In addition to affecting farmers, turning off the tap is changing the way we generate solar electricity. Currently, solar-thermal plants generate electricity through mirrors redirecting solar energy to a boiler. The solar energy heats up liquid sodium which turns liquid water into water vapor. The steam turns a turbine, generating electricity.
The water needs to be cooled, which is achieve through evaporation. Since so much water is lost through evaporation, it must constantly be replenished. An alternative method of cooling using fans and heat exchange saves most of the water, but the procedure adds costs.
Currently, 35 large-scale solar projects are planned for California alone. These projects can generate 12 GW of electricity, enough to power 9,000,000 homes. Although these are great plans, they will take a heavy toll on water.
One proposed project, the Ivanpah dry-cool project in California, plans to consume 25 million gallons of water per year. Most of this water is required to clean the mirrors. In comparison, a wet-cool solar-thermal plant half the size of Ivanpah would require 705 million gallons a year using a dry-cool system.
Obviously, dry-water systems are the way to go. With the American Southwest being a desert, it is important that we conserve water. Until we are able to efficiently purify ocean water, we need to find alternatives to consuming valuable fresh water for cooling solar plants.
Original Article: Solar-Thermal Electricity Generation Faces Water Use
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