Pond Scum – the New Texas Tea

The energy business is getting more interesting. Chevron, Honeywell, and Boeing have all announced projects to grow algae for use as substitutes for petroleum based energy products. Now PetroSun has started a commercial farm operation on the Texas Gulf Coast near Harlingen to grow it for conversion into diesel and jet fuel. Scientists have been saying for years that algae has the potential to replace the world’s consumption of petroleum, all of it, but until recently nobody has found a cost effective way to solve the technical problems. PetroSun thinks it has one. If they are right it will be the biggest economic news since the invention of the internal combustion engine. The stuff has a lot of advantages. It is an inexhaustible renewable resource. It’s eminently biodegradable. It doesn’t need arable land. Certain strains thrive in brackish or salty water. Under ideal conditions it is many times more productive than any other crop. Enough of it could be grown on a few square miles of desert to supply all of America’s energy needs. It could turn America into a net energy exporter. It can be fed with animal or vegetable waste, including municipal waste. It’s a potential use for the excess carbon dioxide being spewed out by power and cement pants. Biodiesel fuel can be burned efficiently in existing engines and delivered through existing infrastructure. It contains no sulfur. What’s left over after extracting vegetable oil for use as fuel can make a nutritious food supplement for animals or humans. A group of engineers at Auburn University has calculated that Alabama’s cattle and chicken farms alone produce more than enough waste to satisfy the state’s need for liquid fuel. They’ve developed a design they think is feasible for doing just that, and at a profit. The seminal work on algae based fuels came out of the Department of Energy’s Aquatic Species Program a relatively small research project launched in 1978 in the wake of the Arab Oil Embargo. ASP demonstrated conclusively that oils from algae can produce natural gas and just about anything petroleum can but they never could make the numbers work. In 1996, with gasoline at $1 a gallon, DOE shut it down. The technical problems were serious. ASP focused on open pond systems thinking that an enclosed system would be too expensive. A lot of people thought that was a mistake, though both the PetroSun farm and the Auburn system are based on open pond designs. The open pond left them vulnerable to the vagaries of weather and contamination. This works best with a pure strain of algae suited for the specific purpose. One strain is right for diesel, another for jet fuel, a third for methane. Maximum yields require ideal conditions of light, temperature, and nutrient and catalyst levels. The algae must be circulated at just the right rate to avoid under or over exposure to sunlight. You need a lot more carbon dioxide than can be squeezed from the air. You have to get it from somewhere and it has to be mixed with water. At harvest time the algae must be extracted from the water, and the oil from the algae. ASP overcame all of those issues but their costs were just too high. Fortunately research continued in the private sector and today, with oil at over $100 per barrel, the economics look a lot better. So does the technology. There are pilot projects going on at several places around the country using enclosed bioreactors that may be more costly than the ponds but are also more efficient and easier to control. When smokestack and vehicular carbon dioxide sequestering technology becomes commercially viable we may see an explosion of algae farms recycling it back into reusable energy. In the meantime it looks like we may well be on the way to not needing it.