From: ccw@prefect.uucp (26554-wood)
Subject: Re: Hydro energy storage systems
Organization: Bellcore, Livingston, NJ
Date: Thu, 27 Aug 92 14:29:39 GMT

In article <1992Aug27.063914.4425@bb1t.monsanto.com>
bjgaed@bb1t.monsanto.com writes:

>In article <pjh.714824425@nessi>, pjh@eng.cam.ac.uk (Philippa Hogben) writes:

>> The point, in this case, is not whether you can actually whether you
>> can get back exactly the same amount of energy as you put in. The idea
>> of pumped storage systems is to keep the "base load" power stations
>> running at their optimum output during the slack period and to provide
>> a supply for the peaks without the cost of building extra coal, gas or
>> nuclear power stations.

>> Philippa

>And more to the point, is this a good idea?  Obviously it's a good 
>idea for the power companies.  They get to sell more electricity 
>without more investment in capacity.  While this is clearly an 
>economic advantage, I don't think it is advantageous from the 
>standpoint of overall efficiency, conservation of resources, 
>environmental impact, etc.

Where do you think the power companies get the money to invest in
capacity?  The money ultimatly comes from the consumers.

>Now, I'm only guessing at these numbers, but if the thermal efficiency 
>of the original generating system is 35%, and the in-out efficiency of 
>the pumped storage system is 60%, as someone suggested, and we lose 
>10% of the electricity each direction from transmission losses, we 
>have an overall efficiency of .35 * .90 * .60 * .90 = 17% of the 
>energy finally reaching the consumer.  

Fallacy number 1: The energy reaching customers is 17% of what?  The
proper comparison is to the fraction of fuel energy reaching customers
directly, which is .35 * .9, or 31%.  So the net loss is really only
your estimated efficinecy of the storage system.

>Or should we junk the idea of large-scale energy storage entirely as 
>just too inefficient?

Define efficiency.  My definition is meeting consumer's demand at the
lowest cost (which also includes the cost of pollution control
equipment, or purchasing "smog rights").

>My original point was that these projects are possibly the right idea 
>but at the wrong time.  Conservation and efficiency are a better 
>investment right now for an industrial society like the U.S., IMO.  It 
>may not be the best investment for a utility company, but here again 
>we make a mistake if we treat a utility company as a closed system.

The problem is that lots of different individuals make the investment
decisions.  Unless you are advocating a centrally-planned economy, the
utility companies can not count on conservation and efficiency when
their generating capacity is maxed out, and demand is threatening to
cause brown-outs.  Expanding capacity to meet demand at the least
possible cost is the job of the utilities.  If the utility rates
reflect the true cost of expanding capacity, the free market will
encourage users of electricity to conserve and become more efficient.

>It is an open system with fuel and capital inputs from the larger 
>society and waste outputs.  Our vision of the future seems to depend 
>on just how much entropy the planet can absorb.

Entropy is the least of our worries.  CO2, chlorofluorocarbons, SOx,
NOx, heavy metals, and so on are the real concern...

>--Electric Monk            (Bruce Gaede); 
>                            e-mail: bjgaed@ccmail.monsanto.com

Chris


Chris Wood     Bellcore     ...!bellcore!prefect!ccw
                         or ccw@prefect.cc.bellcore.com

Newsgroups: rec.arts.sf.science