From: Tom Gray <tgray@igc.apc.org>
Newsgroups: sci.environment
Date: 13 Oct 92 06:20 PDT
Subject: Re: --UCS Offers New Energy Policies
Nf-ID: #R:cdp:1466601783:cdp:1466601810:000:6183
Nf-From: cdp.UUCP!tgray    Oct 13 06:20:00 1992


<responding to Steinn Sigurdsson>

  SS1>Wind is never going to be more than 10% of capacity on US scale
  SS1>demands (ie some small countries may use it for greater fraction
  SS1>of capcity)

 TG1>But of course you cannot say this.  It's like saying nuclear
 TG1>reactors can never be made safe.

SS2>No, it is a quite different argument. I know the power available
SS2>in the airmass over the continental US and I know the current
SS2>power consumption of the US, I then estimated what fraction of
SS2>the land area could be dedicated to wind power and what the
SS2>turbulent mixing scale (vertical) is in the atmosphere.

Fine.  If you'll provide some numbers, I will
run them by Pacific Northwest Laboratory's experts.  PNL is the national
lab that released a study in 1991 stating that US wind potential totals
approximately 10.7 trillion kWh, using 13.5% of available land area.
(Note: Most of this land would continue to be available for agriculture,
grazing, or other uses.  The total amount actually occupied by wind
turbines would be much smaller.)  Have you seen this study?  If you
have specific criticisms, I'd like to see them.

SS2>        There is certainly enough power in the wind to provide all
SS2>of the US's needs, but only a small fraction can realistically be
SS2>tapped. The absolute limit is the point at which you start
SS2>directly affecting climate, the practical limit is well short of
SS2>that.

Yes, I don't think I am talking about either of these limits.  I
suspect a discrepancy in the numbers.

 TG1>A good, credible study of wind in the UK done a few years ago
 TG1>by Michael Grubb, who is now with the Royal Institute of
 TG1>International Affairs, found that approximately 1/3 of
 TG1>that country's electric power could be supplied by wind before
 TG1>penalties to the rest of the grid became unacceptably high.

SS2>If I remember the UK figure on lots of off-shore wind plant,
SS2>it is also relatively exposed and has reasonable wind potential.
SS2>Try the same calculation for Germany or northeastern US.

It's true that the UK's wind potential is greater per unit of land
area than that of the US.  However, the US still has many areas with
excellent wind potential.  I agree with you that wind's potential
in Germany and the northeastern US is limited, given currently
available storage and transmission technology.  I don't agree that
its potential for the entire US is limited to 10% of electric power
capacity, which is essentially your original statement.

 TG1>So we can take that as an approximate upper boundary, although

SS2>Grid variability is not the only factor. Also note that the UK
SS2>is pretty much a single grid, the US is much bigger and less well
SS2>tied in.

Certainly, but this is back to the "never say never" issue.  I don't
think it's reasonable to say that these technical limitations will
forever constrain wind energy's potential, any more than it is to say
that nuclear reactors can never be made safe.

 TG1>studies by Lockheed and General Electric in the late 70s both
 TG1>returned figures of ~1 trillion kWh annual potential for the US,
 TG1>which is a little more than 1/3.

SS2>grid capacity is 1TW, that's 9 trillion kWh/yr, so you're looking
SS2>at more like 10%, which is what I said...

Hmmm, that's interesting.  Total consumption has not yet exceeded
3 trillion kWh/year.  But at present, if you're willing to go along
with 1 trillion for wind, I'd be inclined to accept.  Hardly a trivial
power source.  At that level, it would be producing about four times
what nuclear is producing today.

 TG1>But these numbers still do not take into account enhanced
 TG1>energy efficiency or advanced energy storage systems.  To my
 TG1>knowledge, no one has even looked seriously at what could be
 TG1>done with EXISTING storage capabilities -- pumped, thermal,
 TG1>hydro or any other -- to maximize wind's potential.

SS2>Storage is pretty much irrelevant for 10% load, it would be relevant
SS2>for 1/3. Pumped hydro is mainly limited by site selection which
SS2>is currently limited mainly by ecological considerations and
SS2>cost. Thermal storage is a new technology, there have been some
SS2>impressive claims for it but I'm sketical until somebody
SS2>builds and operates one for a while.

Hmmm, I also left out compressed air energy storage (CAES), which is
getting very positive reviews from the Electric Power Research
Institute, based on a trial in Alabama.

I'm not sure how new thermal storage is, perhaps others here can
enlighten us.  I do know that Carbon Power & Light, of Saratoga, WY,
is using and promoting thermal storage as a method of reducing peak
demand loads.  The storage units (sized for individual buildings)
store power in a porcelain brick.  They take eight hours to charge 
and can then provide resistance heat for 16 hours.  I contacted Carbon 
and they seemed to think this was pretty familiar technology.

According to "Public Utilities Fortnightly" magazine, utilities are
also turning increasingly to battery energy storage systems (BESSs)
for demand-side management and backup power.  For example, the Puerto
Rico Electric Power Authority (PREPA) is currently building a $17
million, 21-MW BESS.

 TG1>Without investigating these possibilities, setting an arbitrary
 TG1>figure of 10% for wind's contribution is, as John McCarthy is
 TG1>so fond of saying, talking nonsense (even though 10 is a number).

SS2>Why do you assume that I did not consider the relevant factors?
SS2>If you can provide a number that contradicts my estimate I'll be
SS2>happy to reconsider and look at what I might have overlooked.

I assumed you did not consider the relevant factors because they were
not mentioned in your original statement, and because I felt your
original statement was in error.  I continue to hold that opinion.
A number which appears to me to contradict your estimate is provided
above.  Let's do pursue this and see if we can agree on the underlying
facts.

*******************************************************************
Tom Gray                                 EcoNet/PeaceNet: tgray@igc
Internet/Bitnet: tgray@igc.apc.org    UUCP: uunet!pyramid!cdp!tgray

Newsgroups: sci.environment