>Gillian R. Foulger, Ph.D.
>Is There a Free Lunch Out There? Geothermal Energy, its Potential
>and Challenges as a Renewable, Alternative Energy Resource
>As doom and gloom predictions from scientists about global warming
>rise to a crescendo, there is increasing public demand to know what can
>be done about it. Basically, there are two options – consume less, or find
>alternative energy sources to burning hydrocarbons, preferably renewable
>ones. Geothermal energy is one possible alternative. So how much of our
>energy consumption does it currently satisfy? What is its realistic potential,
>and what are the technical challenges to maximizing that potential? How
>green is it really, and is it truly renewable? Does it offer a free lunch, or
>are there environmental costs in utilizing it? Are your tax dollars at work
>on these problems?
>Gillian R. Foulger, a full professor of Geophysics at University of Durham,
>U.K., and director of her own geothermal consultancy company, will present
>some of the hottest geothermal issues, including an overview of how this
>fascinating resource is utilized around the world, what direction technology
>is moving in, and what is going on in the US. Gillian has worked with the
>U.S. Geological Survey for over 20 years on earthquake seismology, GPS
>surveying and geothermal energy. Her alter ego is leader of a global debate
>on whether volcanic “hot spots” are underlain by deep mantle plumes.

Dr. Foulger began her talk by explaining that she graduated as a geophysicist
back in the '70s. Her first work in the field was in Iceland, where she made
some remarkable discoveries of geothermal resources. Since then she has
been a leading expert in the field. She has since worked in England, Iceland
and the US, often in settings where brilliant grad students were part of the team.

Worldwide, one of the biggest users of geothermal resources are the Icelanders,
who get 40% of their energy from this source. Worldwide, there are about 9,000
Megawatts of electricity generated geothermally, with about 2,500 Megawatts
of that being generated in the USA. Of America's piece of the pie, 2,200 Megawatts
are generated in California. Most of California's power comes from The Geysers,
a geothermal area near Santa Rosa that is as unique, just as Hawaii is unique as
a volcanic area. Most of the rest of California's geothermal electric contribution
comes from Coso, a geothermal area in the Owens Valley.

The Geysers was a huge provider of geothermal power as recently as ten years
ago. When people started industrial scale power generating in the area in the
1960s there was only one big turbine running on the steam from a well.
That grew steadily to a peak in the late 1980s when the reservoir pressure
reduced to alarmingly low levels. The problem was that there were many small
producers, and each of them had an incentive to use more of the steam than
anybody else. Since then the Calpine Corporation has taken over management
of the whole area, and has got things under better control. Now about 1,200
Megawatts are generated, and the resource is expected to last for several
decades more, at which time much of the fluid will have been mined out of
the rocks.

Coso is the other big geothermal resource in California. It's the 7th largest
geothermal resource in the world, covering about 28 square kilometers.
It involves 177 wells, and is currently producing 300 Megawatts, supplying
electricity to about a million people. This one is being depleted at a much
slower rate than The Geysers. Dr. Foulger had good things to say about the
way the U.S. Navy is running this facility, which it owns. So far they have got
$4 billion worth of power out of it for a $1 billion investment and are managing
it wisely to maximize its potential.

Looking to the future, there are various possible ways to get geothermal
power out of the ground. One is to drill a deep well to mine heat directly of
the magma beneath volcanoes. Dr. Foulger "wouldn't bet her pension on
that one", but considers it an interesting idea in the Chinese sense. Another is
to put a coil under the ground in the yard, far enough below the surface that
the temperature is fairly constant. With a heat exchanger it is energy efficient
to get heat from there during the winter and sink heat there in the summer.
She said this kind of thing is becoming ever more common in Europe.

Tian Harter