However, a new study shows that being smart about where we grow algae can drastically reduce how much water is needed for algal biofuel. Growing algae for biofuel, while being water-wise, could also help meet congressionally mandated renewable fuel targets by replacing 17 percent of the nation’s imported oil for transportation, according to a paper published in the journal Water Resources Research.
Offsetting oil with increased water usage should raise a red flag, so here are some numbers to ground speculation:
But the authors also found that algae’s water use isn’t that different from most other biofuel sources. While considering the gas efficiency of a standard light-utility vehicle, they estimated growing algae uses anywhere between 8.6 and 50.2 gallons of water per mile driven on algal biofuel. In comparison, data from previously published research indicated that corn ethanol can be made with less water, but showed a larger usage range: between 0.6 and 61.9 gallons of water per mile driven. Several factors – including the differing water needs of specific growing regions and the different assumptions and methods used by various researchers – cause the estimates to range greatly, they found.
Because conventional petroleum gas doesn’t need to be grown like algae or corn, it doesn’t need as much water. Previously published data indicated conventional gas uses between about 0.09 and 0.3 gallons of water per mile.