Re: dams and electricity

[Rick Tarara <rtarara@SAINTMARYS.EDU>]

This basic concept--pumped storage--is one scheme that might be employed to
make solar or wind energy more practical.  For example, a solar array could
be built with say 250% of the power capacity needed to run a nearby city.  A
set of artificial reservoirs could be constructed nearby--one high, one low.
During the sunlight hours part of the solar output is used to power the city
and part to run pumps to raise the water from the lower to upper reservoirs.
At night, the water flows back down through generators to provide the
electrical energy needed.

While this is an expensive system, if political/economic/environmental
conditions dictate, it could become quite viable.  For example, if we ever
sign a greenhouse treaty, we would then find our use of fossil fuels frozen
or perhaps we would even need to reduce such use.  At that point, renewables
would have to be looked at not just as supplements but as main line
resources.  Some kind of storage system (Hydrogen production is another
scheme) would be necessary to compensate for the fact that neither wind nor
solar are 'energy on demand' resources.

In the situation described, however, such pumping would seem to serve only
environmental/recreational concerns and would be a net drain on the energy
delivery system.

Rick

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Richard W. Tarara
Professor of Physics
Saint Mary's College
Notre Dame, IN 46556
rtarara@saintmarys.edu

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----- Original Message -----
From: "Joseph Bellina" <jbellina@saintmarys.edu>

> This is a marvelous example of how economics plays a key role in most
> energy decisions.  You are absolutely correct, there is a net energy
> loss, but given the cost of capitol to construct a plant, it may be
> cheaper to build the pumps to run in the off peak periods, so that you
> can shave peak demand.  Whether to do it is a complex question, as has
> been pointed out.
>
> I really hate to think of the bean counters having the upper hand, but
> in this case they do.