This afternoon I was invited by the Unitarian Universalist Church in Palo
Alto to give a talk on global energy based on A Cubic Mile of Oil. It was great to see many familiar faces and I thoroughly
enjoyed the discussion following the presentation. The slides I showed and many
more that I held in reserve are available here.
During the Q&A I was asked how CO2 emissions
from electric cars compare with those from a gasoline-powered car if one takes
into account emissions associated with electricity production. I responded by
saying that in general CO2 emissions from electric vehicles are
lower than those from gasoline-powered cars, but it really depends on the
specifics—particularly on the location because grid emissions per kWh vary
considerable across the country depending on the fuel mix used to produce the
electricity. Here is a link to a NY
Times article that I mentioned during the talk. It shows the required fuel
efficiency of a car to have emissions equivalent to a Nissan Leaf that is
charged in different parts of the country.
As the graphic
illustrates, in many parts the country the required fuel efficiency is in
excess of 50 mpg, which is higher than the fuel efficiency of even hybrid cars,
but in much of central USA, where a larger percentage of electricity is
produced from coal, the required efficiency of 35 mpg is easily surpassed by
many fuel efficient cars.
Thanks for the link. Another important factor in assessing the relative efficiency of electric cars is to look at the full lifetime of the car. While the grid continues to get cleaner, the fuel we put in gas cars will continue to come from more extreme - dangerous and costly - energy sources (such as deep water drilling and tar sands). And unfortunately there still aren't many gas cars on the market that do better than 35mpg. When purchasing a new car, it's important to think about what kind of commitment we want to be making to our transportation infrastructure over the next (ultra critical) ten years.
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