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.