If cartoonist Gary Larson's wickedly funny hand had been set loose upon our energy problems, the result might well be a depiction of a group of yelping, muscular algae, wearing cowboy hats and mounted upon motorized sea bikes, herding enormously bulbous fat kids into a holding area labeled: "Energy Extraction Farm." The cartoon caption would read: "Yepp, Pardner, I knew Lip-O-Suction would be a 'portant energy technology some day!"
What a fast-food lifestyle has done to kids, some scientists want to do to pond scum: make 'um fatty, fat fat! It seems, in many ways, Larson's topsy-turvy whimsy has inspired a vision of our energy future: a future filled with genetically engineered, ginormously fat algae to be harvested as fuel.
We're not talking about slightly plump algae. No! To be desirable as fuel, pond scum -- a strictly technical, politically correct and nonpejorative term -- will tip in at 80 percent fat!
"Why?" you ask. Because harnessing algae as transportation fuel is all about a hunt for petroleum replacements to be used for things electricity cannot accomplish. For example, a jet plane can't fly on batteries. However, grossly obese pond scum can be transformed into energy-dense jet fuel, gasoline, diesel and similar liquid fuels roughly comparable to current petroleum sources.
Early indicators are that the amount of fuel produced from a very sunny acre of algae-infused water, ranges between 750 and 2000 gallons of oil per year. The energy content of the resulting fuel produced is about 90 percent that of gasoline, though precise numbers remain fuzzy. That result is consistent with the notion of approximately 1 percent efficient photosynthetic conversion of sunlight energy into stored chemical energy.
At its core, this process is farming. Among the chief concerns: nutrients, water, crop protection and pests -- yes, algae have predators. Algae is the crop! Oily biofuel is the byproduct.
However, the fundamentals of getting from carbon dioxide, nutrients, and an acre of water-covered land, and finally through the processes needed to separate, pump, transport and refine a fuel derived from algae, require many energy-devouring processes. This suggests the net energy produced from an algae crop may be lower. How much lower remains to be seen.
Indeed, cultivating corn for ethanol to be used as a transportation fuel requires more energy than it produces, something which was entirely predictable, and a bitter lesson for some environmentalists.
Many of the algae-to-oil process steps may be capable of being supplemented with energy from other renewable sources. For example, water has been pumped mechanically without electricity via windmills since the Dutch used them to dewater their lands. Growing algae requires a good deal of water pumping which might be done using simple, old-style mechanical windmills.
A key feature of "oil biosynthesis" is that it is best induced by depriving the algae of nitrogen sources: nitrates, ammonium, etc. Nitrogen leads to protein synthesis which leads to reproduction, not larding up. A minor detail: fertilizers have almost everywhere raised the level of nitrogen compounds in our water supplies.
Moreover, algae respire in the absence of sunlight, meaning they consume oxygen at night. This suggests that some access to the atmosphere is necessary.
Based on the April 24, San Diego Center for Algal Biotechnology (SD-CAB), Algal Biofuels Symposium held at the Salk Institute, considerable intellectual effort is going into changing algae genetically, manipulating their chemical environment, and promoting efficient production of far greater percentages of fat (lipids). What can be done in a test tube is spectacular.
What is not as clear is how useful these techniques will be if applied en masse in the wilds of the outdoor environment, the location which seems inevitable for economical, large-scale operations. After all, the objective is to achieve a means for efficiently converting solar energy into chemical fuel and that requires vast areas bathed in sunshine. It's all about area covered and conversion efficiency.
Consider: the algae-equivalent of the current 85 million barrels-per-day petroleum consumption worldwide would require 650 million acres covered in water, even with highly efficient production. If only one foot deep, the ponds would require 650 million acre-feet of water. And that does not begin to consider the energy required to merely pump that volume of water!
Some hold out hope that salty water can be used to grow algae. However, the water quality of even salty water must be proper to efficiently grow algae, and logistics will inevitably dominate the entire process.
In many ways, it seems that, while high-tech, genetically-engineered systems might be better suited for fully enclosed spaces, the practical dimension of occupying such gigantic areas and enclosing genetically modified organisms may present some untoward consequences.
While successful demonstrations have shown algae fat can be converted into jet fuel, only careful testing, research and analysis will determine if fat algae are a practical, sustainable energy source.
Coffey is an attorney based in San Diego. He can be reached at firstname.lastname@example.org. Comments may be published as Letters to the Editor.