In our last FastForward Radio show Phil and I discussed the possibility of oceanic plankton being used to sequester the greenhouse gas carbon dioxide. As an aside I mentioned that plankton makes a good bio-diesel. In other words, we could get a twofer out of the deal. We sequester carbon AND we harvest some of the plankton for energy.
It’s not a bad idea, but ramping up a major offshore project with unproven technology would be difficult. Fortunately there is an easier way to get started. Last week The New York Times published an article about a related venture:
A few companies are in a race to be first to convert [freshwater] algae to fuel on a commercial scale, and it will require not a small amount of money, luck and biotech tweaking…
[The goal] is to find an energy-efficient way to convert algae into fuel [pdf link], which is why she [Venture Capitalist Lissa Morgenthaler-Jones] was visiting a catfish farm here that was for sale. Farmed catfish could provide a useful source of carbon dioxide for the algae, as well as a critical revenue flow to keep research going…
By comparison to plankton, algae is lower hanging bio-diesel. Working onshore would eliminate much risk – to people and to the project. And lessons learned could further offshore plankton projects later.
According to the US Department of Energy, algae can produce more bio-diesel than any other plant. Algae doesn’t have to waste energy drawing water and nutrients from the ground. Algae’s advantage is that it is suspended in the aqueous solution of the carbon dioxide and nutrients it needs to grow.
Using catfish as a source of CO2 helps in a small-scale experimental pond, but commercial algae production would not be huge catfish farms. On larger scales catfish would be more of a distraction than a revenue source. Scientists are recommending using the desert:
Geothermal activity under the desert could provide a free source of carbon dioxide to bubble up for the algae to absorb and convert into organic matter to process as fuel…
“If the U.S. put 15 million acres of desert into algae production, we could produce enough volume of liquid fuels to get us off the Middle East oil addiction and give Iowa back to the songbirds,” said B. Gregory Mitchell, an algae research biologist at the University of California , San Diego, who is a friend of Ms. Morgenthaler-Jones and Mr. Jones.
Gregory Mitchell’s calculation is based on a theoretical production of 20,000 gallons of bio-diesel per year per acre of algae.
One requirement that would be in short supply in the desert is water. It would have to be piped in from elsewhere. Perhaps algae wouldn’t require potable water. Runoff water and even sewage from desert cities like Las Vegas and Phoenix might be usable. Such water would have to be treated because algae ponds are subject to contamination which would reduce bio-diesel yields.
Obviously there is much work to be done. But if we can do this we would be harnessing desert solar power and CO2 for our energy needs.
