Concentrating solar needs huge amounts of water

A solar thermal plant in a desertConcentrating Solar Thermal is a fantastic energy source and some experts estimate that it could answer a quarter of the global electricity needs by 2050 if large plants were installed in sunny deserts.

However the New York Times notes that this energy source use significant amounts of water. Since this resource is already scarce in these areas this energy source already triggers tensions.

This is a further example of how no energy source is perfect and that energy efficiency and conservation are absolutely vital to our civilization.

Here is what the New York Times noted :

“When push comes to shove, water could become the real throttle on renewable energy,” said Michael E. Webber, an assistant professor at the University of Texas in Austin who studies the relationship between energy and water.

Conflicts over water could shape the future of many energy technologies. The most water-efficient renewable technologies are not necessarily the most economical, but water shortages could give them a competitive edge.

In California, solar developers have already been forced to switch to less water-intensive technologies when local officials have refused to turn on the tap. Other big solar projects are mired in disputes with state regulators over water consumption.

(…) Many projects involve building solar thermal plants, which use cheaper technology than the solar panels often seen on roofs. In such plants, mirrors heat a liquid to create steam that drives an electricity-generating turbine. As in a fossil fuel power plant, that steam must be condensed back to water and cooled for reuse.

The conventional method is called wet cooling. Hot water flows through a cooling tower where the excess heat evaporates along with some of the water, which must be replenished constantly.

An alternative, dry cooling, uses fans and heat exchangers, much like a car’s radiator. Far less water is consumed, but dry cooling adds costs and reduces efficiency — and profits.

(…) In California alone, plans are under way for 35 large-scale solar projects that, in bright sunshine, would generate 12,000 megawatts of electricity, equal to the output of about 10 nuclear power plants.

This kind of topic clearly reminds me that albeit there is water almost everywhere, it is not in the needed amounts in many places. Desalination has a bright future…

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