May 8, 2013
Energy Production From Natural Gas More Efficient With New Mechanism
April Flowers for redOrbit.com - Your Universe Online
A new mechanism to convert natural gas to energy up to 70 times faster than current methods has been identified by chemical engineering researchers. This new mechanism also effectively captures the greenhouse gas carbon dioxide (CO2).
“This could make power generation from natural gas both cleaner and more efficient,” says Fanxing Li, assistant professor of chemical and biomolecular engineering at North Carolina State University.
The process used to convert natural gas to energy is called chemical looping. A solid, oxygen-laden material, called an “oxygen carrier,” is put into contact with the natural gas where the oxygen atoms in the carrier interact with the natural gas, causing combustion. The combustion reaction is what produces energy.
Previously, state-of-the-art oxygen carriers were made from a composite of metal oxides and inert ceramic material. Li´s team, however, has created a new type of oxygen carrier. The new carrier includes a “mixed ionic-electric conductor” that effectively shuttles oxygen atoms into the natural gas very efficiently. This efficiency makes the chemical looping combustion process as much as 70 percent faster than with traditional oxygen carriers.
The mixed ionic-electric conductor material is held in a nanoscale matrix with an iron oxide — rust, basically — which serves as a source of oxygen for the mixed conductor to shuttle out into the natural gas.
The combustion process produces water vapor and CO2 in addition to energy. The researchers are able to create a stream of concentrated CO2 by condensing out the water vapor. This CO2 is captured for sequestration.
Smaller chemical looping reactors become more economically feasible with the new oxygen carrier´s efficiency. The same amount of energy can be produced with a smaller system.
“Improving this process hopefully moves us closer to commercial applications that use chemical looping, which would help us limit greenhouse gas emissions,” Li says.
Results of this study were published in the journal ACS Sustainable Chemistry & Engineering.