Solar Powered Cars?

 I’ve been monkeying with energy statistics long enough to know that, as with any statistics, with enough ingenuity you can find some number somewhere to prove your point. My goal on this blog has not been to prove points but rather to learn and maybe to teach. Today I set out to learn a little about the future of electric vehicles.

It seems likely that a material portion of the automotive fleet in the U.S. will consist of electric vehicles in the next 20 to 30 years. I haven’t done a forecast of the electric vehicle market, but many others have (for example here and here).

Others have also shown that electric vehicles can be less polluting than internal combustion engine vehicles–even if the electricity is produced by burning fossil fuels–because electric motors are more efficient than gasoline engine in converting stored energy to motion.

So I was wondering whether renewable energy sources like solar and wind might ever power a significant amount of our driving. My highly superficial analysis suggests that’s plausible but far in the future.

Consider this: it is estimated that today’s electric vehicles will travel a mile on between .2 and .4 kilowatt hours of electricity.

Last year, according to the Federal Highway Administration, U.S. residential vehicles travelled some 2,922 billion miles. According to the Energy Information Administration (EIA), some 843 MW hours of solar energy and some 52,000 MW hours of wind energy were generated in the U.S. last year. Together that’s enough to power about 176 billion miles of driving, or just about six percent of the total. Little to none of that electricity was actually used to power electric vehicles, though. The EIA says that in 2007, the most recent year for which I could find figures, all electric vehicles consumed just 168 MW hours of electricity.

Today, wind and solar account for a relatively small share of the country’s supply of renewable energy; hydropower is the largest source, and there will be very little hydropower capacity added in coming years. The EIA expects that our supply of renewable energy will nearly double by 2030 compared to 2007 levels, with growth led by solar and biomass. If half of that increase is used to power electric vehicles, assuming their efficiency doesn’t improve (a conservative assumption), that will be enough to power them for nearly 500 billion miles, a substantial share of the total.

It seems plausible, therefore, that renewably generated electricity could power a significant portion of the country’s driving needs over the next decades. Whether strong demand for plug-in electric vehicles will develop remains uncertain, of course. And like any analysis of the country’s energy needs, this one suggests that energy will continue to come from a broad mix of sources for the foreseeable future.

I welcome your perspective on the electric vehicle future and the role of renewables in it.

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Filed under biofuels, efficiency, solar, transportation

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