Castles in the air? Carbon dioxide could produce building materials.

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Imagine if all the carbon dioxide emitted by smokestacks and motor vehicles could be used to build skyscrapers instead of polluting the air. It could become a reality, if a new process goes mainstream.

Scientists are converting carbon dioxide (CO2),  a greenhouse gas that contributes to climate change, into carbon threads. The threads are nanofibers, and they may be the building blocks of the future.

Image of magnified carbon nanotube beside an image of threads of carbon nanofibers (Courtesy of Stuart Licht)
A carbon nanotube grown from carbon dioxide is shown, left; nanofiber threads with bright points of carbon nanotube growth, right. (Courtesy photo)

Stuart Licht, lead scientist on a George Washington University team researching this process, thinks making a strong, durable material from thin air can eventually become commercially viable.

His team found that carbon nanofibers are superior to steel in strength, flexibility and conductivity. That makes them useful for many applications — from batteries and electronics to lightweight, high-strength materials used in buildings, aircraft, cars and athletic equipment.

Black roll of industrial fabric unraveling (Shutterstock)
Carbon fiber–reinforced materials, like this roll of Kevlar, are used in many industries. (Shutterstock)

Can greener be cheaper?

Licht presented his team’s findings in 2015. Since then, his team discovered that these nanofibers can grow into an even stronger formation: carbon nanotubes. A recent study showed that CO2 gas from natural gas power plants can be “economically removed and converted to carbon nanotubes,” Licht said.

Two people sitting inside an electric car (© AP Images)
High-performance vehicles such as this electric-powered Tesla benefit from lightweight carbon fiber components. (© AP Images)

Automobile manufacturers already use carbon fiber in place of steel to lighten vehicle weight. But manufacturing carbon fiber is expensive, requiring costly source materials, energy consumption and equipment. Steel and aluminum are cheaper to produce.

Still, if carbon can be efficiently harvested from the abundant amounts of CO2 in the atmosphere, the price tag for carbon fiber–construction could plummet. And Licht says companies have already expressed interest.

A new process uses solar power

It takes a few steps and renewable energy to transform CO2 to carbon nanofibers.

  1. Animated diagram showing how carbon is made from carbon dioxide (State Dept./ D. Thompson)
    (State Dept./ D. Thompson)

    CO2 is captured from the air where emissions are heavy.

  2. Solar energy provides the intense heat and electricity required to break down captured CO2 in a molten carbonate bath.
  3. The CO2 dissolves when it contacts electrified electrodes.
  4. The carbon nanofibers accumulate on the steel electrode.

Licht thinks the process could be done on a scale that would greatly reduce the amount of harmful CO2 emissions caused by human activity.

Environmental scientist Martin Stute, himself involved in breakthrough research to capture CO2 in stone, said that early carbon nanofiber research is encouraging. “There is hope that [carbon nanofibers] can be used in building construction to replace steel and aluminum.”

What’s next? The Licht research group is among teams competing for the Carbon Xprize, which seeks to drive innovative technologies that reduce the impact of climate change by converting CO2 into valuable commercial products.