The Obama administration recently gave the Nissan Leaf plug-in electric vehicle a mileage rating of 99 MPG. That makes it look very good compared to almost any gasoline-powered vehicle. But what does an MPG rating even mean on an electric vehicle? And is it a fair comparison of the energy consumption of the Nissan Leaf to a gasoline-powered vehicle?
Many folks are skeptical of the benefits of all-electric vehicles. In fact, there are very good reasons to wonder about the wisdom of producing them at all. This debate is completely overshadowed, however, by the loud support that all-electric vehicles get from the usual suspects in the environmental wacko world, and from the Obama adminstration and their lapdog lamestream media.
So what's the actual truth here? Warren Meyer, of Coyoteblog fame, has an excellent analysis in the current issue of Forbes. If you're curious (and you should be, as your tax dollars are subsidizing GM's Volt), read it and understand...
I was talking about hybrid electric and all-electric vehicles over our Thanksgiving meal with a young chemical engineering student. I forwarded the link to this blog to him. His response follows:
ReplyDeleteHi there Simon, this is Josh!
It's funny that you should mention this; we were just learning about the efficiencies of various types of motors and powerplants in my Energy class this quarter. The average coal-powered electric powerplant has an efficiency of only 34%, and approximately 32% with transmission losses, this is true; however, the article also forgot that an electric motor is only about 40% efficient in converting electric energy to kinetic energy. So, the total efficiency of the electric car is about 13%! In comparison, a gas car isn't much better, at an efficiency of about 15-25%. I'm not sure if Nssan took this into effect for their 99mpg mileage estimate, but if they didn't, the car would only be getting a combined mileage of about 12mpg total energy equivalent. Then, what about the disposal and replacement of the batteries? It keeps going on and on... I think I'll stick with diesel! Due to the higher compression ratio they get better thermal efficiency than gas motors, and thus run from 25% to 40% total efficiency, and can be run on independent fuel sources, not to mention diesel's higher energy density. Thanks for the article! I wish more people were aware of these issues...
Josh