From: tgray@igc.org (Tom Gray)
Newsgroups: sci.energy
Subject: Re: Wind power
Date: 7 Apr 92 16:22:00 GMT
Article-I.D.: igc.1466300054
Nf-ID: #R:92070.205608BN9QC@cunyvm.bitnet:-1381637405:cdp:1466300054:000:9776
Nf-From: cdp.UUCP!tgray    Apr  7 09:22:00 1992


From: Tom Gray <tgray>
Subject: Wind power

/* Written  9:22 am  Apr  7, 1992 by tgray in cdp:wind.energy */
/* ---------- "Wind power" ---------- */
Ilana Stempel writes:

>>>Just writing a quick note to see what you folks out there think
about wind energy for the future.  Please post some type of
response, either here or to my mailbox.

Wind energy is a very promising source of electric power for the
future.  The U.S. and world resources are on the same order of
magnitude as hydropower resources, but wind is less restricted to
specific sites and its environmental impacts are less than those
of hydro and far less than those of fossil fuels.

Rolf Meier writes:

>>>Wind energy is an excellent choice for rural dwellers who have
the necessary wide open spaces, and who would benefit from the
independence that their own power source provides.  If they have
excess, the power could be sold to the utility.

In general, I agree.  However, it needs to be made clear that most
homeowners are going to want to remain connected to the utility
grid for backup power when the wind is not blowing -- adding
battery storage significantly increases the cost of wind power.

Also, it should be made clear that the price a homeowner will
receive from the utility for excess power varies dramatically
depending on state law, the type of utility involved (rural
electric co-op, municipal utility, etc.) and how difficult the
utility wants to be.  This is something that bears looking into
before making this decision.

>>>Wind energy is not viable as anything more than a supplement to
the primary source of electricity (eg nuclear).  That is because
it is essentially unreliable.  If energy storage problems could be
solved, then the importance of supplementary sources of energy
would be more signigicant.

This is not exactly correct, although no one can argue with the
last sentence.  While wind energy may be only a "supplement" as
Rolf defines that word, it could probably supply, for instance,
the amount of power that nuclear power provides in the U.S. today
without major changes in the utility system being required.

There is a fairly detailed study of the U.K.'s utility grid
available which concluded that approximately 30% of that country's
electric power could be supplied by wind before its value was
significantly reduced by the increased cost of adjusting thermal
power plants to compensate for changes in the wind.

Gary Coffman writes:

>>>While I'm not too optomistic about wide scale windpower,
unreliability is not a limitation as long as a grid exists. The
wind is always blowing *somewhere*. You just can't count on your
own personal windmill making power when you need it. As part of a
continent-wide grid, however, wind power can be very constant and
reliable.

Yes, that is correct, over a broad geographical area the
likelihood of wind power being available at a given point in time
is increased.  However, people should also be aware that a nuclear
power plant, on average, is available to generate power only about
65% of the time.  The rest of the time it is off line for service
or even for occasional unscheduled outages, and the power system
must maintain the capability to fill in when it is down.  The
problem of "filling in" for wind is different, but not
dramatically so.

People should also know that wind patterns can be highly
predictable, depending on location, and that they can match up
well with utility load (demand) patterns.  For example, a 1989
study by Pacific Gas & Electric Co. concluded, in part:

"The fit of the wind to PG&E hourly loads has been evaluated for
recent years at both Altamont [Pass] and the Solano County site of
the MOD-2 [an experimental large wind turbine].  The Solano winds
have an excellent fit to PG&E loads, and would give a wind turbine
a capacity value of 75-80% of its rating, a fit nearly as good as
conventional peaking power plants, such as gas turbines . . . "

Similarly, a brochure entitled "Cost of Wind Energy" from the
Utility Wind Interest Group (sponsored by the Electric Power
Research Institute and the National Renewable Energy Laboratory)
says in part:

"One utility . . . [PG&E] has sufficient experience with wind to
be able to forecast annual energy production on a monthly basis."

Jerry Miller writes:

>>>But, has any data been accumulated on the global effects of a
global dependency on wind power?  <balance of posting omitted>

Not a whole lot, to my knowledge.  But what effects are you
talking about here?  If you are talking about the effect on
electric power systems, that is addressed above.  If you are
talking about environmental effects, those are likely to be
minimal for the foreseeable future.  But feel free to ask about
specifics.

