Geothermal Energy and Earthquakes

Geothermal Energy is one of those sources that is, within normal scales, sustainable, and it is currently being drawn upon, so that relative costs and techniques don’t have to be invented for it to become a viable program. It can, however, be considered to be useful at two different levels, there is the small-scale facility, often referred to as ground source heat pumps and then there are the full-scale power plant types of operation.

We had considered putting a ground-source system into our own home, and I wrote about that, and other family reviews of the technology back in my Oil Drum days. Arising out of that discussion, and comments, it appears that the current cost of systems remain up around the $20,000 to $30,000 dollar mark, which is considerably too expensive for folks such as myself, relative to the energy and cost return that we would achieve from such an investment. However the comments on that article are informative and well worth a visit.
Ground source heat systems (Source)

It is the larger scale operations that I want to write about today. It is a system that is growing, but in the process is stirring more public controversy. Here much larger and longer pipes are drilled down into rock that is much hotter than normal, and the resulting steam/hot water is extracted back out of the ground and used both to generate electricity and for district heating. These are the systems, such as can be found at The Geysers in California, where Calpine runs 15 power plants that generate some 725 megawatts of electricity.

The Geysers meets the typical power needs of Sonoma, Lake, and Mendocino counties, as well a portion of the power needs of Marin and Napa counties. In fact, The Geysers satisfies nearly 60 percent of the average electricity demand in the North Coast region from the Golden Gate Bridge to the Oregon border. The Geysers is one of the most reliable energy sources in California delivering extremely high availability and on-line performance and accounts for one-fourth of the green power produced in California.

There are, however, different ways in which the heat can be extracted from the ground, depending on the nature of the rock which is being used as a reservoir. In the first, and simplest case the rock is already fractured and contains water, under pressure, that can be tapped by the wells that reach down into the rock. The water is refreshed, either from the surrounding volumes, or by reinjection of the spent fluids from the power plant, after the heat energy has been extracted.

How the Geysers get power

Such a system is, for example, being developed in Switzerland. But whenever fluids move and are injected, or removed from highly-pressurized systems then problems, such as earthquakes can result, and this is what generates the considerable public concern particularly when such earthquakes happen in areas that are already prone to earthquakes.

But this is part of the problem, in that the places where the hot rock comes closest to the surface lie along the boundaries of the plates that comprise the shell of the Earth. And these places already see earthquakes – whether in Japan, Iceland or Switzerland. So if one is going to drill into this rock, and then crack the rock between two wells, to provide a path for fluid to flow and gain heat, then you will affect the rock structure to the point that the change in stresses around the operation can trigger small earthquakes.
LASL plans for fracturing between wells to extract heat from geothermal wells

As the fractures grow to generate networks this weakens the rock, and the fluid lubricates the planes along which the rock can slip, so that rock which was already approaching the stress levels at which the rock would move and generate an earthquake now can, and so it does.
Concept for geothermal heating in Switzerland where they plan on using natural rock fractures

Now in almost all cases the stresses would have continued to build until an earthquake finally occurred. And at that point the energy released by the quake would be greater than that released by the geothermal operation (since the stress levels would be higher at that time, and the failure would be more violent). But it is hard to get that concept over to the public.

Basically they see that the geothermal well was drilled, and an earthquake resulted. That it ameliorated a worsening potential earthquake is something that is not easily recognized, especially since the smaller quake can still cause damage (as it has done).

The problem, and the public relations aspect is a significant part of this, is something that needs to be addressed forthwith, since at the moment the Department of Energy is gearing up for a significant investment in geothermal power including new Enhanced Geothermal Systems (EGS).

Before EGS could be implemented, scientists would need to calm concerns about insufficient technology and the possibility of earthquakes at EGS sites. The allotted $30 million would also have to increase in later years to reach the $1 billion the panel report calls for overall. Still, many scientists view the project as our best baseline energy option.

“We’re no longer limited by just discovering the Icelands of the world,” says Jefferson Tester, a professor of chemical engineering at MIT who chaired the EGS panel. The report estimates that by 2050, EGS could be implemented to a capacity of 100,000 new megawatts of power – more electricity capacity than all of the nuclear power plants in the United States combined.

