A new analysis from Argonne National Laboratory, funded by the U.S. Department of Energy’s Bioenergy Technologies Office (BETO), shows the potential of an algae fractionation process to produce renewable diesel fuel with 63%–68% lower greenhouse gas (GHG) emissions than conventional diesel. The peer-reviewed journal Algal Research published this analysis.

In some algal biofuel production methods, lipids are extracted from algae and converted to renewable diesel, while the non-lipid components of the algae are converted to biogas. The biogas is used for renewable heat and electricity to power the conversion process of the lipids to renewable diesel. 

In the algae fractionation process, however, the carbohydrates in the algae’s non-lipid components are converted to ethanol instead of biogas. The process produces two fuels—renewable diesel and ethanol—from the same algae. The increased fuel outputs can lower the cost of the biofuels. However, without the biogas to power the process, algae fractionation requires more energy. 

Scientists used life-cycle analysis to analyze whether the energy required for this process would still result in lower GHG emissions relative to conventional fuel. Their analysis showed lower GHG emissions from algae fractionation than those associated with conventional low-sulfur petroleum diesel—showing that the biofuel pathway could still reduce GHG emissions compared to petroleum fuels that are used today.

Life-cycle analysis of different biofuel conversion routes is important to finding biofuel pathways that help mitigate climate change and meet the low GHG emissions thresholds established in the Renewable Fuel Standard. Many life-cycle analyses conducted by companies are proprietary; however, this life-cycle analysis is publicly available because it was conducted with federal funding. 

This project is part of BETO’s Strategic Analysis and Sustainability Program, which conducts research and analysis to understand and enhance the environmental, social, and economic benefits of bioenergy production while mitigating concerns. BETO also conducts research, development, and demonstration projects to lower the cost of algal biofuel production. These efforts are critical to achieving BETO’s overall goals to develop sustainable, commercially viable biofuels.