The U.S. possesses large reserves of natural gas, but the fuel powers few of the country’s vehicles due partly to storage limitations. Penn State researchers are seeking to overcome this challange by creating a less expensive and more efficient natural gas storage system with funding from the U.S. Department of Energy (DOE).
Mike Chung, professor of materials science and engineering in the College of Earth and Mineral Sciences, received a three-year, $1.12 million grant to develop super-absorbent materials designed to store natural gas under less extreme pressures and temperatures than those required today. The technology could lead to smaller and less-expensive onboard tanks for natural gas vehicles and may make the fuel more economical for tractor-trailers.
Chung’s group previously created a polyolefin polymer product called i-Petrogel that can absorb 40 times its weight in oil while not absorbing water, showing great promise for cleaning up or remediating crude oil spills. With the funding, the researchers will create a new Petrogel polymer tailored to absorb methane, the main component of natural gas used to heat homes and power vehicles.
“We are certainly very excited for the opportunity to do this research that could expand Petrogel for use in natural gas storage,” says Chung. “We can see several advantages in using natural gas for transportation: it’s abundant, less expensive and a cleaner energy source than other fossil fuels. Natural gas is also produced by renewable natural resources like biomass and agriculture byproducts.”
Despite the advantages, compressed natural gas (CNG) requires high-pressure storage tanks made from expensive materials like carbon fiber. Liquefied natural gas (LNG), another storage option, offers better energy density but requires extremely low temperatures, making it an expensive option typically reserved for shipping fuel over long distances. Chung said converting LNG to CNG for commercial use also costs up to a third of what the fuel is worth.
The researchers are seeking to develop a Petrogel product that doubles the energy density of CNG and that is effective at room temperatures and under low pressures. This would allow for storage in inexpensive steel tanks. The material, which looks like a sponge, has networks of small holes that allow hydrocarbons to diffuse inside. As it absorbs oil or gas, its outside volume doesn’t change.
Methane molecules are the most difficult hydrocarbon to capture and condense. The researchers will spend the first phase of the project identifying the right polymer blend to address that challenge.
“If we can help the farmer to store methane, I think it’s going to be a very important technology,” adds Chung. “Their agricultural byproduct could have an economic value that’s also good for the environment.”