Geothermal vent in Iceland

Written by Carolyn Lieberg

Geysers, hot springs, and volcanoes all present vivid evidence of the heat under the earth’s crust. As countries seek alternatives to fossil fuels, more effort is being spent on developing ways to convert that heat to electrical power.

Geothermal energy has long been used to directly heat buildings or in heat exchange units for heating and cooling. Iceland, with a population of about 300,000, is very close to powering the electrical and heating needs of its entire country with renewable resources. The island nation continues to expand geothermal power production for additional industrial and commercial uses. One reason Iceland can make such good use of geothermal technology is that there is ready access to what are called hot spots: locations on the earth where steam rises from cracks or where the crust is thin enough to allow easy drilling to the heat source.

According to Karl Gawell and Griffin Greenberg, who compiled a report on international developments last year, “Recent talks with major aluminum companies about relocating” to Iceland are promising due to the abundance of electricity there and may even inspire the construction of additional facilities.
Geothermal energy is created in a manner similar to backyard compost piles, where decomposing vegetable matter creates heat. Under the earth’s crust, the decomposing materials include uranium and potassium. In the process, magma is formed – the molten rock that occasionally blasts through in volcanoes.
This heat is generally tapped in one of three ways: The simplest exchange occurs when rising steam is focused on turbines that create electricity.

A second way to tap geothermal energy is accomplished by bringing up hot water – 360 degrees F – and depressurizing it into steam, which then runs the turbine.

The third method is to run hot water tubes through a heat exchanger in order to heat a liquid such as ubotane in a closed loop, much like a refrigerator. This liquid creates steam with available water to turn the turbine.

“We’ve determined that heat mining can be economical in the short term,” said Jefferson Tester, head of an MIT panel calling on the US government to aid in additional R&D funds and offer policy incentives. The environmental advantage, added Tester, a professor of Chemical Engineering at MIT “is due to low emissions and the small overall footprint of the entire geothermal system, which results because energy capture and extraction is contained entirely underground, and the surface equipment needed for conversion to electricity is relatively compact.”

Brian Anderson, assistant professor at Western Virginia University and also a member of the panel said, “Drilling and reservoir technologies [that are] used to mine heat have many similarities to those used for extracting oil and gas. As a result, the geothermal industry today is well connected technically to two industry giants in the energy arena, oil and gas producers and electric power generators.”

Inventions that rely on other facets of the geothermal potential include the Power Tube, a device that turns heat into electrical power without the use of water. Doyle Brewington says he uses geomagmatic technology as the basis for the development of his Power Tube. He is in the process of securing a former missile silo for a virtual test of the Argus A1, which he says will produce up to 1.5 MW. He has been contacted by several countries about his invention. “Our plan is to set up 20 assembly points around the globe,” Brewington said, and cited Merco-Sur in Chile as one of them.

Geothermal plants using more conventional methods of heat-to-electricity transfer are in varied phases of production in Australia, Ethiopia, Djibouti, Indonesia, India, and others. Italy, where the first experiment of turning geothermal steam into electricity took place in 1904, has continued to refine and promote the technology. Plans are underway for a joint project with Chile.

The Geothermal Energy Association estimates that the number of countries creating power with geothermal technology will rise from 21 countries in 2000 to 46 in 2010. The group projects a production of 13,500 MW, a substantial growth over the 2005 figure of 8932 GW. This growth is sorely needed.
In the past 25 years, worldwide energy use has risen by about 70 percent and it continues to rise 2 percent per year. Both developing and developed countries are responsible for the increase. Fortunately, the rise in the use of renewable sources of energy is helping meet this demand.