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Dry rock geothermal methods are currently being used in parts of the world for energy production, but Missimer says that the heat can be used in more efficient ways, especially with desalination. Details of the new research constructing a "geothermal energy-water campus" will be presented on Monday at the 2018 Geological Society of America Annual Meeting in Indianapolis, Indiana.
Usually, geothermally heated water from the ground is converted to steam, that steam powers a turbine to create electricity, then the heated water is vented to the atmosphere while it's still hot—still over 100 degrees Celcius[sic] in most cases. Instead of venting, the team wants to use that hot steam in their desalination processes.
The first desalination process is multiple effect distillation (MED), which requires hot water (above 100 degrees Celsius), but the second process, adsorption desalination (AD), can be run on cooler water, says Missimer. As the steam moves through the system and cools, it is still effective for powering desalination. "Now you have an efficient system where you have conserved the latent heat that you've captured in the ground through three processes: turbine electricity generation, MED and AD."
At the end of the desalination process, Missimer says that distilled water and chilled water (from the AD process) are the final products. While the distilled water can be consumed, even the chilled water is reused—the cool water can be recycled through the plant to help with air conditioning.
(Score: 0) by Anonymous Coward on Tuesday November 06 2018, @09:30PM
It's not at all the same thing: the heat from a nuclear plant you are talking about isn't "wasted". Nuclear power plants generate electricity by operating a heat engine. In order to operate a heat engine you need a hot side and a cold side -- the bigger the temperature difference between the two sides the more energy you get out of it. The hot side of this engine is the reactor, and the cold side is the cooling towers (or more typically, it is a large body of water). Thermal energy moves from the hot side to the cold side, producing useful work.
To do the reverse, taking that energy back out of the cold side, requires work input. If everything was perfectly efficient, to take all the energy you dumped into the cold side back out requires, at minimum, the same amount of work you got out of the generator in the first place.