Water needed to produce various types of energy

Hello, All -- Although the cost efficient, energy efficient compact fluorescent light bulb (CFL) has been on the global market for over a decade, the mass of people are unable or unwilling to take what should be an obvious step of saving money by purchasing new technology. This is why state and national governments -- including the USA -- have needed to create extraordinary legislative mandates to phase out or ban the further use of inefficient, wasteful, old technology incandescent lights.

Researchers at Virginia Tech have now provided water-use information tied to old technology and new technology light bulbs that should be of value as a selling point for efficient lighting, particularly in water-short regions like our American Southwest.

A 60-watt incandescent light bulb, burning for 12 hours per day per year, requires between 3,000 and 6,000 gallons of water at the ("conventional") power plant that produces the electricity to power the bulb. Substituting a CFL with the equivalent light output (in this case, a 13-watt CFL) would save 2,000 to 4,000 gallons of water per year.

The researchers conclude that the equivalent of one 60-watt incandescent light bulb burning for 12 hours per day in the approximately 111 million USA homes results in water usage as high as 655 billion gallons of water a year.

The article treats 11 types of energy sources, including coal, fuel ethanol, natural gas, and oil; and five power generating methods, including hydroelectric, fossil fuel thermoelectric, and nuclear methods.

However, the article does not mention wind and solar photovoltaic power arrays that require virtually no water.

The 11 types of energy sources mentioned in the article require significant amounts of water, as well as a water-supply infrastructure. Some sample numbers from other sources show the following:

Nuclear (> 800 gallons), coal (> 750 gallons), biofuels (approx. 750 gallons), and natural gas (> 600 gallons) power plants require about 600 to 800 gallons of water for every megawatt hour of energy produced. IGCC and Combined Cycle power plants require about 200 gallons of water for every megawatt hour of energy produced. Concentrated solar thermal power plants (where solar reflectors heat liquids to run turbines) require about 750 gallons of water per megawatt hour of energy produced. [Note that concentrated solar thermal power is very different from solar photovoltaic power.] The water consumption figures in this paragraph mainly represent cooling water that is evaporated into the atmosphere as steam.

By comparison, solar photovoltaic (PV) and wind power require no water.

The American West is a water-short region where scientists and water managers are already looking at 20 percent reductions in water supply over the 21st century due to the drought impacts of climate change.

-- Bill Brown
Taos, New Mexico
www.nmglobalwarming.org

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