Friday, March 6, 2009

Optimal Battery Range for Plug-in Hybrid Cars

I've long maintained that the best way to move on a shoestring from all-gasoline cars to zero-gasoline cars is to implement short-electric-range (5 to 10 mile) plug-in hybrids immediately. Months ago I researched nationwide daily commutes at the Census Bureau and concluded that a modest range around 10-miles would serve about 28% of commuters. But the buzz from automakers for the past six months has been that their first marketed hybrids will have battery ranges on the order of 40 miles.

You take what you can get. So I've been happily anticipating my 40-mile-electric-range hybrid in spite of the nagging feeling it wasn't the best way to move forward quickly.

Now the Carnegie-Melon Institute has reported that 7 miles is the optimal battery range for urban drivers:
"We looked at a wide range of scenarios from fluctuating gasoline prices to new battery technology and carbon taxes. The core conclusion is consistent: For urban drivers who charge frequently - every 20 miles or less - plug-in vehicles with small battery packs sized for about 7 miles of electric travel per charge can reduce gasoline consumption, greenhouse gas emissions and lifetime cost. For those who can't charge often, large-capacity plug-in vehicles sized for 40 or more miles of electric travel will still reduce gasoline consumption and greenhouse gas emissions, but at a higher lifetime cost,''
It's nice to be vindicated, but I'm afraid the 40-mile standard automakers have bid each other up to is entrenched. And unfortunately, some recent news stories are predicting doom for the plug-in hybrid effort. While Toyota is still talking brave, I hope they take this Carnegie-Melon study very seriously.

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