Hot rocks rockin'

Geothermal power: a core climate solution

Posted by Joseph Romm (Guest Contributor) at 1:06 PM on 24 May 2008

Read more about: geothermal power | energy | investing | renewable energy

While wind and solar get the media attention of a sexy starlet, good old geothermal power is treated like an aging character actor.

But geothermal energy is, in fact, sizzling hot these days. Big-time investors from Warren Buffet to Goldman Sachs to Morgan Stanley to Google have begun investing:

In 2007, private equity firms invested more than $400 million in geothermal energy, which is derived from hot water under the Earth's surface and can be used for space heating or generating electricity.

Why the interest in a form of energy that President Bush repeatedly tried to zero out of the Department of Energy Budget? One reason is the soaring cost of conventional power like coal and nuclear. Another is the growing awareness of just how much is zero-carbon electricity will need in coming decades.

But perhaps most important for this reemerging technology, in the 2005 energy bill, Congress finally extended the renewable energy tax credit to geothermal "which at 2 cents per kilowatt hour for the first ten years, can account for a third of the cost of a project" -- and which will expire in December unless Congress gets its act together (see here)!

The U.S. currently has 3 gigaWatts (3000 megaWatts) of geothermal, one third of the world's capacity, generating $1.8 billion electricity sales. What is the ultimate potential?

The US Geological Survey estimates the US could generate 150,000 megawatts.

A major 2007 study by MIT on Enhanced Geothermal Systems (EGS) found that it could be a provider of substantial baseload (24/7) power:

The panel thinks that with a combined public/private investment of about $800 million to $1 billion over a 15-year period, EGS technology could be deployed commercially on a timescale that would produce more than 100,000 MWe or 100 GWe of new capacity by 2050. This amount is approximately equivalent to the total R&D investment made in the past 30 years to EGS internationally, which is still less than the cost of a single, new-generation, clean-coal power plant.

Technology Review has a nice summary piece here. And you can find a lot more about geothermal here.

So add this to the list of commercial technologies that can deliver large quantities of low carbon power by mid-century. Could it be one of the 14 or so wedges we need to stabilize below 450 ppm (see here)? That seems a stretch at this point. But it could certainly be a big piece of a wedge, and that alone means it merits serious attention.

This post was created for ClimateProgress.org, a project of the Center for American Progress Action Fund.

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16 Comments | Post a Comment

EGS is different from conventional geothermal

Conventional Geothermal is represented by that map.
EGS on the other hand works practically anywhere.

The main difference being:

Conventional geothermal is 1 mile deep, and the water is already there.
EGS is 3-6 miles deep, and the water has to be pumped down. (Often from waste-water treatment plants)

The major advantage of geothermal is that it works 24/7, with a yearly capacity equal that of Nuclear power.

As for that 3GW, nearly all of it is located in California. Nevada though, as far as conventional geothermal goes, looks pretty damned hot.

-David Ahlport

by GreyFlcn at 6:47 PM on 24 May 2008

Why not include geothermal heat exchangers?

Three miles? What about six feet?

by Colin Wright at 9:03 PM on 24 May 2008

Yeah

Geo heat exchange has the potential to eliminate 36% of GHG and doesn't use water. That 36% far surpasses geothermal's potential and at a lot lower cost. plus it directly replace fuel oil and natural gas.

Geothermal uses way too much water, is too expensive, and causes earthquakes. It is just not needed.

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin

by amazingdrx at 9:24 PM on 24 May 2008

Better not to confuse things

Ground source heat pumps are not geothermal in the same sense geothermal electricity is. Just below the frost line ground temperature is somewhere between 45 and 70 degrees F. The milder temperature lets a heat pump extract heat or cold from such sources more efficiently than it can from air.