Gary Coffman writes:

>>>There have been studies, one summary was posted here recently.
Wind energy is very location dependent, and is somewhat seasonal,
but there is a lot of it to be tapped. I don't *think* that it
would be economic to attempt to tap 1.2 Terawatt hours of wind on
a daily basis, so it probably won't ever supply total US base
load. Still it can make a contribution nearly as large as hydro at
about the same cost as duplicating hydro at today's construction
costs though we certainly aren't going to do *that*.

This all sounds right, although I think wind's potential to supply
power to the U.S. grid is somewhat larger than hydro's.  A 20%
contribution by the year 2020 seems to me like an ambitious, but
achievable, goal for wind electric power.

A useful source for this kind of information is "An Assessment of
the Available Windy Land Area and Wind Energy Potential in the
Contiguous United States", PNL-7789, published in August 1991 by
Pacific Northwest Laboratory.  It finds, for example, that the
wind energy potential of the state of North Dakota alone is equal
to 45% of total U.S. electric power demand for the year 1990.

Jerry Miller writes:

>>>Do you think we have the transmission technology to feed the
grid effectively with variable, decentralized sources?

>>>Do we need to engineer new methods of step-up, step down
transforming, and current quality control, etc, etc, or can we
make this type of decentralized grid transmission fully workable
with off the shelf technology?

>>>Powering the grid effectively, and profitably, with
decentralized sources-- this is something I'd like to research and
discuss...

To my knowledge, this is not a serious problem.  The windfarms in
California today are operating with what is essentially
conventional substation and interconnection technology.

Power quality is a potential issue, but I believe it will soon be
solved by variable-speed constant-generation technology (there are
already commercial variable-speed machines entering the market).

Availability of transmission lines is a more serious constraint on
wind technology -- I think -- and is an issue that really needs
some comprehensive study.  Many of the windiest areas in the U.S.
are served by inadequate or no transmission capacity, and new or
larger lines would probably have to be built.  But without a
study, it's hard to say just how big a problem this is.

Gary Coffman writes:

(Jerry Miller's question) >>>>Do you think we have the
transmission technology to feed the grid >effectively with
variable, decentralized sources?

>>>We know *how*, I'm not sure we can afford to implement the
solutions.

If we can afford acid rain, mercury contamination and global
warming, we can afford wind power.

Simplistic, to be sure, but the central point is that once
environmental costs are properly accounted for in electricity
pricing, wind energy is going to stop looking so expensive, even
with increased transmission capacity.

>>>We need to sharply reduce long distance transmission losses via
high voltage DC trunks, preferrably superconducting. We need to
install decentralized synchronous inverter systems. We need to
install decentralized control systems. The list is fairly long,
and not cheap, of what must change. We know how, theoretically,
but practical implementation would be a horrendous job. Some of it
will be done in any event to more efficiently utilize current
central plants, but not soon.  The direct payback is too long and
doesn't come under any one state PSC so it's difficult to build
into the rate base.

I'll bow to your expertise here, Gary, although I believe that
quite a lot could be done -- that is not now *being* done -- to
determine how best to reduce these costs in the near term.  We all
have to talk in pretty general terms here because nobody, to my
knowledge, has really looked at these issues in a serious way.
How much storage, for example, is available at existing hydro
sites?  Nobody knows, because nobody's ever bothered to try to
find out.  How little new transmission capacity do we need to
install 50 GW of wind?  Same answer.  I think these are important
questions.

>>>>We're partially there today. Almost all the regional grids are
tied together already. Shipping power long distances is still
expensive though. Today it's still cheaper to ship fuel than to
ship electricity when the distance goes over about a 100 miles, or
when the quanity of energy to be delivered is high. We do it in
some cases for non-economic reasons, but it costs us. That has to
be reversed before decentralized power becomes a reality.

Again, incorporation of environmental costs will help.  Also,
there are significant amounts of wind power available, for
example, in the Northeastern U.S. at sites that are not so far
from existing lines.  How much?  "Nobody knows."  New York's
utilities are studying possible sites for wind right now to try to
find out more about this, but to my knowledge, that's the only
state where this kind of work is being done.
Newsgroups: sci.energy