Supercritical steam has already been used in coal-fired and nuclear power plants. The mechanism by which it yields higher efficiency is complicated, but ultimately it boils down to this: steam turbines need very hot steam in order to produce power, and supercritical steam is much closer to this temperature than cooler steam, says Ashok Malhotra, who literally wrote the book on the subject (Thermodynamic Properties of Supercritical Steam). As a result, very little energy is wasted in transferring heat from the steam that comes out of the ground to the steam that will spin the turbine. In addition, the entire system can be constructed under the assumption that steam and water don't have to be separated in the early phases of the power generating cycle—because at these temperatures and pressures, these usually distinct phases of water are literally one and the same.
Tapping supercritical steam will require drilling deeper than any geothermal project has ever drilled before; as deep as three miles (five kilometers) below the surface. No one knows exactly what the water will be like at that depth, according to Benedikt Steingrímsson, chief project manager of ÍSOR.
"We have already reach[ed] temperatures of 360 degrees C [680 degrees F] or more only at a depth of 2.2 kilometers [1.4 miles]," Steingrímsson says. "So we're already very close to the supercritical point. The heat is certain—how much fluid there is, what its chemical properties are, and its gas content are unknown."
Dissolved solids, toxic metals and corrosive gases are only some of the obstacles the IDDP will have to overcome in the next 10 years—also at issue is the pressure of the supercritical fluid, which is 10 times greater than existing instruments and power plants have been designed to handle.
"Everyone knows it won't turn on lightbulbs anytime soon," Thórhallsson says. But surely Sturlusson, whose offspring still live in Iceland to this day, would have been proud.
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3 Comments
Add CommentDear Sirs!
Reply | Report Abuse | Link to thisThank you for excellent article about Iceland's geothermal energy. I do want however to comment on your geography. From the geothermal spa of the Blue Lagoon you can not see the Nesjavellir Power Plant but you can see the Svartsengi Power Plant operated by Hitaveita Sudurnesja (Sudurnes District Heating Inc.)
Teitur Gunnarsson, M.Sc., Manager Chemical Processes, Mannvit Engineering, Reykjavik, Iceland.
Super critical steam seems like the best renewable resource so far! We should invest in figuring out the ins and outs (no pun intended) of extracting, or drilling for, this sustainable energy. Exporting this geothermal power will inevitably help the environment and continue to encourage sustainable energy research. The Blue Lagoon is a prime example of how popular this resource can be. We should keep on with the Green Energy!!!!
Reply | Report Abuse | Link to thisYes... to more sustainability!
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