The Promise of Blue-green Algae: An Environmentally Friendly Source for Producing Biofuels and Other Products

An Algenol-Georgia Tech team that includes ISyE Anderson Interface Professor of Natural Systems Valerie Thomas is working to produce ethanol from cyanobacteria. 

Many people are familiar with ethanol — a popular biofuel mixed with gasoline — and how it’s made in the United States: from corn. Second-generation biofuel is also coming on to the market, made from inedible plant materials such as corn stalks, leaves, and cobs.

Now, thanks to a $6.25 million grant from the U.S. Department of Energy (DOE), a third generation of biofuel is being developed via blue-green algae, or cyanobacteria.

The three-year grant was jointly awarded to Algenol, an industrial biotechnology company; Georgia Tech; the National Renewable Energy Laboratory; and Reliance Industries under the DOE’s Advancements in Algal Biomass Yield, Phase 2 (ABY2) program to produce biocrude and co-products. Valerie Thomas, the Stewart School of Industrial & Systems Engineering’s Anderson Interface Professor of Natural Systems, and Matthew Realff, the School of Chemical & Biomolecular Engineering’s Professor and David Wang Sr. Fellow, are the lead researchers from Georgia Tech.

This grant will enable the team to explore the environmental process and impacts of cyanobacteria-produced biofuels and other high-value chemicals. The ethanol is extracted from the algae’s water and nutrient bath in a process that is similar to whiskey distillation. Algenol has developed a process that produces pure ethanol from very dilute ethanol in a way that is highly energy efficient.

Why is cyanobacteria as a source for ethanol so promising? Principally, cyanobacteria-produced biofuel is environmentally friendly — for a number of reasons.

As Thomas explained, “The algae are grown in photobioreactors, which are basically large plastic bags, along with water and nutrients. The plastic bags hang in rows out in the sun, and there’s no reason for the land to be good agricultural land. It can be in desert areas or near the coast for shipping. It’s also quite productive per acre compared with land plants [that can be used to make first- or second-generation biofuel].”

In addition, the carbon dioxide that the algae need to grow could be siphoned-off fossil fuel power plant emissions and piped into the photobioreactors. A number of other carbon capture and utilization scenarios for biorefineries have been studied by the Algenol-Georgia Tech team, including stand-alone systems where carbon dioxide is generated on-site. Many of those scenarios show competitive economics and very low carbon footprints compared to gasoline.

Thomas — an expert on greenhouse gas emission evaluation — and Realff — an expert in chemical process modeling and optimization — have been working with Algenol on its biofuel production processes for a number of years. Thomas works in environmental systems analysis, with a main area being life-cycle assessment. This means that she looks at the entire supply chain for producing and using this biofuel. She said that this includes “what kind of fertilizer it uses, how the production facility is built, and the energy used in the facility — how much is used and where it comes from. All the emissions need to be taken into account.”

To proceed to commercial-scale production, the process needs to be both environmentally sound and cost-effective. It’s challenging to make third-generation biofuel that can match today’s historically low petroleum prices. However, Algenol technology can yield other products, including natural food colorants and fertilizers, that are well along in the pipeline.

Expanding on the multi-product approach, the grant team is evaluating additional biofuel components that can be made within an Algenol biorefinery that would be cost-effective and have low environmental impact.