Several of you have mentioned that pumped-storage hydroelectricity is a lot
like raising a big weight into the air. Yes, but much cheaper because the
water is essentially free. Actually, this is probably what gave the
official the idea of a similar system for an individual homeowner, but the
latter is impractical because of the mass involved, plus the heights to
which it would be raised are more limited.
Also, the point has been made that electric companies charge for energy,
not power. This is generally true for homeowners, but NOT for large
businesses, whose rates are a function not only of the kilowatthours used
but also the peak kilowatts during the month (or whatever period is
involved), sometimes just daytime peak. There are combination peak-power
and kilowatthour meters available for this purpose. The small peak-power
units use the same principle as a minimum-maximum thermometer to record the
peak power.
There are also meters that count kilowatthours for different periods of the
day, in places with peak/off-peak pricing. One utility in Iowa, for
example, offered (to cooperating homeowners) to measure kWh for
Monday-through-Friday 8 a.m. to 8 p.m. separately from kWh the rest of the
week, charging 125% the usual rate for the former and 50% of the usual rate
for the latter. I have a passive solar home with a considerable amount of
thermal mass, plus a natural-gas furnace as backup. One whole winter, just
to see if it was possible, I would turn the thermostat UP during the night
(to store excess heat for use on a cloudy day) and off during the 8 a.m. to
8 p.m. period, just to see if any problems would arise in doing no heating
during the peak hours (even though I didn't have electric backup heat). It
worked, and the three other family members never noticed or complained,
unaware of my experiment. (They are unaware of many others, like slowly
replacing incandescent bulbs with compact fluorescent bulbs.)
Laurent Hodges, Professor of Physics
12 Physics Hall, Iowa State University, Ames, IA 50011-3160
lhodges@iastate.edu http://www.public.iastate.edu/~lhodges