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Monday, May 7, 2018

THE ERUPTION AND FUTURE OF GEOTHERMAL ENERGY IN HAWAII

While this blog site unbecame being a daily a week ago, I've pretty much maintained continuity because of the volcanic eruption in the middle of Leilani Estates in Puna on the Big Island of Hawaii.  One of my interest areas was the fate of Puna Geothermal Ventures (PGV), for I've been associated with that technology for 45 years when I was a reservoir engineer for the Hawaii Geothermal Project, which succeeded with the hottest well in the world.  The closest fissure is less than a mile from the power plant, but the lava flow at this moment seems to be moving away.  Yet, there could be more fissures, and the wells drilled by the company could become a contributing factor.

I kept hearing about huge volumes of exploding gases at the PGV facility and couldn't quite understand what they were talking about.  In our well, the steam went directly into the turbine to turn a generator to produce electricity.  What gases?  Then it occurred me that the original developers of PGV included Ormat, a company with Israeli influence, and they did feature a binary system which perhaps used a secondary fluid that could be explosive.

Yesterday I read a news article, and to quote:

Councilwoman for the district, Eileen O'Hara, says the main concern is the nearly 60,000 gallons of pentane stored on site. Pentane is a highly flammable liquid.

Surely enough, the technology has changed.  At one time, only direct steam turbines were used.  Today, about a third of all systems are binary, and the secondary fluid is normally some form of pentane or butane.  One added advantage of this process is that the turbine, the most expensive part of the above-ground equipment package, required less maintenance.  However, initial costs are higher and, yes, if inundated by a lava floor, there is serious explosion potential.  Building this facility right over the East Rift Zone was not a wise decision, and the use of a flammable fossil fuel gas was doubly idiotic.

Soon after we succeeded with HGP-A in Puna, the University of Hawaii pioneered the development of ocean thermal energy conversion (OTEC) at Keahole Point on the other side of the Big Island.  Lockheed first succeeded with Mini-OTEC in 1979, a closed cycle process, and my team at the Pacific International Center for Technology Research in the early 1990's using open cycle.  

The difference is similar to that geothermal direct/binary issue.  Closed cycle uses a secondary fluid, usually some kind of refrigerant (like substitutes for freon) or ammonia, both of environmental concern.  Our open cycle OTEC reactor only used natural cold water and surface ocean waters, and produced freshwater as a by-product.

Well, back to geothermal energy, when I was active more than four decades ago, the world had less than 2000 MW of geothermal energy.  Today, the grand total is approaching 15,000 MW.  Here is a map that shows where future power plants might have been located on the Big Island.  We can forget about that 850 MW potential until better and cheaper directional drilling technology is developed.


Toll thus far, zero humans, 35 structures (mostly homes), ten fissures...and, oh great, PGV can't move the 60,000 gallons of pentane because they don't have the containers to do this.  But they've been ordered.

KITV has an hourly update of the current eruption in Puna.  The U.S. Geological Survey provides a daily summary.

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