Seems like that's the way it is with water and energy these days. First, the good news. Then, the bad news. Remember the rush to ethanol?

A new study by the folks at Pacific Northwest Laboratory published in the journal Water Resources Research claims that algal biofuels could replace 17% of the USA's imported oil. But the amount of water required could put the kibosh on such a plan.

Here are the citation and abstract (you will have to pay to download the entire article unless you are a member of AGU):

Wigmosta, M. S., A. M. Coleman, R. J. Skaggs, M. H. Huesemann, and L. J. Lane (2011), National microalgae biofuel production potential and resource demand, Water Resour. Res., 47, W00H04, doi:10.1029/2010WR009966 Microalgae are receiving increased global attention as a potential sustainable “energy crop” for biofuel production. An important step to realizing the potential of algae is quantifying the demands commercial-scale algal biofuel production will place on water and land resources. We present a high-resolution spatiotemporal assessment that brings to bear fundamental questions of where production can occur, how many land and water resources are required, and how much energy is produced. Our study suggests that under current technology, microalgae have the potential to generate 220 × 109 L yr−1 of oil, equivalent to 48% of current U.S. petroleum imports for transportation. However, this level of production requires 5.5% of the land area in the conterminous United States and nearly three times the water currently used for irrigated agriculture, averaging 1421 L water per liter of oil. Optimizing the locations for microalgae production on the basis of water use efficiency can greatly reduce total water demand. For example, focusing on locations along the Gulf Coast, southeastern seaboard, and Great Lakes shows a 75% reduction in consumptive freshwater use to 350 L per liter of oil produced with a 67% reduction in land use. These optimized locations have the potential to generate an oil volume equivalent to 17% of imports for transportation fuels, equal to the Energy Independence and Security Act year 2022 “advanced biofuels” production target and utilizing some 25% of the current irrigation demand. With proper planning, adequate land and water are available to meet a significant portion of the U.S. renewable fuel goals

Wow - replacing 17% of our imported oil at the expense of 25% of our irrigation water? But perhaps all that water would not be required.

Science Daily reports:

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. Researchers at the Department of Energy's Pacific Northwest National Laboratory found that water use is much less if algae are grown in the U.S. regions that have the sunniest and most humid climates: the Gulf Coast, the Southeastern Seaboard and the Great Lakes. "Algae has been a hot topic of biofuel discussions recently, but no one has taken such a detailed look at how much America could make -- and how much water and land it would require -- until now," said Mark Wigmosta, lead author and a PNNL hydrologist. "This research provides the groundwork and initial estimates needed to better inform renewable energy decisions."

The article continues:

Wigmosta and his co-authors provide the first in-depth assessment of America's algal biofuel potential given available land and water. The study also estimated how much water would need to be replaced due to evaporation over 30 years. The team analyzed previously published data to determine how much algae can be grown in open, outdoor ponds of fresh water while using current technologies. Algae can also be grown in salt water and covered ponds. But the authors focused on open, freshwater ponds as a benchmark for this study. Much of today's commercial algae production is done in open ponds.

More on the land and water use aspects:

The researchers found that 21 billion gallons of algal oil, equal to the 2022 advanced biofuels goal set out by the Energy Independence and Security Act, can be produced with American-grown algae. That's 17 percent of the petroleum that the U.S. imported in 2008 for transportation fuels, and it could be grown on land roughly the size of South Carolina. But the authors also found that 350 gallons of water per gallon of oil -- or a quarter of what the country currently uses for irrigated agriculture -- would be needed to produce that much algal biofuel. The study also showed that up to 48 percent of the current transportation oil imports could be replaced with algae, though that higher production level would require significantly more water and land. So the authors focused their research on the U.S. regions that would use less water to grow algae, those with the nation's sunniest and most humid climates. 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.

The story concludes:

"Water is an important consideration when choosing a biofuel source," Wigmosta said. "And so are many other factors. Algae could be part of the solution to the nation's energy puzzle -- if we're smart about where we place growth ponds and the technical challenges to achieving commercial-scale algal biofuel production are met." Next up for Wigmosta and his colleagues is to examine non-freshwater sources like salt water and waste water. They are also researching greenhouse ponds for use in colder climates, as well as economic considerations for algal biofuel production.

Read the entire article; it is well worth it.

And so is this continued research.

Thanks to Dorian Roffe-Hammond for bringing this to my attention.

"I happily support corn ethanol, all forms of ethanol, research for cellulosic ethanol, biodiesel." -- Hillary Clinton, 2007

"We are providing a single industry [ethanol] with a guaranteed market for its products -- subsidies on top of subsidies on top of subsidies and, on top of that, protection from liability. What a sweetheart deal." -- Hillary Clinton, 2002