Solar energy offers the promise of unlimited clean energy, but currently suffers from high costs and an inherent disadvantage of not working when the sun is not shining. National Laboratory Pacific Northwest Energy is taking a best-of-two-worlds by developing a solar / gas hybrid that increases efficiency and reduces the carbon footprint of natural gas power plants.
PNNL system uses a parabolic mirror to focus sunlight on a four by two meters (1.2 x 0.6 m) chemical reactor narrow channels filled with 8.1 mm (0.318 in) wide. Sunlight heats the natural gas in the adjacent channels to a catalyst which decomposes the gas molecules in a mixture of carbon dioxide and hydrogen called synthesis gas or syngas. Reactor is connected to a heat exchanger that collects the waste heat of reaction and recycled back to the reactor to promote the process of up to 60 percent of the sunlight is converted into chemical energy. The evidence indicates that the system enables a natural gas plant to operate at about 20 percent efficiency.
“Our system will allow power plants to use less natural gas to produce the same amount of electricity that you do,” says Bob Wegeng PNNL engineer, who heads the project. “At the same time, the system reduces emissions of greenhouse gases from a power plant at a cost that is competitive with traditional power from fossil fuels.”
It’s no surprise that the system works best in areas with lots of sun and as PNNL, is adaptable to different sizes of power plant sizes of natural gas with a 500 MW plant requires about 3,000 solar dishes. Furthermore, synthesis gas can also be used to produce synthetic fuels for vehicles.
PNNL plans to test the system on its campus in Richland, Washington, as part of a program to increase system efficiency and reduce the cost for a screening of six cents per kilowatt hour in 2020 to make it competitive with thermal power conventional. In addition, methods aimed at mass production of the system is developed in the Microproducts Breakthrough Institute, a research and development center in Corvallis, Oregon, while partner SolarThermoChemical Industrial LLC to manufacture and sell the system after development.