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Algae feed off wastewater and carbon dioxide to produce biomass for fuel, fertiliser and feed in floating 'photobioreactors'.
NASA has developed a unique coastal floating system to produce biomass suitable for biofuels, fertiliser and animal feed, without competing with agriculture for water or land. Its Offshore Membrane Enclosures for Growing Algae [OMEGA] project converts wastewater and carbon dioxide into oxygen and biomass, through the cultivation of freshwater algae.
The rapid-growing algae feed off wastewater and draw on energy from the sun in large floating tubes of plastic, called ‘photobioreactors’, which are moored off the coastline. The algae remove pollutants from the wastewater, while the sea itself provides natural cooling, to prevent the organic system from overheating. The photobioreactors also offer new habitats for marine life.
A 450-gallon prototype has been trialled at the San Francisco Public Utilities Commission’s Southeast Water Pollution Control Plant, following small-scale tests of the principle in seawater tanks at the California Fish and Game laboratory in Santa Cruz. The team is now exploring the feasibility of large-scale applications.
“We’ve addressed some of the more daunting technological problems for implementing OMEGA,” says Jonathan Trent, the NASA bioengineer leading the OMEGA project. One of the main challenges was removing the oxygen, a by-product, from the system and introducing more carbon dioxide, to prevent the algae from becoming starved. The tubular solution introduces CO2 with wastewater at the bottom of the containers, and allows O2 to escape through the walls of the photobioreactors. Trent says that the OMEGA system can also be connected with renewable energy infrastructure, such as wind or wave, to improve its financial viability.
Earlier this year, NASA invited members of the biofuel industry to develop the OMEGA concept. “Now the hope is that other organizations and industries will realise the potential of the OMEGA technology for wastewater treatment and ultimately to produce sustainable biofuels.”
NASA originally launched the OMEGA project to investigate its potential to produce fuel for aviation.
“The development of sustainable biofuels is crucial for the world, where we are almost entirely dependent on fossil fuel for transportation”, says Martin Tangney, the Director of the Biofuel Research Centre at the Edinburgh Napier University. “This NASA initiative has tremendous potential, but the key will be maintaining an environmental balance with financial viability, as ultimately all biofuel must compete on the open fuel market.” – Ian Randall
Photo: NASA Ames Research Center