Green Power Research

Interesting takes on the world of Green Power

The power source with the largest water consumption

by Tony - March 1st, 2016.
Filed under: Biofuels and related power, Energy, Water. Tagged as: , , , , .

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I was preparing for a presentation I was giving to the Eco Green Group of Silicon Valley on the water energy nexus. While in the process of researching the renewable power sources which used the lowest and highest amounts water in their energy production I encountered something I found surprising.

Two ears of corn isolated over black

Two ears of corn isolated over black

The lowest water consumer

Wind Power wound up being the lowest consumer of water, requiring no water while solar power uses only 1% of the water used in conventional fossil fuels.  The water requirement in solar panels results from a small amount of water needed to wash dust off the panels which if allow to accumulate up will hamper a panel’s energy production.

The highest water consumer

According to coal uses 1,000 gallons of water per megawatt hour produced while nuclear power uses 800 gallons per megawatt hour. Natural Gas uses 300 gallons per megawatt of power produced.

Conventional fossil fuels use water to produce steam in addition for using water for cooling purposes. Therefore, it seems logical since wind and solar power does not use steam or cooling by water these would be expected to be pretty low. Interestingly enough, the largest consumer of water is not so straightforward.

Ethanol, which is used as an additive in gasoline in addition to being viable as a biofuel had the largest water consumption of any renewable power source because of the water needed to grow the corn which it eventually used to produce ethanol.

Ethanol is produced from corn typical uses the dry grind process in which corn grain is milled, then mixed with water to create “mash.” Enzymes are added to the mash and this mixture is then cooked to convert the starch into sugars. Yeast is used to ferment the sugars into ethanol and carbon dioxide and the ethanol is purified to create fuel ethanol.

How much water?

Roughly 3 to 15 gallons of water per gallon is used to produce one gallon of ethanol which is more than twice the rate of water usage for refining gasoline.  Once the water to produce the corn and prepare the ethanol is taken into account approximately 50 – 100 gallons of biofuel are required for per megawatt hour of power produced. Roughly on the high end of the ranges 1,500 gallons for water for every megawatt produced using biofuels.

Until the time comes when wind and solar power generate more of our energy requirements than they do at present time the water energy nexus will require everyone to think about the water consumption used to supply the electricity ubiquitous with everyday life.

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