CSU Researchers Say Algal Biodiesel Net Energy Ratio Better than Soy

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Researchers at Colorado State University state that a detailed engineering model for one algal species -- Nannochloropsis -- in a photobioreactor model using current technology will show the superiority of algal biodiesel over soy biodiesel in terms of net energy ratios and greenhouse gases.

Their analysis of this process and organism found the Net Energy Ratio (MJ consumed·(MJ produced)-1) for microalage biodiesel to be 0.93; for soybean biodiesel to be 1.64; and for petroleum diesel to be 0.19.

Although the energy required to support the growth stage during microalgae cultivation is 2.1 times higher than the energy required to support soy growth, they found that microalgae extraction uses less energy than soy oil extraction.

The primary energetic advantage of the microalgae process, relative to soy, is related to the energy embedded in the feedstock. Soybeans contain 18% lipid by dry weight, whereas Nannochloropsis salina contains 50%. This means that less microalgae is required to produce 1 unit of biofuel energy than is required of soybeans.
—Batan et al.

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Soy is a very efficient food crop, with an excellent protein profile. But it will not be able to compete with more efficient oil crops such as micro-algae as the agro-industrial processes to produce fuel from algae is developed.

Initially, a more economical and efficient way of producing fuel from algae would utilise fast-growing, low oil species of algae for their biomass. As Craig Venter and other synthetic biologists develop better species of algae as oil crops, and as industrial engineers design better ways to extract the oil, the oil-to-fuels (and chemicals) approach is likely to edge out the algal biomass approach for most applications.