Speculation, economic growth, and global tensions recently drove oil prices to around $50 per barrel. In a world in which energy consumption is constantly rising, the potential to tap geothermal energy is stunning.
To understand why, let’s examine the technology of geothermal power, including its pluses and minuses.
When tectonic plates crash into each other, and volcanoes, molten rock, and hot springs are present, an incredible amount of heat is generated. After pumping water into the ground, the heated water can be used to make electricity. Unlike the limited supply of oil, there is an endless supply of this energy.
The main geothermal areas of this type are located in New Zealand, Japan, Indonesia, the Philippines, Iceland, Italy, eastern Africa, as well as California, Hawaii, and Mexico, according to a report in The Guardian by Paul Brown.
In many of these places, such renewable energy sources are already being extensively tapped. For example, in the Philippines, geothermal already supplies 15 percent of that nation’s energy needs, and hydroelectric power provides 19 percent. And it plays a big part in a new $25 billion Filipino government plan to lift the impoverished nation out of oil dependence.
In his “energy independence agenda,” Filipino Energy Secretary Vincent Perez acknowledged an urgent need to cap growth in last year’s $4 billion bill for crude oil and oil products to feed motor fuel and power generation demand. Today, the Philippines is already the world’s second largest geothermal producer, converting volcanic power into electricity.
Under the new plan, the Philippines will overtake the United States as the leading producer of renewable powerby developing 10 proposed
new geothermal fields. As such, geothermal will be a big portion of the additional 5,200 megawatts of power generating capacity scheduled to come online by 2014, to meet rising demand, according to the Manila Bulletin.
After a number of years of decreased activity, the United States is also becoming more active in exploiting geothermal energy. Daniel Kunz, president of Boise-based U.S. Geothermal, has spent three years securing energy rights and leasing and buying property, and he expects to put a proposed 10-megawatt geothermal generation plant in Idaho online by 2006. As the Associated Press reports, one reason the project can move so fast is that much of the work was done by the U.S. Department of Energy, which operated the site as a geothermal demonstration project from 1974 to 1982.
U.S. Geothermal bought the facility and one square mile of land from the company and has negotiated leases and energy rights for another five square miles. That means the plant will have more than 3,700 acres of geothermal potential to tap. The plant is expected to eventually have a capacity of 90 megawatts. That’s enough power to run about 6,000 typical American homes.
These existing and planned geothermal wells tap energy from a mix of boiling water and steam formed underground at temperatures between 200 and 340 °C. In these plants, steam is separated and passed through a turbine at the surface.
However, a pioneering project in Iceland is now in the process of drilling through this “mid-temp region” of the earth’s crust and going straight to the source of the heat: magma. To extract energy from magma, the Icelandic team must devise a convenient way of getting that heat to the turbine: the magma itself is far too hot.
Fortunately, technology is now being developed to exploit these dramatically higher temperatures to achieve much higher efficiencies. Iceland’s so-called IDDP effort will use water that sits in a reservoir directly on top of the magma. As explained in an August 2004 New Scientist article, the extreme conditions encountered here change that water into a “supercritical fluid”: a mix of liquid-like, hydrogen-bonded clusters of water molecules dispersed in a gas-like phase that makes an excellent solvent for all kinds of chemicals. It is this supercritical fluid that will be sent up through the well to the turbine.
To handle the immense forces involved, this wellhead will be designed to handle fluid pressures of more than 220 times normal air pressure. Similarly, the well itself will be lined with three layers of cemented steel casing for over half its length. The casing will have to be carefully designed to handle the expansion caused by temperatures ranging from 30 °C to more than 500 °C. If all goes according to plan, and the team hits supercritical conditions as expected, the fluid will be piped up for testing. Then all they have to do is work out how to deal with it.
At this point, the results are highly speculative. Part of the problem is that nobody knows what temperatures and pressures to expect, and even less what the chemical composition of the fluid will be. In Iceland, geothermal teams have been drilling to 2 kilometers for decades, so they pretty much know what the fluids will be at that depth. However, no one knows what they will find at 5 kilometers.
As the New Scientist report explains, most experts speculate that they will meet hot, high-pressure seawater modified by boiling and reacting with the surrounding rock. It will contain all kinds of chemicals such as potassium chloride and calcium, plus pretty much any metal you care to think of. This could cause some headaches. However, we predict that the long-term outlook for geothermal energy will be positive.
First, if the geothermal teams manage to tame the fluid, converting its energy into electricity using a turbine should be relatively easy. They can readily convert the supercritical fluid to superheated steam and steam is something these engineers are used to working with. The big difference is that while a flow of 2 kilograms per second of conventional steam produces 1 megawatt of power, the same flow rate of supercritical steam could, theoretically, generate 10 megawatts. And that’s where the big pay-off comes, with a geothermal well that’s effectively 10 times as efficient as existing wells. With an energy source this efficient, it will be very cost-effective to produce hydrogen fuel by electrolyzing water, to fuel Iceland’s clean-energy revolution.
Second, this new technology may become a winner in the U.S. Iceland’s commitment to hydrogen is already clear. The world’s first hydrogen filling station opened just outside Reykjavik in April 2003 to fuel three city buses. There are plans to convert the entire fishing fleet, and eventually the whole country, to run on hydrogen. So far, the U.S. has done more with wind and solar energy, while Japan has mostly relied on nuclear power. It appears that Iceland and the Philippines are the leaders in geothermal. Currently, the U.S. Geothermal Inc. project in Idaho is about the only American effort now underway, but if Iceland is successful, we expect to see support grow rapidly for this revolutionary energy source in the U.S.
References List : 1. The Guardian, September 11, 2004, "The Balance of Power: We Can Still Have All the Electricity We Want in 2020," by Paul Brown. ⓒ Copyright 2004 by Guardian Newspapers Limited. All rights reserved.2. Manila Bulletin, September 11, 2004, "Oil-Dependent RP Taps More Geothermal Power," by Dolly Aglay. ⓒ Copyright 2004 by Manila Bulletin Publishing Corp. All rights reserved.3. Associated Press, September 18, 2004, "Digging Deep for Energy Solutions," by Chip Thompson. ⓒ Copyright 2004 by The Associated Press. All rights reserved.4. New Scientist, August 14, 2004, "Deep Heat," by Caroline Williams. ⓒ Copyright 2004 by Reed Business Information Ltd. All rights reserved.
