Using Solar Power to Increase Energy Content of Natural Gas by 25%

The Department of Energy's Pacific Northwest National Laboratory (PNNL) has announced a system that converts natural gas using sunlight into the more energy-rich fuel called syngas.  The new system offers a 25% increase in available energy.

Making the syngas uses concentrated solar power. Solar energy comes to a reflecting surface that concentrates the sun's rays like a magnifying glass. PNNL's system uses a mirrored parabolic dish to direct sun light to a central point, where a PNNL-developed device absorbs the solar heat to make syngas.

Thermochemical Conversion Device Devised by PNNL.

The device is about four feet long and two feet wide, contains a chemical reactor and several heat exchangers. The reactor has narrow channels that are 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 the natural gas into syngas.

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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 of the gas. By reusing the heat, solar energy is used more efficiently to convert the 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 was converted into chemical energy contained in the syngas.  That is very likely the most effective use of solar energy found to date.

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

PNNL engineer Bob Wegeng, who is leading the project said, "Our system will enable power plants to use less natural gas to produce the same amount of electricity they already make. 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 is refining the earlier prototype to increase its efficiency while creating a design that can be made at a reasonable price. The project includes developing cost-effective manufacturing techniques that could be used for the mass production.  The manufacturing methods will be developed by PNNL staff at the Microproducts Breakthrough Institute, a research and development facility in Corvallis, Ore., that is jointly managed by PNNL and Oregon State University.

The lab work suggests a natural gas power plant could use about 20% less fuel when the sun is shining by using solar energy to power a natural gas to syngas conversion.

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.

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 of the proposed dishes equipped with PNNL's device.

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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.

Here's the catch - The current project is receiving about $4.3 million combined from DOE's SunShot Initiative, which aims to advance American-made solar technologies, and industrial partner SolarThermoChemical LLC of Santa Maria, California who has a Cooperative Research and Development Agreement for the project and plans to manufacture and sell the system after the project ends.  In other words, the research was headed for power plant use from the start.

Three thousand dishes is a huge number to purchase, install, manage and maintain.  Another matter is the syngas production could be stored and even transported, with an up rating of energy content by 25% the economics might be quite compelling for other projects.  Perhaps no so much in North America where gas reserves have soared and prices fallen over the past decade, but in much of the world natural gas is much more expensive.  A large solar installation may be much more productive simply converting natural gas to syngas than generating electricity.

These points would also have an effect on the costs of transport compared to liquefied natural gas transport.

PNNL may have hit on a much, much bigger idea with far reaching consequences and benefits than they realize.

You can bet a lot of natural gas producers and consumers are looking at this right now.

Syngas has a higher energy content than natural gas and if a producer could raise the energy value by 25% for no energy or fuel costs - you can bet that someone is going to try to make some market.  If it ships cheaper, can be stored without losing the hydrogen content and transports well someone is going to try to scale up.  Syngas can also be made into the common liquid fuels.

If that happens it would be like a worldwide potential increase of gas reserves by 25%!

By. Brian Westenhaus

Original article: Raising the Energy Value of Natural Gas by 25%