Start-up enlists algae for toxic clean-up, fuel

Algae may one day be the preferred feedstock for biofuels. But in the meantime, it can have a job cleaning up waste water.

Seattle-area start-up Bionavitas is one of several companies moving into the algae business. Because it doesn't compete with food and has a high energy density, algae has a lot of potential as a source of biodiesel.

Plastic bags house algae at GreenFuel Technologies test facility at an Arizona power plant.

(Credit: GreenFuel Technologies)

But it will take years before algae biodiesel will make a dent in the petroleum diesel market, said Bionavitas CEO and co-founder Michael Weaver.

So in the short term, the company is growing algae for alternative markets: oils for pharmaceuticals and waste water treatment.

"One of the most promising markets is water remediation for mining--taking a lot of leeching elements out of water sources passing nearby," said Weaver. "Certain strains of algae suck (pollutants) into them."

He said the company has been able to take selenium out of a water source, which can be a poisonous byproduct of agricultural operations.

Once the algae is grown, the idea is to process it for oil for biodiesel or to dry it to be burned as fuel.

Self shading and passive optics
Bionavitas is developing bioreactors that Weaver says will be able to be deployed on a large scale, which would allow a low-cost manufacturing approach to algae farming.

A tube from PetroAlgae, which is developing algae bioreactors for biodiesel.

(Credit: PetroAlgae)

Although algae has advantages over soy as a feedstock, production of biodiesel has to be very inexpensive to compete with other diesel fuels. Algae can be grown relatively easily but it remains largely experimental because nobody has been able to produce it at commercial scale cheaply.

Weaver was cagey about what its bioreactors will look like. But he said that the main problem that Bionavitas is attacking is self shading.

That is, once algae grow to a certain thickness in tubes or plastic bags, the amount of light decreases, slowing down growth.

"Self shading is a real issue in the expense," Weaver said. "We're developing a passive optical system that will allow light to penetrate the first few centimeters of algae growth."

He said that the company won't be using mirrors or solar collectors because they are too expensive.

The company is self-funded and is starting to look for a Series A venture capital round.

"The industry is probably a good three or four years from mass production of biodiesel," Weaver said. "We're closer on bioremediation; we're able to do that now."