Another reason not to confuse things is that sometimes true geothermal sources are used for space and hot water heating.

by Gar Lipow at 10:41 PM on 24 May 2008

EGS

Hmm, didn't France build a demo plant?

by Gar Lipow at 10:43 PM on 24 May 2008

re: DrX

Geothermal uses way too much water,

Depends if you use a condenser or not.
EGS so far uses condensers.
http://greyfalcon.net/nuclearwater.png
Also air cooling can go a long way as well.
http://www.nrel.gov/csp/troughnet/pdfs/2007/dersch_dry_co ...
Conventional geothermal, they just drain the water that was already underground by flashing into steam. It doesn't consume surface water.

is too expensive,

Relative to what?
It's actually quite affordable compared to other new builds on a cents per kWh basis. Geothermal makes up nearly all of the non-hydro renewable generating capacity in California.
http://greyfalcon.net/geothermal
Especially when compared to the full costs of CCS/Nuclear.

and causes earthquakes.

So far thats anecdotal.
"Basel experiences dozens of tremors every year, 3 or 4 of which may hit the 3.4 magnitude similar to the supposed Geopower triggered quake."
http://www.treehugger.com/files/2007/01/geothermal_powe.p ...
And even if it is true, it then comes down to comparing relative risks to other power generation sources. And of course citing and mitigating for those risks.

It is just not needed.

Well we certainly need something to provide/replace a hell of a lot of power. It can't all be efficiency gains, and conservation. If it comes down to EGS versus Nuclear, I'd pick EGS.

-David Ahlport

by GreyFlcn at 11:42 PM on 24 May 2008

Links

Here's a video including a condenser:
http://www.calenergy.com/html/aboutus4.asp

And here's a point from an article on this that I like:

Jefferson Tester: The EGS figure for the whole world is on the order of 100 million exojoules per year. We now use worldwide just over 400 exojoules per year. So you do the math, and you know you've got a very big source of energy.
http://www.technologyreview.com/read_article.aspx?id=1723 ...

-David Ahlport

by GreyFlcn at 11:59 PM on 24 May 2008

What sort of conversion efficiency?

"Air cooling can go a long way" implies the fraction of mined heat that cannot be converted to work is small. In fact it must be large both in absolute terms and in comparison to engines running on higher-grade heat.

--- G.R.L. Cowan, H2 energy fan 'til ~1996

by GRLCowan at 6:01 AM on 25 May 2008

False dilemna

But it isn't a choice between nukes, coal, oil and geothermal. Wind, solar, water, and biogas power is enough, along with conservation.

Use systems that reduce water use and the cost goes way up, with heat exchangers and condensors and pumps. The same with deeper drilling, too costly. Too costly compared to what? You might ask.

Compared to renewables and conservation. Conservation is the cost per unit winner, wind is second.

Why risk the earthquakes, when this source is not necessary? Injecting water into hot rocks makes them slippery. Many of the best geothermal source areas coincide with earthquake prone areas. The magma proximity to the surface seems to be the coincidence.

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin

by amazingdrx at 6:26 AM on 25 May 2008

I wish I could believe

lot of NIMBY issues with conventional geothermal, and the track record for predicting flow of water across the rock formations is not too good

the 3 mile stuff sounds intriguing, but no one knows how to do it (as far as I know)

I love the 6 foot heat exchanger stuff (more in the efficiency category?) and think it needs to be promoted

anyone have any good ideas on what is needed to promote the heat exchanger stuff?

by ce1907 at 6:32 AM on 25 May 2008

Show me

Show me a geothermal plant that is cost competitive with wind, doesn't use water, and can operate for 30 years, like wind can, with no earthquake risk.

Then maybe capital would be better spent on geothermal. Until then wind should get the money. Messing with geologic forces is just not a human scale project. It's like humans messing with nuclear forces.

With the human penchant for corruption and short life span, these are areas better left to nature. Research is ok, but mass production scale assault for bottomline profit? not a good idea. Even oil and coal have proven too dangerous for human levels of competence.

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin

by amazingdrx at 6:37 AM on 25 May 2008

Well ce

The local news here had a story on it, installed by a local contractor. They said it can save thousands per year in haeting/cooling costs.

