A pilot eSolar plant which uses sun-tracking mirrors to create heat to make steam which makes electricity through a conventional turbine.

When it comes to power plants, General Electric sees natural gas as solar and wind energy's best friend.

GE today said that it has licensed solar thermal technology from California-based eSolar for use in power plants that use both solar and natural gas. As part of the deal, GE has invested an undisclosed amount in eSolar.

Under the agreement, GE will offer a power plant that incorporates eSolar technology with GE's natural-gas turbines designed specifically for operating with large-scale solar and wind installations. The FlexEfficiency combined cycle natural-gas plant is designed to ramp power generation up and down more quickly than conventional plants to work well with variable solar and wind.

eSolar has designed a concentrating solar thermal power plant that uses thousands of computer-controlled, sun-tracking mirrors, or heliostats, that concentrate light onto a tower. The heat creates steam which is fed into a conventional steam turbine to generate electricity.

GE said that a power plant that combines eSolar's solar thermal system with its FlexEfficiency 50 Combined Cycle Power Plant will have an overall efficiency of 70 percent, higher than modern efficient natural-gas turbines. The license also allows GE to build stand-alone solar power plants without natural-gas generation.

GE&39's FlexEfficiency natural-gas power plant is designed with a turbine that fluctuates power generation rapidly to accommodate solar and wind.

"The addition of eSolar's high temperature tower technology to our FlexEfficiency combined cycle power plant is an important step forward for our industry because it allows us to offer an (integrated solar combined cycle) power plant that creates more value for customers at a competitive cost," Paul Browning, president and CEO of thermal products for GE Energy, said in a statement. "As a part of this transaction, GE is becoming an investor in the technology as well as the primary channel to the power industry [through] the license arrangement."

Concentrating solar power systems operate best in desert areas with the right sunlight. GE said it expects to offer the combined solar/natural-gas power plants with investor and developer MetCap Energy in Europe, Africa, the Middle East, and the U.S.

For eSolar, adding GE as a distribution partner gives more marketing muscle in sales to utilities and power plant generators. The company built a small-scale power plant in Southern California and has technology license deals with other energy project developers.