re-purposing spent fuel is not an option we have with combustion vehicles."