Algae turns waste into fuel

Worried about the scarcity of fossil fuels? Researchers at Mountain View’s NASA Ames say they have a solution.

On Tuesday, NASA Ames scientist Jonathan Trent showed the world what he’s been working on at a San Francisco wastewater treatment plant. He is lead scientist for OMEGA, or Offshore Membrane Enclosure for Growing Algae. It turns out that the same algae that was once buried millions of years ago and produced most of our fossil fuel deposits can be grown to produce vegetable oil at rates much higher than soil crops. That oil can then be turned into diesel fuel and jet fuel.

The fruit of OMEGA’s labor is a floating “photobioreactor” system — “micro-algae” growing inside special flexible and transparent plastic membranes suspended in saltwater as the algae feasts on treated sewage.

Trent says that someday the country’s entire aviation industry could be powered by 10 million acres of oceanic algae farms producing biofuel.

Floating algae farm

On Tuesday researchers introduced the idea of a 1200-acre algae farm floating in the San Francisco Bay to help treat 85 million gallons of wastewater every day leaving the wastewater plant at 750 Phelps St. Trent said such an operation would provide 6,500 gallons of vegetable oil a day, “not a huge amount of oil for a city San Francisco’s size, although it would contribute significantly” to fuel demands.

NASA, which funded OMEGA with $10 million two years ago, is interested in biofuel to meet demand for aircraft and maybe even spacecraft. Trent said most vehicles on the ground will likely be able to use electricity, but powering aircraft is more difficult.

To supply the 20 billion gallons of jet fuel used by the country’s planes every year would require a piece of the ocean 125 miles long and 125 miles wide. Such an amount would probably be dispersed in ocean waters near major city sewage plants, Trent said.

Such an operation could affect boating and fishing in the bay, Trent said, but would otherwise pose no threat to the environment, and would in fact help reduce carbon in the atmosphere and remove elements from wastewater that create “deadzones” in the ocean. Trent said the algae enclosures were even tested with the help of sea lions and sea otters that were trained to bite and jump on the flexible plastic membranes. Trent said any damage to the membranes would result in leakage of biodegradable treated sewage, and the freshwater algae would die in the saltwater instead of becoming an invasive species.

Prototypes at work

At San Francisco’s Southeast Water Pollution Control Plant, the OMEGA team has set up a lab in a trailer, built greenhouses for growing algae and took over a large cement tank once used for traditional sewage treatment. It is now filled with saltwater pumped in from nearby Islais Creek. Several different prototype plastic enclosures float in the tank, some of which were abandoned for better designs. Trent describes the various parts using analogies to the human body. The “heart” is a pump that pushes the wastewater into the photobioreactors, which are analogous to a “digestive system.” Then there’s the “lungs” which make sure the algae have the right amount of carbon dioxide and not too much oxygen.

The algae can produce 5,000 gallons of oil per acre every year, which is much more than the 600 gallons a year produced by the best biofuel crops grown on land.

It’s an important point that algae farming “would not compete with agriculture because the algae would not use the water, fertilizer or land,” Trent said. A criticism of biofuel production is food shortages affecting millions of people because of farmland being devoted to biofuel crops.

It’s possible the algae could be grown on fallow desert land, but Trent said the cost of bringing water to such farms would make it less worthwhile economically. Being able to treat wastewater with such a system is also a major contributor to potential financial viability.

Trent acknowledges that micro-algae will never be able to compete with oil supplies in the earth, as long as one oil well can produce 144,000 gallons a year. But when that oil dries up, or before then, he says NASA is willing to contribute its knowledge from the “open source” project to commercial companies.

There’s no word yet on whether an investors have stepped up to fund such an algae farm in San Francisco Bay. When asked if there were investors, OMEGA project manager Steven Ord said, “The idea is to get the word out so people can take the next step.”