Biofuels are a promising source of achieving energy security, economic development, and climate change mitigation/pollution control solutions.
Algae as a source of biofuels possess certain advantages compared to other sources of oil such as soybean, sunflower and palm oil. Microalgae specifically provide much higher yield of biomass, they reproduce and photosynthesize fast. Algae can be grown on land unsuitable for conventional crop so they do not compete for land with crop plants, they can also use water sources unsuitable for other crops such as seawater, wastewater and brackish water. They need carbon dioxide (CO2) as they grow like any other plant but for high productivity algae needs more CO2, which can be supplied by emission sources such as power plant.
A great amount of research is being done to make algal biofuel production more efficient and less expensive. NASA’s Offshore Membrane Enclosure for Growing algae (OMEGA) is a system developed to grow algae by using wastewater and CO2 using photo bioreactors, which are flexible plastic tubes floating in sea water. These plastic photo bioreactors (PBRs) are attached to a floating infrastructure anchored offshore in a protected bay. The system make use of wastewater which is pumped offshore without affecting the urban infrastructure. Wastewater and CO2 from coastal facilities provide water and nutrients. The surrounding seawater controls the temperature inside the PBRs and kills algae that escape from the system. The salt gradient between seawater and wastewater drives forward osmosis, to concentrate nutrients and facilitate algae harvesting. The OMEGA infrastructure also supports aquaculture below the surface and provides surfaces for solar panels and access to offshore wave generators and wind turbines.
An integrated OMEGA system is an ecology of technologies that produces biofuels, treats wastewater, produces renewable electricity and supports aquaculture.
With support from the California Energy Commission (CEC) and NASA, a team of scientists and engineers developed and tested the OMEGA system in seawater tanks. The California Energy Commission issued a report providing the results of feasibility study of OMEGA system.
OMEGA has passed the planning and testing, the system is ready for deployment. The results confirm that OMEGA is feasible for growing microalgae on wastewater using photo bioreactors and suggest at least in coastal cities the system could be an alternative way to produce biofuels.