Monday, April 4, 2011

It's electric! But still emits carbon?

Ecometrica has released a new technical paper detailing the amount of carbon emitted due to electric car use in the UK. The report is available here for download. "But wait, I thought electric cars were zero emission?" They are - but of course there are carbon emissions resulting from the generation of electricity that charges and powers the vehicles.  

Ecometrica first calculated the amount of electricity required to power an electric car for every mile driven and combined this information with measures of carbon emissions produced for ever kilowatt of electricity consumed in the UK. They accounted not only for energy consumed at the charging station, but also energy consumed in the transmission and distribution of electricity across the UK power grid.

The paper concludes that use of an electric car in the UK results in the emission of 75 gCO2/km. This amount is lower than any car in production today, including the hybrid Toyota Prius which emits roughly 89 gCO2/km (the average UK car emits 208 gCO2/km).

Interestingly, the same car driven in the U.S. would result in more carbon emissions (84 gCO2/km). This effect is due to the proportion of carbon emitting sources of electricity generation relative to nuclear and renewable electricity generation in different countries.  In other words, the charging stations in England use lower carbon intensity electricity generating sources than do those in the U.S. As another example, an electric car in China would result in more carbon emissions (118 gCO2/km) than a diesel engine car (99 gCO2/km), because most of the power stations in China are coal fired - the most carbon intensive form of electricity generation.

This report sheds interesting light on the complexity of looking to data to determine what we are truly getting from the green products hitting the market - and it's not always a (carbon) free ride.

- Blake Hudson

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