Florida startup Algenol Biofuels says that it can efficiently produce commercial quantities of ethanol directly from algae without the need for fresh water or agricultural lands–a novel approach that has captured the interest and backing of Dow Chemical, the chemical giant based in Midland, MI.
The companies recently announced plans to build and operate a demonstration plant on 24 acres of property at Dow’s sprawling Freeport, TX, manufacturing site. The plant will consist of 3,100 horizontal bioreactors, each about 5 feet wide and 50 feet long and capable of holding 4,000 liters.
The bioreactors are essentially troughs covered by a dome of semitransparent film and filled with salt water that has been pumped in from the ocean. The photosynthetic algae growing inside are exposed to sunlight and fed a stream of carbon dioxide from Dow’s chemical production units. The goal is to produce 100,000 gallons of ethanol annually.
There are dozens of companies in the market trying to produce biofuels from algae, but most to date have focused on growing and harvesting the microorganisms to extract their oil, and then refining that oil into biodiesel or jet fuel. Instead, Algenol has chosen to genetically enhance certain strains of blue-green algae, also known as cyanobacteria, to convert as much carbon dioxide as possible into ethanol using a process that doesn’t require harvesting to collect the fuel.
Blue-green algae do produce small amounts of ethanol naturally, but only under anaerobic conditions when the cyanobacteria are starved or in the dark. Paul Woods, cofounder and chief executive of Algenol, says that his company has modified its algae so that it can produce ethanol under sunlight through photosynthesis, first by turning carbon dioxide and water into sugars, then by boosting and controlling the enzymes that synthesize those sugars into ethanol.
Another big difference for Algenol is that it doesn’t have to harvest its algae to extract the ethanol, eliminating a step that has proved costly and complex for other algae-to-biofuel startups. John Coleman, chief scientific officer at Algenol and a professor of cell and system biology at the University of Toronto, says that the ethanol produced within the algae will seep out of each cell and evaporate into the headspace of the bioreactor.