Pacific Northwest National Laboratory

PNNL to use solar to supercharge natural gas

PNNL's Solar Hybrid natural gas dishThe Pacific Northwest National Laboratory (PNNL) will soon test a new technology that will use the sun’s power to supercharge methane or natural gas into a syngas that could reduce fuel consumption at natural gas power plants by about 20 percent while still producing as much energy while the sun shines. The device uses a dish to concentrate the sun on a unit where the sun, water and natural gas come together to produce a gas with much more energy capacity than natural gas alone.

“The system makes syngas by concentrating solar energy onto a chemical reactor,” said PNNL spokesperson Frances White. “Two main things enable the methane-water mix to be converted into syngas: high temperatures provided by the solar energy and catalysts placed inside the chemical reactor. Combined, the catalysts and the high heat enable the atoms in water (two hydrogens, one oxygen) and methane (one carbon, four hydrogens) to be reshuffled into syngas. The primary energy content in syngas is in carbon monoxide (one carbon, one oxygen) and hydrogen,” she said.

The result is more bang for the buck. “Syngas has about 20 percent more chemical energy than methane.….when syngas is burned inside the power plant, it releases more heat than the same amount of natural gas would release. This is why hybrid solar-gas power plants that use PNNL's system could use 20 percent less natural gas (and release 20 percent less carbon dioxide emissions) to produce the same amount of electricity,” White said.

Though still in test phases, the device has already proven efficient at converting methane into syngas. “Tests on an earlier prototype of PNNL's system showed more than 60 percent of the solar energy was converted into a chemical energy in the syngas. PNNL project leader Bob Wegeng and his team expect the revised system they're working on how will be able to convert up to 75 percent of the solar energy into chemical energy,” White said.

The lab will field test the system this summer at its Richland, Wash., campus. The mechanism is about four feet long and two feet wide, with a catalyst in the receiver unit. That chemical reactor is coupled with several heat exchangers. As the concentrated thermal energy from the sun hits the reactor it heats up the natural gas and water turning it into syngas.

The lab is now working to refine the system, to keep its costs low, allowing the syngas technology to produce electricity at no more than 6 cents per kilowatt hour. To bring it to the next level, the lab is already working with the Microproducts Breakthrough Institute, a research and development facility in Corvallis, Ore., jointly managed by PNNL and Oregon State University.