|A prototype of the Solix photo-bioreactor for algae production. Click to enlarge.|
Solix Biofuels Inc., a startup company based in Boulder, Colorado, is working with Colorado State University engineers to commercialize technology to produce biodiesel from oil derived from algae. Solix officials plan to have the technology on the market over the next two years.
The Solix photo-bioreactors for algae production are based upon 20 years of research (the Aquatic Species Program) originating at the National Renewal Energy Laboratory (NREL), and are massively scaleable, according to the company.
The algae grow within closed plastic bags, which reduces the possibility of infestation drastically. A novel low-energy temperature control system keeps the algae within a temperature range that optimizes growth.
The bioreactor primarily consists of two large transparent flattened tubes made of specialty plastics. Water-weighted rollers squeeze the algae-bearing fluid through the tubes as they slowly move down tracks built into concrete supports on the side of the tubes.
The peristaltic motion of the rollers creates a current inside the reactor, which force the algae to be in constant motion and allows more than just the top layer of algae to receive sunlight.
In turn, that allows the fluid depth of the reactor to be 12 inches, and thus does not restrict photosynthesis to the surface layer of the fluid—a traditional obstacle to making cost-efficient photosynthetic bioreactors.
Within the “bag” is a thermal layer that can be raised or lowered by the rollers to regulate the internal temperature of the bioreactor. The shape of the straps holding the foam is designed to maximize the fluid rotation within the reactor, presenting all the algae sequentially to the sun absorption zone in the top layers of the reactor. CO2 is injected into the photo-bioreactor for the photosynthesis reaction.
Colorado State and Solix officials are collaborating with New Belgium Brewing Co. to use excess carbon dioxide from the brewery’s plant to test the algae-based biodiesel process.
Algae cells are harvested from the fluid with a centrifuge. Once harvested, the oil will be extracted and the resulting oil can then be refined into biodiesel fuels through the same transesterification process currently used to refine other vegetative oil sources into biodiesel. The algae oil can also be refined into other liquid fuels, including ethanol and jet fuel.
Solix officials estimate that widespread construction of its photo-bioreactor system could meet the demand for the US consumption of diesel fuel—about 4 million barrels a day—by growing algae on less than 0.5% of the US land area, which is otherwise unused land adjacent to power plants and ethanol plants. The plants would also supply the requisite carbon dioxide.
Algae to biofuel technologies are still being developed, yet a strong case can be made for global domestication of algae as an energy crop. We want to manage this technology to create a business that will serve current and future energy stakeholders.—Doug Henston, chief executive officer of Solix