On Tue, Feb 27, 2007 at 10:31:18AM -0500, hendrik@topoi.pooq.com wrote: > > The hope is that large, well-engineered, monitored power plants can > produce energy in a cleaner way than small, internal-combustion engines. > Whether this is true is a matter of fact -- doesn anyone know the > relevant facts here? (Not to mention the energy losses in the > transmission of energy from the power plant to the wheels, of course) well, the current "consensus" is that yes, centralised power generation is easier to clean up. And each time you upgrade the generation source, all the electric cars on the road automatically get cleaner. That only makes sense. The transmission loss is significant (something in my head says 10% on average, but I don't know where that came from). The biggest issue is the infrastructure. Massive numbers of new power plants and significant increases in the transmission infrastructure. There was a recent "discussion" (very reminiscent of this one) on slashdot where some folks ran the numbers on an electric car battery that could recharge in a few minutes. That's great until you realise that you have to dump a couple (?) hundred kwh into the thing in just a few minutes. That works out to a couple thousand kwh capacity per plugin apparatus. Put several of those into a "recharging station" and you're looking at some serious electrical infrastructure. Being able to serve up say 8 cars at a time with a 5 minutes of recharge and a 150 kwh capacity battery rig per car means you need 14,400 kwh capacity in that station. Don't know how accurate my numbers are but I think it adequately illustrates the problem. A typical house in the US has 200kw service, so you'd need the power service of 72 houses to put up 1 recharging station. Other option include "swapping" batteries at the station. That's all fine as it means you get in and out of the station in just a few minutes with a conventional battery rig. but still, you have the same charging problem -- in order to serve 8 cars every 5 minutes or so, you are still moving the same amount of power out of the station, but now you also have to store all those batteries while they go through their 6 hours recharge. Obviously that kind of change can't happen overnight. Its an ugly problem, no matter how you cut it. A
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