Scientists Turn Atmospheric Carbon Dioxide into Nanofibers
A group of researchers led by Dr Stuart Licht of George Washington University has developed a novel method to economically convert atmospheric carbon dioxide directly into highly valued carbon nanofibers.
This false-color image shows carbon nanofibers. Image credit: Stuart Licht.
“We have found a way to use atmospheric carbon dioxide to produce high-yield carbon nanofibers. Such nanofibers are used to make strong carbon composites, such as those used in the Boeing 787 Dreamliner, as well as in high-end sports equipment, wind turbine blades and a host of other products,” Dr Licht explained.
Because of its efficiency, the new process can be run using only a few volts of electricity, sunlight and a whole lot of carbon dioxide.
At its root, the system uses electrolytic syntheses to make the nanofibers.
Carbon dioxide is broken down in a high-temperature electrolytic bath of molten carbonates at 1,380 degrees Fahrenheit (750 degrees Celsius). Atmospheric air is added to an electrolytic cell.
“Once there, carbon dioxide dissolves when subjected to the heat and direct current through electrodes of nickel and steel. The carbon nanofibers build up on the steel electrode, where they can be removed,” Dr Licht said.
To power the syntheses, heat and electricity are produced through a hybrid and extremely efficient concentrating solar-energy system.
The system focuses the Sun’s rays on a photovoltaic solar cell to generate electricity and on a second system to generate heat and thermal energy, which raises the temperature of the electrolytic cell.
The scientists estimate electrical energy costs of this ‘solar, thermal, electrochemical process’ to be around $1,000 per ton of carbon nanofiber product, which means the cost of running the system is hundreds of times less than the value of product output.
“We calculate that with a physical area less than 10% the size of the Sahara Desert, our process could remove enough carbon dioxide to decrease atmospheric levels to those of the pre-industrial revolution within ten years,” Dr Licht said.
At this time, the system is experimental. “We are scaling up quickly and soon should be in range of making tens of grams of nanofibers an hour,” Dr Licht said.
One advance the researchers have recently achieved is the ability to synthesize carbon fibers using even less energy than when the process was initially developed.
“Carbon nanofiber growth can occur at less than 1 volt at 1,380 degrees Fahrenheit (750 degrees Celsius), which for example is much less than the 3-5 volts used in the 1,832 degrees Fahrenheit (1,000 degrees Celsius) industrial formation of aluminum.”
Dr Licht and his team reported their results today at the 250th National Meeting & Exposition of the American Chemical Society in Boston, MA.