Photo courtesy of Nicolle Rager Fuller, National Science Foundation
Using corncob waste as a starting material, researchers have created carbon briquettes with complex nanopores capable of storing natural gas at an unprecedented density of 180 times their own volume and at one-seventh the pressure of conventional natural gas tanks, according to a report by the National Science Foundation (NSF, www.nsf.gov). The breakthrough is characterized as a significant step forward in the nationwide effort to fit more automobiles to run on methane, an abundant fuel that is domestically produced and cleaner burning than gasoline.
Supported by the National Science Foundation Partnership for Innovation program, researchers at the University of Missouri-Columbia (MU, www.missouri.edu) and Midwest Research Institute (MRI, www.mriresearch.org) in Kansas City developed the technology. The technology has been incorporated into a test bed installed on a pickup truck used regularly by the Kansas City Office of Environmental Quality.
The briquettes are the first technology to meet the 180-to-one storage-to-volume target set by the U.S. Department of Energy (www.doe.gov) in 2000, a long-term goal of principal project leader Peter Pfeifer of MU.
According to Pfeifer, the absence of such a flatbed tank has been the principal reason why natural gas, which costs significantly less than gasoline and diesel and burns more cleanly, is not yet widely used as a fuel for vehicles.
Standard natural gas storage systems use high-pressure natural gas that has been compressed to a pressure of 3600 pounds per square inch and bulky tanks that can take up the space of an entire car trunk. The carbon briquettes contain networks of pores and channels that can hold methane at a high density without the cost of extreme compression, ultimately storing the fuel at a pressure of only 500 pounds per square inch, the pressure found in natural gas pipelines.
The low pressure of 500 pounds per square inch is central for crafting the tank into any desired shape, so ultimately, fuel storage tanks could be thin-walled, slim, rectangular structures affixed to the underside of the car, not taking up room in the vehicle.
Pfeifer and his colleagues at MU and MRI discovered that that fractal pore spaces (spaces created by repetition of similar patterns at different scales) are remarkably efficient at storing natural gas.
The test pickup truck, part of a fleet of more than 200 natural gas vehicles operated by Kansas City, has been in use since mid-October and the researchers are monitoring the technology”s performance, from mileage data to measurements of the stability of the briquettes.
In addition to efforts to commercialize the technology, the researchers are now focusing on the next generation briquette, one that will store more natural gas and cost less to produce. Pfeifer believes this next generation of briquette might even hold promise for storing hydrogen.
