We’ve all been entertained by the 100-230 MPG mileage claims for gasoline/electric hybrid cars. It’s entertaining because nobody agrees on how to calculate MPG when the gasoline engine may run from 0% to 100% of the time. In the first instance the MPG is infinite. In the second it equals a normal gasoline engine.
We do know a few other things, though. The typical claim for range on electricity alone for a plug-in vehicle is about 40 miles (Chevy Volt). After that it needs gas to go. The more miles you drive without a plug-in recharge the lower the gasoline mileage you get for your trip.
So let’s concentrate on the electric powered part of the cycle. Assuming a 40 mile range, how much coal needs to be burned in typical power plant to power the Volt for 40 miles? An easy way to estimate this is to use the Volt’s battery capacity, which is 16 KWH. The typical coal fired power plant running at 40% efficiency produces 2,460 KWH per ton of coal. So (ignoring transmission losses) 16/2,460 = .0065 (tons/40 miles) x 2000 (lbs/ton) = 13 Lbs. of coal per 40 miles driven.
Now, suppose every car in the USA were a Volt driven only 40 Miles per day as the environmental dreamers dream about. That would require 135 million autos (2006 count) x 13 lbs / 2,000 lbs = 87,750 tons of coal per day, or 32 million tons per year. In the U.S.A. about 1,146 million tons of coal are produced per year.
In 1994 it is estimated that U.S. “residential” vehicles traveled 1.74 Billion miles. If this were to be done under electric power using today’s efficiencies, as above, this would require 565 million tons of coal per year, a 50% increase compared to current production.
Oh-oh! The Greenies will be offended and angered. How dare we assume that all this transportation electricity will come from coal? Well, we can be completely assured about one thing. It won’t come from wind and solar and bio-mass. Only nuclear or coal are capable of producing this much juice. But nukes take many years to build (thanks largely to constant, niggling lawsuits by greenies), so even nuclear plants won’t be a quick solution. This leaves coal or natural gas.
Conclusion: There’s nothing wrong with electricity, nothing wrong with petroleum, nothing wrong with coal, but you don’t get something (like 240 MPG) for nothing. And nuclear may be needed. If it isn’t all nonsense in the first place.
(P.S. I’ve never claimed to be a math whiz, so you’re welcome to check my calculations. And actually, I think hybrids are really keen, but the hype about energy and CO2 is pure political bull.)