KING%KESTREL@sri-unix.UUCP (08/08/84)
From: Richard M. King <KING@KESTREL> I don't see why storage should be considered impractical, since it is already being done on a large scale. We could, for example, only use hydro at night or on cloudy days, doubling or more the amount you get from a given river. (Less power is used at night than during the day.) The fact that an electric car would usually never need to be recharged (A roof+hood area of 3-4 square meters gives about 2KW at noon; if the car has a duty cycle <10%, and most do, it would never taste an electric outlet!) might make them a winner finally. Solar shingles would be a real possibility. (Note that converting sunlight to electricity and using resistance heat is more efficient than most solar collectors, if you believe the 75-80% figure. Also, the efficiency of a thermal collector falls proportionally to the insolation (virtually nil on a cloudy day), and this wouldn't. An article in Technology Review of about 1 1/2 years ago gave about 3-4 cents/KWH as the cost of the home storage unit (Flywheel, Kevlar, ball bearings, permanent magnet motor/generator, evacuated) and approx 10 cents/ KWH for the collectors. (This is from memory; correct me if I'm wrong.) With the cells so cheap and efficient we can afford to provide enough to power our load on cloudy days! To summarize, the major uses of energy can adapt well to this source: ground transport electric cars with receiver roof domestic thermal (600 degree cast iron stores 20 KBTU/cu. ft; you need a 4 foot cube to heat a house for 48 hours) electrical (flywheels, batteries, whatever!) commercial easier than domestic; less happens at night heavy industry store the product! (Seriously, we would need twice as much (say) aluminum smelting capacity to meet America's need as we do now (assuming existing plants run at night - do they?) but the major cost of Aluminum is the electricity. These comments were jotted down very quickly - pardon any inaccuracies. -------
henry@utzoo.UUCP (Henry Spencer) (08/11/84)
> I don't see why storage should be considered impractical, since it > is already being done on a large scale. Not on anywhere near a large enough scale, and it's very difficult and expensive. We still have no really good and efficient way of storing electricity. > We could, for example, only use hydro at night or on cloudy days, > doubling or more the amount you get from a given river. (Less power is > used at night than during the day.) Hydro power (and its relative, pumped storage) is about the only bright spot in energy storage. But both are relatively expensive and, more important, applicable only in certain places. > The fact that an electric car would > usually never need to be recharged (A roof+hood area of 3-4 square meters > gives about 2KW at noon; if the car has a duty cycle <10%, and most do, it > would never taste an electric outlet!) might make them a winner finally. The problem with electric cars is not recharging, but battery capacity. The light-antenna scheme wouldn't do anything about this; what's needed is better battery technology, and it's being very slow in coming. > An article in Technology Review of about 1 1/2 years ago gave about > 3-4 cents/KWH as the cost of the home storage unit (Flywheel, Kevlar, ball > bearings, permanent magnet motor/generator, evacuated) and approx 10 cents/ > KWH for the collectors. (This is from memory; correct me if I'm wrong.) I can't comment on whether the numbers are right; the problem is that nobody has ever (to my knowledge) actually built such a thing. This is all speculation, not production equipment. > ground transport electric cars with receiver roof Only given much better batteries. > domestic thermal (600 degree cast iron stores 20 KBTU/cu. ft; > you need a 4 foot cube to heat a house for > 48 hours) Plus insulation, plus heat-exchange arrangements... Not trivial, and again this is not production hardware yet. > electrical (flywheels, batteries, whatever!) "Whatever" is definitely the word for it. Lots of ideas, but limited choice when one comes to viable, proven hardware. Despite years of effort, too. > commercial easier than domestic; less happens at night Don't forget that commercial buildings, and for that matter apartment buildings, have much less surface area for the amount of power they use than ordinary houses. This may be troublesome. > heavy industry store the product! (Seriously, we would need twice > as much (say) aluminum smelting capacity to > meet America's need as we do now (assuming > existing plants run at night - do they?) > but the major cost of Aluminum is the > electricity. I'm not sure... but I strongly suspect that a fair bit of the really heavy industry is running 24 hours/day already, to get maximum production out of very expensive capital investments. The major incremental cost of aluminum definitely is the power, but don't forget capital costs. I have no idea how they compare in the aluminum industry, but I know they are very important in some industries. I'm not trying to be a wet blanket -- the light-antenna notion will be a big thing, if it's practical -- but don't underestimate the problems involved in energy storage. At present the technology really isn't up to application on a national scale. Don't forget, also, that the energy storage system and/or the non-solar backup power sources *have* to be configured for the worst case, not the average case. Clouds may not hurt light antennas as badly as they hurt more ordinary solar power, but they'll still cut the output a lot, and at the worst possible time too (i.e. very cold weather). -- Henry Spencer @ U of Toronto Zoology {allegra,ihnp4,linus,decvax}!utzoo!henry