When it comes to unintended consequences, there is no greater example of good intentions gone wrong than the complicated relationship between renewable energy and water. Many of you are probably aware that biofuels can be water intensive, depending on the source. In general, it takes about 4 gallons of water to produce 1 gallon of biofuel, but it can take upwards of 2,500 gallons of water to produce 1 gallon of ethanol. But fuels are not the only water-intensive renewable power source.
Of course, traditional power sources are also water intensive, as this graph from the California Energy Commission illustrates:
WATER CONSUMPTION—CONVENTIONAL POWER PLANTS
|
Technology
|
gallons/kWh
|
liters/kWh
|
|
|
|
Nuclear
|
0.62
|
2.30
|
|
Coal
|
0.49
|
1.90
|
|
Oil
|
0.43
|
1.60
|
|
Combined Cycle
|
0.25
|
0.95
|
Nevertheless, as long as water and energy are intertwined, we must make sure to take into account all possible consequences of any energy policy. For example, while solar power is in many ways an ideal power source, the manufacture and operation of large-scale solar power systems requires vast amounts of water. Water is the traditional cooling agent for most large-scale solar plants. Additionally, many large-scale solar facilities are located on vast swathes of land that are ecologically fragile and water-scarce (for example, the American Southwest). There are some solutions available, from air-cooled technology—which uses 90% less water—to solar dish or photovoltaic technologies that don’t require steam engines and cooling water.
But not all renewable energy sources are created equal when it comes to water use. Wind turbines, for example, don’t require water for anything other than minor turbine maintenance. And microbial fuel cells offer the best of both worlds because they use naturally occurring bacteria to convert wastewater into clean water while at the same time producing electricity.
What do you think? When it comes to water and renewable energy, is it a “lesser of two evils” situation, or can we hope for something better?=
To read more about the water and solar in the Southwest, go to: http://www.msnbc.msn.com/id/30283556/