The process of burying the ground heat collecting plastic tubing and installing the "furnace" was featured.

How to get politicians to vote for subsidies for it? I wish my congressman would emphasize stuff like this and solar and farm biogas, it's all happening right here in our district.

Make a few ads visiting with people who are using these technologies and talk about how congress could divert subsidies for fossil and nuclear industries to boost these renewable and conservation systems. That would make the environment a campaign issue again.

But not many running for office want to go this route it seems. Media will have to promote it first. At least the local news tried here. Rising energy costs are a big issue here, with heating a serious, mortgage breaking burden for homeowners and small business.

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin

by amazingdrx at 6:47 AM on 25 May 2008

Ground Source Heat Pumps

If you want to know more about this important technology including a list of accredited installers in your state check out the website of the International Ground Source Heat Pump Association:

http://www.igshpa.okstate.edu/index.htm

As Gar stated above, GSHP is very different from the hot-rocks geothermal systems which are the subject of the OP. It is essentially a local, building-by-building conservation technology (using less energy to produce a given heating or cooling result) rather than an energy source technology. Like Gar, I believe it would be less confusing if we were to avoid the term geothermal when describing GHSP (even though the IGSHPA itself does so).

The true meaning of life is to plant trees, under whose shade you do not expect to sit.

by spaceshaper at 11:48 AM on 25 May 2008

Hot rock energy is not "renewable"

The average heat flux flowing from the core to the surface is only 0.045 W/m2. Deep rock is only hot because it is well insulated by the earth above it.

Once water is pumped into a deep hot rock formation and the heat is "mined", the resource is depleted and will take a very very long time to reheat from the tiny trickle of heat coming from the core.

A deep geothermal power station requires several cubic miles of deep rock to be fractured to allow increased water permeation and steam flow. A hot formation of several cubic miles will cool to the point where it no longer generation steam of sufficient pressure to run turbines after 5-10 years. The power station then need to be move to a new formation.

I'm not convinced that fracturing and cooling HUGE volumes (several cubic miles per small power station depleted in 5-10 years) deep rock is going to be a sustainable activity. There are so many unforseen dangers, earthquakes, subsidence (even a few inches could destroy a whole city?), draining of aquifers & lakes, etc etc.

Compare the geothermal average heat flux of 0.045 W/m2 to the average global solar flux of 340 W/m2.
One could say "does not compute".

The reason deep geothermal is not providing us with Terawatts of cheap clean electricity is that it really can't. Even if it does manage to provide some significant proporation of our energy requirements for a short time - it is "heat mining" and once mined it is gone, at least on a time scale that is meaningful to us.

by elbarto at 4:43 PM on 25 May 2008

Well stated

Hadn't thought of the heat flux angle. Very effective counter argument.

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin

by amazingdrx at 8:47 PM on 25 May 2008

Geothermal is about to take off in Australia

There is a rush of exploration for deep hot rock Geothermal in Australia at the moment, with 32 companies having applied for geothermal licence areas across the continent. In the state of South Australia alone, 22 companies have applied for 205 geothermal exploration licences.

The most advanced company is Geodynamics, which is busily drilling away in the Cooper Basin on the edge of the Simpson Desert in the eastern outback.

Their first production well was drilled to its target depth of 4,221 m (13,850 ft) in January, this year, at which depth the temperature was found to be 280degC. Their second well is close to complete. They plan to have their first pilot 1MW power plant running later in 2008, and their first commercial 50MW power plant unit will go online in 2012. Their power plant will function by re-injected water will back into the ground in a closed loop. They claim to have a resource of 400,000 petajoules of high-grade thermal energy at their disposal so far.

The cost of this electricity will be significantly less than the projected cost of 'clean' coal or nuclear. It seems that the only impediment to progress is getting the investment required to allow the purchase of more rigs, and the construction of the necessary power lines and power plants.

by picoallen at 8:27 AM on 26 May 2008

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