Arizona Public Service Company (APS) and its partner GreenFuel Technologies are to attempt to replicate their success of creating biofuels from algae grown using carbon dioxide (CO2) emissions from a power plant. This time, however, instead of using CO2 from a natural gas power plant, they will use emissions from a coal-burning power plant.

The move comes after the companies were able to successfully grow algae, this summer, at APS’ Redhawk natural gas power plant at levels 37 times higher than corn and 140 times higher than soybeans.

“At this productivity level, GreenFuel’s system is ahead of other biomass production methods,”  said Professor Otto Pulz, president of the European Society of Microalgal Biotechnology and head of the IGV Institute’s Biotechnology Department in Germany.

The growth rate — an average productivity of 98 grams/meter2/day (ash free, dry weight basis) and reaching a high peak value of 174 grams/meter2/day — surpassed previous lab growth rates and exceeded all expectations going into the project. The results provide evidence of the financial viability of using the emissions of a power plant to grow algae for the exclusive purpose of creating biofuels.

The project is now moving to APS’ Four Corners Generation station, a coal power plant located in Farmington, N.M.

“It is now time to see if we can replicate this success at Four Corners,” said Ray Hobbs, manager of the APS Future Fuels Program. “This project addresses two important issues in the U.S. today — reducing greenhouse gas emissions at power plants and producing more domestic sources of alternative fuels for automobiles and power plants.”

GreenFuel’s Emissions-to-Biofuels™ technology uses safe, naturally occurring algae to recycle CO2 from the stack gases of power plants and other commercial sources of continuous CO2 emissions. At the Redhawk Power Plant, specially designed pipes captured and transported the CO2 emissions from the stack to specialized containers holding algae. In the presence of sunlight, the algae consumed CO2.

Moving to a coal plant is the next progression in this evolving technology. The Department of Energy’s National Energy Technology Laboratory (NETL) has been providing technical assistance throughout the process.