The C-Net Green Tech Blog has an interesting summary of how much water is used by the different energy technologies that we use.

You would probably assume, as I did, that this refers to hydroelectric power, such as the large amounts used here in New York State and in our adjoining Canadian provinces of Québéc and Ontario. You’d be wrong.

Now that fresh water is becoming an increasingly scarce resource, it becomes important to recognize that ethanol, biodiesel and nuclear fission have some of the highest demands for fresh water amongst energy technologies.

Of particular concern are biofuels.

I used to be an avid proponent of biodiesel, on the grounds that biodiesel production can take something out of the waste stream and turn it into something useful. Unfortunately, most, if not all, of the biodiesel commercially available is made from 100% virgin oil.

At the same time, ethanol is the result of a fermentation process (which results in around 50% of the inherent energy being consumed by the fermenting bacteria, as well as being water-intensive) followed by a distillation process (which consumes fuel).

I will heave a deep sigh and refrain from discussing nuclear power for now.

Ultimately, every energy technolgy we have, except for nuclear, operates on energy that has been captured by the sun, either biologically (as with fossil fuels, ethanol, biodiesel and biomass), or mechanically (wind and rain are both results of the sun heating the earth), and so, I must ask, why don’t we just go to the source?