Natural gas plants with solar boost

A new system under development converts natural gas and sunlight into a fuel called syngas, which power plants can burn to make electricity

04/24/2013


ISS SourceIt might soon be possible for natural gas power plants to use about 20% less fuel when the sun is shining by injecting solar energy into natural gas with a new system under development.

The system converts natural gas and sunlight into a more energy-rich fuel called syngas, which power plants can burn to make electricity.

“Our system will enable power plants to use less natural gas to produce the same amount of electricity they already make,” said the Department of Energy’s (DoE) Pacific Northwest National Laboratory (PNNL) Engineer Bob Wegeng, who is leading the project. “At the same time, the system lowers a power plant’s greenhouse gas emissions at a cost that’s competitive with traditional fossil fuel power.”

PNNL will conduct field tests of the system at its campus in Richland, Wash., this summer.

With the U.S. increasingly relying on inexpensive natural gas for energy, this system can reduce the carbon footprint of power generation. DoE’s Energy Information Administration estimates natural gas will make up 27% of the nation’s electricity by 2020. Wegeng said PNNL’s system works best in 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% less natural gas while producing the same amount of electricity.

This decreased fuel usage is possible with concentrating solar power, which uses a reflecting surface to concentrate the sun’s rays like a magnifying glass. PNNL’s system uses a mirrored parabolic dish to direct sunbeams to a central point, where a PNNL-developed device absorbs the solar heat to make syngas.

About four feet long and two feet wide, the device contains a chemical reactor and several heat exchangers. The reactor has narrow channels as wide as six dimes stacked on top of each other. Concentrated sunlight heats up the natural gas flowing through the reactor’s channels, which hold a catalyst that helps turn natural gas into syngas.

The heat exchanger features narrower channels that are a couple times thicker than a strand of human hair. The exchanger’s channels help recycle heat left over from the chemical reaction gas. By reusing the heat, solar energy is more efficient in its ability to convert natural gas into syngas. Tests on an earlier prototype of the device showed more than 60% of the solar energy that hit the system’s mirrored dish converted into chemical energy contained in the syngas.

PNNL is refining the earlier prototype to increase its efficiency while creating a more cost sensitive design. The project includes developing cost-effective manufacturing techniques that could work in mass production. The manufacturing methods will end up developed by PNNL staff at the Microproducts Breakthrough Institute, a research and development facility in Corvallis, OR, jointly managed by PNNL and Oregon State University.

Wegeng’s team aims to keep the system’s overall cost low enough so 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.

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.

Wegeng also envisions a day when PNNL’s solar-driven system could create transportation fuels. Syngas can also make synthetic crude oil, which can then refine into diesel and gasoline.



No comments
Consulting-Specifying Engineer's Product of the Year (POY) contest is the premier award for new products in the HVAC, fire, electrical, and...
Consulting-Specifying Engineer magazine is dedicated to encouraging and recognizing the most talented young individuals...
The MEP Giants program lists the top mechanical, electrical, plumbing, and fire protection engineering firms in the United States.
Water use efficiency: Diminishing water quality, escalating costs; Lowering building energy use; Power for fire pumps
Building envelope and integration; Manufacturing industrial Q&A; NFPA 99; Testing fire systems
Labs and research facilities: Q&A with the experts; Water heating systems; Smart building integration; 40 Under 40 winners
Maintaining low data center PUE; Using eco mode in UPS systems; Commissioning electrical and power systems; Exploring dc power distribution alternatives
Protecting standby generators for mission critical facilities; Selecting energy-efficient transformers; Integrating power monitoring systems; Mitigating harmonics in electrical systems
Commissioning electrical systems in mission critical facilities; Anticipating the Smart Grid; Mitigating arc flash hazards in medium-voltage switchgear; Comparing generator sizing software
As brand protection manager for Eaton’s Electrical Sector, Tom Grace oversees counterfeit awareness...
Amara Rozgus is chief editor and content manager of Consulting-Specifier Engineer magazine.
IEEE power industry experts bring their combined experience in the electrical power industry...
Michael Heinsdorf, P.E., LEED AP, CDT is an Engineering Specification Writer at ARCOM MasterSpec.