Could the future of algae-based compounds be blue-green?

Researchers at the U.S. Department of Energy’s (DOE) National Renewable Energy Laboratory (NREL) might say yes. A team led by Principal Investigator Jianping Yu has made significant progress toward crafting an advanced strain of cyanobacteria that could redefine the future of algal biofuel production.  

Cyanobacteria, also known as blue-green algae, are naturally occurring organisms that use photosynthesis to convert carbon dioxide to biomass for energy. The strain developed by NREL can use a similar process to convert carbon dioxide into ethylenea valuable organic compound that is used to produce polymers, chemicals, and liquid transportation fuels. With so many uses, ethylene is the most widely produced petrochemical feedstock in the world. It is traditionally produced from fossil fuels through a steam cracking process, which results in significant carbon dioxide outputroughly 1.5–3 tons of carbon dioxide per every ton of ethylene that is made. In contrast, the cyanobacteria absorb carbon dioxide from a neighboring power plant or other high-concentration source and use it to create ethylene. According to NREL, this could potentially save 6 tons of carbon dioxide emissions for every ton of ethylene produced. This noticeable reduction in greenhouse gas emissions makes the produced bio-ethylene an attractive, invaluable alternative to petroleum and traditional ethylene.

Cyanobacteria

Principal Investigator Jianping Yu and Post-Doc Justin Ungerer work with the cyanobacteria strain in a photobioreactor. (Photo courtesy of Lynn Westdal, NREL)

Funding for this critical research was provided through DOE's Bioenergy Technologies Office as a seed project for fiscal year 20112012. NREL is engaging in additional research and testing on the advanced strain of cyanobacteria to expand its potential even further—modified versions could see an increase in the amount of ethylene produced and a greater level of carbon dioxide consumption. The ethylene created leaves the organism naturally, making it easy and inexpensive to collect while simultaneously encouraging the bacteria to continue its production. To date, the strain has been grown in shake flasks containing sea water and in a laboratory-scale photobioreactor. However, there is potential for scale-up in brackish, waste, and sea water, which would further improve its appeal in the bioenergy industry. More importantly, the potential yield of biofuels from this strain—through eventual conversion of bio-ethylene—is higher than the yield for many other energy crops, including land-based feedstock and other algae. This is a result of the high photosynthetic activity level that is common of cyanobacteria. 

NREL is currently in discussions with potential technology partners to move the strain to an industrial-scale or demonstration-scale application. Through its intensive research on cyanobacteria, NREL is laying the foundation for a sustainable, profitable future in blue-green algae biofuels.