Mike Carrell wrote: > > JR: Yes, but much less fuel per passenger mile, and less CO2, because > electric cars are much more efficient that gasoline-only cars, or hybrids. > --------------------- > There are hidden assumptions in this assertion. I don't kow if they are > adequately analyzed.
I think they have been, by EPRI, NREL and others. There are some recent studies that conclude that advanced hybrid cars might be roughly as good as ordinary coal plants, but no ICE comes close to an advanced gas-turbine generator. And of course you don't get any less carbon emmissions than wind or nuclear power! > Well-designed electric drives are probably more efficient than ICEs during > acceleration, and can recover part of the kinetic energy during braking. > ICEs are not efficient under accleration. Typical driving involves lots of > acclerations. Yes. Especially in urban driving. > It is assumed that a utility plant, running under continuous load and > intelligent management, can burn fuel more efficiently than an accelerating > auto engine. So far, so good. But there are losses in transmission to the > user household, and in charging the battery -- as well as discharging it. All of these things have been taken into account. A good short intro is here: http://www.lenr-canr.org/acrobat/NRELenergyover.pdf It is dated, but good. Appendix C lists the studies it is based upon. > Q1 Where are reasoned estimate of the total carbon footprint of Los Angeles > with all eletric cars during a typical commuting day, including the carbon > emission of the utilities during the night charging cycle? EPRI has done a lot of projections in California, since that is where they are based. > Q2 Also: is it true that the electric utilities supplying Los Angeles could > support the charging load of all the cars for the next day's commute? Maybe not at at present. I think I have seen studies that they would need another nuke or two in California for this. It won't happen overnight, so there will be plenty of time to build new nukes or what-have-you. However the key thing to remember is that transportation actually consumes moderate amounts of energy. See the graph from Lawrence Livermore on the last page of the document above. Transportation consumes 5.3 quads of actual useful energy (and wastes a great deal more). That's out the total U.S. energy budet of 98 quads. That's including air transport, railways and so on. I think cars and trucks are at ~4 quads. Electric power converts to "vehicle propulsion" (the last stage) very efficiently, despite battery losses and so on. The electric power distribution system presently distributes 12.3 quads, so it would have to be built up somewhat to supply the ~4 quads needed for road transportation, but not by a huge factor. Mainly it would consume more fuel; it would probably not need much more equipment. Especially not with intelligent metering and remote turning and and off by the power company. Total energy consumed by transportation is 26.6 quads. Only 5.3 make it to "useful energy" ("vehicle propulsion" in this case) which is appalling innefficiency. As you see in the graph, other sectors are much more efficient. One of the advantages of recharging cars is that the customer doesn't care when you do it, as long as it gets done by morning. Most other uses of electric power have to be done in real time. They have be done in a fraction of a second after the demand is made. When the power company cuts your airconditioner, dims your lights, or stops drying your clothes, that's disruptive, but you wouldn't care whether it recharges the car at 1:00 am or 3:00 am. - Jed
