HOUSTON, TX: A new process developed by the Rice University lab of chemist James Tour can turn bulk quantities of just about any carbon source – i.e. a banana peel - into valuable graphene flakes at a fraction of the current price of up to US$200,000 a ton.

Graphene is a one-atom-thick layer of carbon atoms arranged in a hexagonal lattice that is 200 times stronger than steel. It is an excellent conductor of heat and electricity and when combined with other elements, including gases and metals, can produce batteries, transistors, computer chips, energy generation, supercapacitors, DNA sequencing, water filters, antennas, touchscreens and solar cells.

Tour says the “flash graphene” process using a custom-designed reactor can convert a ton of coal, food waste or plastic into graphene for a fraction of the cost used by other bulk methods.

“This is a big deal. The world throws out 30 – 40 percent of all food, because it goes bad, and plastic waste is of worldwide concern. We've already proven that any solid carbon-based matter, including mixed plastic waste and rubber tires, can be turned into graphene.”

Tour hopes to produce a kilo a day of flash graphene within two years in a project to convert American coal funded by the U.S. Department of Energy. “This could provide an outlet for coal in large scale by converting it inexpensively into a much-higher-value building material,” he said.

Flash graphene is made in 10 milliseconds by heating carbon-containing materials to about 5,000 degrees Fahrenheit. Food and plastic waste, petroleum coke, coal, wood clippings and biochar are prime candidates, according to Tour. “With the present commercial price of graphene being US$67,000 - US$200,000 per ton, the prospects for this process look superb.”

As little as 0.1 percent of flash graphene in the cement used to bind concrete could lessen its environmental impact by a third. Cement production emits as much as 8.0 percent of human-made CO2 every year.

“By strengthening concrete with graphene, we could use less concrete for building, and it would cost less to manufacture and less to transport,” he said. “Essentially, we’re trapping greenhouse gases like carbon dioxide and methane that waste food would have emitted in landfills. We are converting those carbons into graphene and adding that graphene to concrete, thereby lowering the amount of carbon dioxide generated in concrete manufacture. It’s a win-win environmental scenario using graphene.”

“With our method, that carbon becomes fixed,” he added. “It will not enter the air again.”

Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of computer science and of materials science and nanoengineering at Rice University.