Natural gas power plants can use about 20 percent less fuel when the sun is shining by injecting solar energy into natural gas with a new system being developed by the Department of Energy’s Pacific Northwest National Laboratory. The system converts natural gas and sunlight into a more energy-rich fuel called syngas, which power plants can burn to make electricity.
PNNL’s system is best suited for power plants located in sunshine-drenched areas such as the American Southwest.
Installing PNNL’s system in front of natural gas power plants turns them into hybrid solar-gas power plants. The system uses solar heat to convert natural gas into syngas, a fuel containing hydrogen and carbon monoxide. Because syngas has a higher energy content, a power plant equipped with the system can consume about 20 percent less natural gas while producing the same amount of electricity.
Natural gas is about 27% of US energy production. Wide adoption of this concentrated solar would add a 1.3% solar energy component (25% of 20%). It would still only work in daylight hours. In theory, this solar would need minimal energy subsidies.
The system is adaptable to a large range of natural gas power plant sizes. The number of PNNL devices needed depends on a particular power plant’s size. For example, a 500 MW plant would need roughly 3,000 dishes equipped with PNNL’s device.
Unlike many other solar technologies, PNNL’s system doesn’t require power plants to cease operations when the sun sets or clouds cover the sky. Power plants can bypass the system and burn natural gas directly.
Though outside the scope of the current project, Wegeng also envisions a day when PNNL’s solar-driven system could be used to create transportation fuels. Syngas can also be used to make synthetic crude oil, which can be refined into diesel and gasoline than runs our cars.
Wegeng’s team aims to keep the system’s overall cost low enough so that the electricity produced by a natural gas power plant equipped with the system would cost no more than 6 cents per kilowatt-hour by 2020. Such a price tag would make hybrid solar-gas power plants competitive with conventional, fossil fuel-burning power plants while also reducing greenhouse gas emissions.
PNNL’s concentrating solar power system for natural gas power plants, installed on a mirrored parabolic dish.