Is the GHG reduction from operating an electric vehicle (EV) offset by the production of electricity used to charge it?     [Ray M.]

An electric vehicle is only as green as the source of electricity that is used to charge it. The same is true for a gasoline fueled car, gasoline derived from tar sands will contribute more GHG emissions   than  petroleum from conventional drilling.   Besides the fuel source,   other important factors matter for GHG emissions  such as car aerodynamics, weight, size and how efficient a car is driven.

According to the DOE,  a Prius hybrid (which burns gasoline when its batteries are not engaged ) and a Nissan Leaf (EV)  both emit 200 grams/mile of GHG using a US average for source of electricity generation of which 30% is coal.    If  one uses electricity from California with a higher mix of renewables the EV could have only 100 grams/mile or only half what the hybrid emits. On the other hand if coal is the electricity source the EV could emit 300 grams/mile or more than the hybrid.

So what is really needed to reduce operating GHG emissions from transportation is more EVs along with production of electricity from fossil fuel free sources such as wind, solar and hydro. There are other considerations for EVs and GHG emissions. Currently it takes more energy to produce an EV due to its large batteries and higher use of aluminum body panels.  This higher energy use could come down as EV volumes are ramped up and battery design and efficiency is improved. Work is ongoing to recycle the older batteries giving them a second life.

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