LOS ANGELES (Reuters) - A U.S. utility group announced on Monday a plan to test adding solar thermal energy to natural gas and coal-fired power plants in a move designed to cut fuel costs and greenhouse gas emissions.

The Electric Power Research Institute said Dynegy Inc and NV Energy will host case studies of the technology at natural gas plants in Arizona and Nevada, respectively.

Both projects will add steam generated by a solar thermal field to a conventional natural gas-powered steam cycle, EPRI said. Tests at coal-fired facilities will be announced around the beginning of next year.

Southern Company, Progress Energy Inc and Salt River Project are also providing funding for the projects.