Climate-warming carbon dioxide could be removed from the air and used directly to make nanofibers for industrial materials, researchers have found.
The new method by researchers from George Washington University, USA, relies on cheap electrolytic synthesis requiring only a few volts of electricity, sunlight and the CO2.
Presenting the technique at a meeting of the American Chemical Society, the researchers said the method could turn the whole greenhouse gas problem upside down, making it a valuable source of high-grade industrial material instead of a painful Earth-threatening issue.
“We have found a way to use atmospheric CO2 to produce high-yield carbon nanofibers,” said Stuart Licht, who led the research team at George Washington University. “Such nanofibers are used to make strong carbon composites, such as those used in the Boeing Dreamliner, as well as in high-end sports equipment, wind turbine blades and a host of other products.”
The researchers are using an extremely efficient hybrid concentrating solar-energy system that combines an electricity generating photovoltaic solar cell and a heat and thermal energy generator.
The heat and thermal energy generator equipped with an electrolytic cell breaks down the CO2 from the air at high temperatures of up to 750 °C in a bath of molten carbonates. Subsequently, carbon nanofibers build on a steel electrode from where they can be removed.
“Carbon nanofiber growth can occur at less than 1 volt at 750 °C, which for example is much less than the 3-5 volts used in the 1,000 °C industrial formation of aluminium,” said Licht.
Licht estimates electrical energy costs of this solar thermal electrochemical process to be around $1,000 per ton of carbon nanofibers, 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 per cent the size of the Sahara Desert, our process could remove enough CO2 to decrease atmospheric levels to those of the pre-industrial revolution within 10 years,” he said.
The major challenge, the researcher said, is to achieve consistency in the size of nanofibers as well scaling up the process to meet industrial needs.
“We are scaling up quickly and soon should be in range of making tens of grams of nanofibers an hour,” he said.