Plug-in vehicles? What about fuels burned in the grid?
November 28th, 2008 by Jim JustGovernor Kulongosk’s transportation package proposes substantial subsidies for plug-in hybrid and all-electric vehicles. The details weren’t revealed in the Transportation Plan, but his 2009 climate change agenda released earlier proposes to replace the $1,500 tax credit on hybrid vehicles with a $5,000 credit on all-electric cars.
As discussed here, Kulongoski’s plan fails to address where the electricity to recharge electric vehicles would come from or how the transmission system could handle the additional load were electric vehicles to make any significant contribution to our automobile fleet.
The intent of electric vehicles is to save energy, save running cost, and reduce the carbon footprint. Engineer J. David Cohen argues that electric vehicles do none of this.
What is going on here? It’s actually quite simple. If the owner of this modified vehicle, such as a Toyota Prius, plugs his vehicle into the wall, he is using high energy cost electricity from the grid to recharge the battery. The electrical energy is on average about 50 percent derived from the combustion of coal, 20 percent from the combustion of natural gas, and 1 percent to 3 percent from the combustion of fuel oil. In addition, the thermal efficiency at plug-in is only about 33 percent. Another 12 percent is lost in the recharging process and running resistance effects. This leaves us at about 21 percent, and is around 9 percent less than the Prius is normally capable of with gasoline alone as its energy source.
The bottom line is that the first 40 miles of driving has produced more CO2 and has cost very close to the same in electrical energy as the roughly 0.9 gallon of gasoline that is saved. (The comparative numbers vary with the local costs of gasoline and electricity.) The only way this technology could work is if the recharge is done with renewable energy technology such as an adequate solar photoelectric panel array. The $10,000 upfront battery cost and the solar array installation cost will never be recovered.
In Oregon the percentage of electricity generated by coal is a little lower than the 50% figure used by Cohen – 41%, with natural gas another 10%. But the principle is the same. And if demand for electricity were to increase to power electric cars, where would the additional electricity come from? Unless it came from a renewable source, none of which are on the horizon in Oregon, we’re not eliminating or even significantly mitigating climate impacts.
You can’t make a case for electric vehicles without accounting for the coal, gas, or oil burned in the electric grid.