NRG Energy and GreenFuel Technologies Corp have begun field testing an emissions-to-biofuel technology at NRG's Big Cajun II, 1,489 MW coal-fired power plant in New Roads, Louisiana.
GreenFuel’s proprietory process uses algae to capture flue gas carbon dioxide with the energy-rich algae harvested daily. This algae can then be converted into a broad range of biofuels for use as a renewable fuel for the power plant or elsewhere or used for animal feed supplements.
According to a statement from the company, the process requires no re-engineering of the power plant.
In the initial field testing, which will last approximately four months, algae species will be selected to optimise biofuel production based on the site’s flue gas composition, local climate and geography toward an ultimate goal of construction of a commercial-scale facility.
The process uses photosynthesis to grow algae, capture CO2 and produce high-energy biomass, serving as a flexible platform for retrofitting fossil-fired power plants and other anthropogenic sources of carbon dioxide using commercially available technology. Flue gas or other CO2-rich gas streams are introduced to the bioreactor, in which algae are suspended in a media with nutrients added to optimise the growth rate. A portion of the media is withdrawn continuously from the bioreactor and sent to a two stage dewatering process to harvest the algae while a blower pulls the flue gas through the bioreactor. Using an induced draft fan provides several operating advantages, including ensuring minimal disruption to power plant operations, simplifying retrofits to existing facilities. A full scale commercial deployment could recycle enough carbon dioxide to yield some 37,000 litres of biodiesel per acre annually, the company says.