Low-Cost Polymer Flocculant for Algae Production

Microalgae are unicellular microorganisms that can produce up to 60% of their mass in vegetable oil. They are cultivated in water, consume CO2, and are 50 times more productive than oilseed crops for producing oil on a per acre basis. The lipids they produce can be converted into biofuels such as biodiesel and renewable diesel, which can be combusted in a standard diesel engine. However, the algae in the water are dilute, and current techniques for concentrating algae biomass significantly increase the cost of the biofuel. What is needed is a new, low-cost polymer flocculent that can effectively concentrate the algae cells into large agglomerates. The Phase I project will synthesize novel low-cost polymer flocculants that are tailored to the algae strains that are grown for large-scale biofuels production. The polymer flocculants will be tested for their ability to coagulate dilute algae cells into large agglomerates, which would be easier to concentrate via simple low-energy separation methods such as gravity settling and screening. The project will include a detailed engineering and economic analysis for using the polymer flocculants to harvest algae for biofuels. Commercial Applications and other Benefits as described by the awardee: New, low-cost polymer flocculants for harvesting algae cells in large-scale cultivations would permit the U.S. biodiesel industry to grow well beyond its capacity, which now is based on the use of refined vegetable oils from soy and canola. An expanded use of biodiesel would reduce CO2 emissions by 80% compared to petroleum diesel and reduce our nation¿s dependence on foreign oil, while promoting economic opportunities in rural America.