APS Emissions to BioFuels Project
APS is currently conducting an exciting demonstration project of GreenFuel Technology that produces biofuel from algae grown from power plant emissions. This project won the Emissions Energy Project of the Year award for 2006 at the 8th Annual Platts Global Energy Awards in New York.

The APS demonstration is based upon technology first implemented using emissions from the physical plant on the campus at MIT and based on an MIT scientist’s work for NASA. The purpose of the demonstration is to determine the feasibility of a commercial process. The APS demonstration adapts the processes developed in Boston, by GreenFuel Technologies, to the Arizona climate, and seeks to determine the effectiveness of algae to photosynthetically convert flue gas carbon dioxide into fuel.  

How it works
Emission flue gas from the Company’s Redhawk Power Plant stack is piped to biosolar reactors containing select natural algae. Since the algae consume carbon dioxide in the presence of sunlight (photosynthesis), the goal is to recycle carbon in an economical manner by periodically harvesting and processing the algae into biodiesel fuel, which can be used in place of diesel fuel in applications such as our line trucks. In addition, starches from the algae can be turned into ethanol, and the remaining protein into a high-grade food for livestock, or returned to the algae farm as nutrient. Nothing goes to waste.

If the project demonstrates economical potential, the algae also could be gasified and fed back into the combustion turbines at Redhawk, reducing fuel demand. Or, in the case of a coal plant, it could just be mixed in with the coal without any fuel preparation. This process may lead to an economical reduction of APS’ CO₂ footprint.  

The first phase of this project has been successfully completed with the selection of an algae strain that not only survived the torrid Arizona summer, but was able to show almost 10,000 Btu/lbs. of energy content. During this first phase, CO₂ reduction was approximately 80 percent during daylight hours and the reproduction of the algae was such that a one-acre bioreactor system can be projected to produce 6,000 gallons of biodiesel fuel per year plus 5,000 gallons of ethanol. This represents significantly more “fuel per acre” compared to other “fuel” crops.

The second phase of the program has now begun, involving the construction and operation of a one-third acre bioreactor system at the Redhawk Power Plant. Location of a bioreactor system at a pulverized coal plant is also underway with a site selection process at the APS Four Corners Plant in New Mexico.