Mitsubishi Heavy Industries patents solution for lower plant facility costs
Mitsubishi turbine at the Hellisheidi geothermal power plant, Iceland (source: flickr/ ThinkGeoEnergy, creative commons)
Francisco Rojas
22 Jul 2014
In a newly granted patent, Mitsubishi Heavy Industries has secured rights to an invention that would use air instead of water steam for turbine operation.
Under normal circumstances, when a geothermal power plant taps the heat of the earth, it does so by drilling a hole and extracting hot water and steam that is separated and having the steam pass through a turbine to generate electricity. The issue raised by researchers from Mitsubishi Heavy Industries is that the steam and hot water cannot be released into the land, since the geothermal brine might contain chemicals that could be hazardous for the environment and also, without reinjection, the geothermal well might run dry. Performing these tasks among other usual operations incur on operational costs that plants have to assume.
In order to solve this matter, these scientists prose a way to use air as the operating fluid instead of steam or brine, thereby reducing costs and wear to equipment and installations by simplifying operations and reducing processes.
According to the official post in the patents office website, the invention is described as “A geothermal power-generation system comprising: a compressor that compresses air; an air supply pipe embedded in a ground to a predetermined depth from a surface of the ground; a heat exchange unit that is connected to a distal end of the air supply pipe and performs heat exchange between air and geothermal heat; an air discharge pipe that is connected to the heat exchange unit and embedded in the ground from the surface of the ground; a turbine that obtains a rotational force by heated compressed air heat exchanged by the heat exchange unit; and a generator that generates power by a rotational force inputted from the turbine, wherein the heat exchange unit includes a columnar main body and a plurality of partition walls for defining a plurality of fine pores within the columnar main body, wherein the heat exchange unit includes a first heat exchange unit that is connected to a lower end of the air supply pipe and a second heat exchange unit that is connected to a lower end of the air discharge pipe, and the lower end of the first heat exchange unit is connected to the lower end of the second heat exchange unit by a U-shaped connecting piping.”
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Source: US Patents and Trade Office via 4Traders Website
