Microalgae Biofixation of CO2 and Fertilizer Production for Greenhouse Gas Abatement

75974-Microalgae biofixation is a candidate technology for abating the emissions of greenhouse gases, particularly CO2, while simultaneously producing biofuels (for electricity generation) and nitrogen fertilizers. One approach is to use nitrogen-fixing microalgae, cultivated in large open ponds and harvested to produce both renewable fuels (methane) and organic nitrogen fertilizers. However, a major issue is productivity, measured in tons of fertilizers and biofuels that can be produced per acre (hectare) of ponds per year. In this project, cultures of nitrogen-fixing cyanobacteria (a form of microalgae) will be cultivated in ponds containing freshwater or seawater, and the harvested algal biomass will be digested to generate methane gas and a liquid organic fertilizer suitable for crop production. Productivity will be maximized by selecting high productivity strains and by developing mutants with reduced light harvesting pigments. Phase I will operate four small (3 m2) outdoor ponds for culturing the N2-fixing cyanobacteria and determine the ability of such cultures to produce sufficient biomass for anaerobic digestion that generates methane fuel and organic fertilizer. Commercial Applications and Other Benefits as described by the awardee: Microalgae CO2 biofixation processes for the combined production of biofuels and nitrogen fertilizers would not only reduce CO2 emissions, but also provide benefits to the agriculture industry and reduce U.S. dependence on imported oil.