At present the problem that relates earthquakes and geothermal energy extraction is known, and recognized

a major quake requires a several-kilometer-long fault, argues Ernest Majer, a seismologist at the Lawrence Berkeley National Laboratory. Engineers know not to put EGS sites near large or dangerous faults, and the small cracks created by the system itself are not dangerous. “We can’t make faults as big as Mother Nature does … and there has never been a damaging geothermal earthquake anywhere in the world,” he adds.

At Geysers in California, there are about 3,000 earthquakes per month, according to Majer. The largest, however, reached only 4.6 magnitude – big enough to be noticeable, but not dangerous.

Majer is enthusiastic about how education and community involvement can help to allay earthquake fears. The quakes at EGS plants can be controlled and monitored for safety, and better research will help scientists and engineers understand how to make EGS plants even safer, he says.

Explaining the issues to the public may, however, be another story.
(For the record I am working with Dr Majer on a program that could be funded under the EGS program).

P42. Pick Points

Half-a-dozen or so stories of interest:

Back in March Switzerland signed a deal with Iran for a 25-year supply of natural gas it appears that this will bring a fourth gas corridor though Turkey, that will provide an additional connection to Europe, and it remains under criticism. Iran sees it as the start of a new relationship with Europe, and a possible model for others. The gas will come from Assalouyeh and require a new pipeline that will be built by the Turks. Germany has taken the hint, and Gerhard Schroeder is now in Tehran to see what sort of a deal they can cut. The pipeline will also provide a pathway for Turkmenistan gas to get into Europe without going through Russia. Iran, meanwhile still considers the discussions ongoing with Bahrein, even though the latter cut them off when some Iranians claimed the kingdom belonged to them. Iran is discounting those statements.

Russia, meanwhile has apparently not been sending the agreed amount of natural gas to Poland. So far it has only got 75% of the agreed amount, and now Gazprom wants a new deal. The Council on Foreign Relations has just released a special report on Eurasian Energy Security that calls, among other things for a better network of interconnections and integrating Russia more into the energy picture in Western Europe. It also calls for a common regulatory framework. Rune’s work on whether the UK will get through the winter without problems, suggests it will be close.

Iceland is looking to exploit its Geothermal power in the face of major financial problems. Of the three natural resources the country has, fish, hydro and geothermal, the first two are in some trouble, and with an increasing amount of geothermal due to come on line in the next few years all they need are investors. For those in the US looking at using geothermal, the more likely domestic source will be ground-source heat pumps, and the cap of $2,000 for a tax credit which would otherwise be 30% of the cost, has been removed. In an earlier post at TOD I heard that the going price was in the $20,000 to $30,000 range, and so this is a significant change (but not enough to justify my doing it yet).

The numbers for oil production from Mexico, of which I have written in an earlier post, are growing worse quite quickly. Country production fell 9.2% in January , with Cantarell now down to 772,000 bd. Pemex claim they can keep it to an average of 700,000 bd this year, but this may be doubtful, and will hurt exports. That did not help oil and gas futures (the latter at $4 per million btu). There is a new documentary on the oil situation now out called Blind Spot which has got a favorable review at TOD but since they were out of copies when I tried to order one, it will be a wee while before I can do a review.

Last week China was tying up loans with Russia to ensure long-term delivery, and then with Brazil. This week it is Australia’s turn with Exxon Mobil signing a long term agreement for LNG from the Gorgon project that will send 2 million tons a year of gas north for 20-25 years. Projections for the LNG plants being put into Gladstone in Australia have slipped from 2011 to 2012 for the first LNG plant, which will liquefy coalbed methane, and the customer has not been defined. (Though as I noted last week I wouldn’t be surprised if they had a South Asian accent).

The current low prices for energy, taken with flooding from the fire-fighting last year, means that the historic Barentsburg coal mine in Norway may not reopen.

More stories can be found at The Energy Bulletin and Drumbeat at The Oil Drum.