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Friday, July 15, 2011

THE FUTURE OF GEOTHERMAL ENERGY

FIRST:



Oh, oh, Super Typhoon Ma-On is now a Category 4 at 130 MPH and is projected to make landfall on Honshu as a Category 3 (111-130 MPH) storm on Tuesday, possibly sweeping across Tokyo.  Fukushima is now in some jeopardy.  While this could easily change, the current potential for significant damage is ominous.  


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My first renewables project was as a reservoir engineer for the Hawaii Geothermal Project in 1972.  We drilled a well to a depth of 6,140 feet ( a mile is 5280 feet) in 1976 (HGP Progress Report) and began producing 3 MW of electricity beginning in 1982.  Our well at that time was the hottest in the world at 675 degrees F.  It turns out that in the 1990's, a driller near our well, at 8,100 feet, struck magma at 2000 degrees F.

This is what Puna, Hawaii looks like today at the Puna Geothermal Venture operations, which in April was producing 35 MW:

One comparison with oil is that a Saudi Arabian petroleum well produces the equivalent of 500 MW of oil per well.  A geothermal well is about the same diameter and only is good for around 3 MW.   Another interesting rule of thumb is that the hot liquid water expands by a factor of 1500 upon lowered pressure and conversion to steam.

How does this resource work?  Rainwater percolates down and magma heat conducts heat up.  The result is a reservoir of hot water and steam that is brought to the surface to spin a turbine to produce electricity.  Ninety percent of world electricity passes through this steam turning turbine spinning generator process.

The U.S. has a geo-megawatt capacity of about 3,000 (Hawaii alone has a peak electrical production close to this figure), with the Philippines at 1,840 and Indonesia at 1,000.  In the U.S., geothermal only accounts for 0.4% of electricity produced, and the tables on the right show that on an overall world energy usage basis, geothermal is but 0.06% of the supply.  However, the Indonesian government plans to spend $30 billion by 2025 to add almost 10,000 MW.

There are two future directions for geothermal:

  1.  Drilling down to temperatures of 1000 degrees F, where the fluid will be supercritical, multiplying the potential available energy by a factor of ten.

  2.  Tapping hot dry rock, a resource that is located anywhere in the world if you drill deep enough.  There are technical problems, of course, but that is what engineering is all about.  It is estimated that this option can produce all the world energy needs for centuries to come.

The big deal about geothermal is that it is like a normal fossil or nuclear power plant, for baseload electricity is produced.  Ocean thermal energy conversion also provides steady, high quality power.  Wind and sun electricity are intermittent and undependable.

The economics of geothermal are also of special advantage, as the cost falls in the range of coal/nuclear and wind energy, lower than any solar alternative:

What is the future for Hawaii.  Well, when my staff at the Hawaii Natural Energy Institute did the R&D for this option in the 1980's, Judge David Ezra, the Federal Judge, sided with the environmentalists, rain forest advocates, marijuana growers and local residents, almost all who opposed the possible economic turmoil, environmental insults, religious connotations and general noise and smells of this resource, effectively killing widespread development for the State of Hawaii.  A 500 MW submarine cable project analysis by Pirelli showed that it was commercially viable if the resource were there.  Ironically enough, that undersea electrical cable debate today to bring Big Wind from Lanai and Molokai to Oahu has now resulted in geothermal energy again being touted as a better idea.  This same Judge Ezra is still around, and is adjudicating this possibility, this time supported by some Hawaiian activists, like Mililani Trask:


A good history of geothermal energy in Hawaii was written by Don Thomas, et al.  Henry Curtis, Executive Director of Life of the Land, has a really terrific current summary of geothermal energy.  I urge you to click on his link.


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