A new technology being developed at a Department of Energy laboratory could turn natural gas power stations into hybrid solar plants.
The device being developed by Pacific Northwest National Laboratory is about four feet long and two feet wide and contains a chemical reactor and several heat exchangers. Concentrated sunlight heats up the natural gas flowing through the reactor's narrow channels, which hold a catalyst that helps turn natural gas into syngas, a more energy-rich fuel.
The solar concentrators would generate steam at 700C to produce a methane steam reforming reaction to achieve a 20% – 25% increase in efficiency at natural gas power plants.
Engineer Bob Wegeng, who is leading the project at Pacific Northwest National Laboratory, said: “We're augmenting the natural gas fuel content by about 25% so you need that much less natural gas to start with to make the same amount of power. You end up producing about 20% less CO2 and require about 20% less methane.”
Wegeng said applications so far would be in the power sector in the sunny south-western United States, but could also apply to the chemicals industry. Syngas can also be used to make synthetic crude oil, which can be refined into transportation fuels.
His team is aiming for a SunShot Initiative target of 6c/kWh by 2020, which would make hybrid solar-gas power plants competitive with conventional, fossil fuel power plants while also reducing greenhouse gas emissions. A 500 MW plant would need roughly 3,000 dishes equipped with PNNL's device.
But Wegeng said that the technology could be commercial in as little as three years.
“Our challenge is to build a reaction system cheap enough so that when they're mass produced, you would actually find economic advantage to it,” he said. “We're racing at it right now to see how quickly can we get this commercialised. We're pushing hard for efficiency and mass production of components in parallel.”
PNNL will conduct field tests at its campus in Richland, Washington, this summer. Tests on an earlier prototype showed more than 60% of the solar energy that hit the system's mirrored dish was converted into chemical energy in the syngas.
The current project is receiving about $4.3 million combined from DOE's SunShot Initiative and industrial partner SolarThermoChemical LLC of Santa Maria, California. SolarThermoChemcial has a Cooperative Research and Development Agreement for the project and plans to manufacture and sell the system after the project ends.