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APS is conducting an exciting demonstration project in conjunction with GreenFuel Technology that uses carbon dioxide from power plant emissions to grow algae which is then used to produce biofuels. This addresses two important issues in the U.S. today; reducing greenhouse gases from power plants and producing more domestic sources of alternative fuels for cars and power plants. This project started at our Redhawk natural gas power plant, and in 2007 was expanded to our Four Corners coal fired power plant.
 How it works
Emission flue gas from the 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.
During the first phase of the project, tests showed that the algae was able to product almost 10,000 Btu/lbs of energy content. CO2 reduction was approximately 80 percent during the 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 per year plus 5,000 gallons of ethanol. This represents signficiantly more "fuel per acre" compared to other "fuel" crops. Further testing In 2007 by GreenFuel Technology at the Redhawk plant showed promise for high CO2 capture rates per acre. In 2007, biodiesel produced from algae grown in Redhawk plant emissions was submitted to the National Energy Technology Lab for testing and the results will be incorporated into the final evaluation of the project.
In addition, tests at the Four Corners plant showed that algae actually grew faster in the 4-Corners flue gas than in pure CO2. This demonstration project will continue at both of these plants through 2008.
The company’s emissions-to-biofuels project at the Redhawk Power Plant was featured in an October 2007 National Geographic cover story about how plants are being developed into fuel.
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