Energy Management

Two solar augmentation projects target natural gas and coal generation


Feb 13, 2009

The Electric Power Research Institute (EPRI) has launched the second of two projects to help electric power companies add solar energy to fossil-fueled electric power plants, reducing fuel costs and plant emissions. Tri-State Generation & Transmission Association Inc. and Progress Energy and Southern Co. are participating in the project. The case study analyses will be performed by WorleyParsons Group Inc.

Both this project and a parallel study launched in October 2008 at natural gas-fueled facilities involve adding steam generated by a solar thermal field to a conventional fossil fuel-powered steam cycle to offset some of the fuel required to generate electric power. As part of the coal project, case studies will be conducted at Tri-State’s 245-megawatt (MW) Escalante Generating Station in Prewitt, N.M., and at Progress Energy’s 742-MW Mayo Plant in Roxboro, N.C.

“These projects will demonstrate a near-term and cost-effective way to use large amounts of solar energy at commercial scale to provide clean electric power,” said Dr. Bryan Hannegan, vice president of Generation and Environment at EPRI. “These ‘hybrid power plants’ will combine the low-cost reliability of existing fossil power plants with the environmental benefit of renewables, and help companies meet federal and state mandates to reduce their emissions of air pollutants and greenhouse gases with renewable energy.”

The projects will provide a conceptual design study and two detailed case studies. Design options to retrofit existing plants will be analyzed and new plant design options will be identified. EPRI will rely on its expertise in solar technologies, steam cycles and plant operation, as well as past solar and fossil plant studies. EPRI holds two patents in solar steam cycle optimization.

Currently, 27 states in the U.S. have enacted renewable portfolio standard (RPS) policies. Some include specific mandates that a percentage of the requirement be met with solar energy. However, most current solar applications are not cost-competitive with other power-generating options. Using solar to augment coal or natural gas potentially is the lowest-cost option for adding solar power to the generation fleet because it uses existing plant assets. And because the highest-intensity solar energy typically is within a few hours of peak summer loads, it makes solar-augmented steam cycles an attractive renewable energy option.