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Miscellaneous / Climate Change


Subject:  Re: Electric car monies Date:  2/5/2013  2:14 PM
Author:  mschmit Number:  40654 of 90637

Power plants run at or near their peak efficiency all the time. Internal combustion engines do not. A large percentage of miles traveled is while cars are still warming up and at half or less of their nominal efficiency (which is generally 20-25%). The best gas cars get to about 35% efficiency...after they are warmed up.

The lowest hanging fruit for reducing gas consumption on transportation is for short trips with an EV. Short is on the order of 2-5 miles or so. An EV (or PHEV) gets to maximum efficiency almost immediately.

In my Prius plugin I use about 200 watt-hours per mile on short trips. But if I use gas it is getting about 25-30 mpg (not warm yet). So for 5 miles this is 3412 BTUs (plus 10% for charging losses). For gas this is 23000 BTUs. On a longer trips at freeway speeds it is more like 4700 BTU (per 5 miles) compared to 12000 for gas.

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