'We have to do everything': Why capturing carbon shows real promise

A range of carbon capture technologies could create valuable products while helping to remove the greenhouse gas from the atmosphere, scientists say.

Carbon capture techniques include a range of ideas, from planting more trees to absorb carbon dioxide from the atmosphere as they grow, to using scrubbers to suck up the gas from the smokestack of a coal-fired power plant.

This week an international team of researchers published new work in the journal Nature surveying the technical and economic potential of carbon capture systems to evaluate their strengths and weaknesses, including their potential to make a meaningful dent in the world's carbon problem. 

It was a timely piece of work, as it coincided with the release of a letter signed by 11,000 scientists declaring a "climate emergency," and advising on steps that governments and policy-makers should take to reduce the impacts of climate change.

"Carbon utilization and removal" — using carbon dioxide once it's captured to store it in the long term or to create economically valuable products or services — was among their proposed solutions. 

"These pathways together are important," Ella Adlen, a researcher at the Oxford Martin School in Oxford, U.K., said in an interview with CBC Radio's Quirks & Quarks. 

"However, they are by no means the only thing that is going to move the dial on net emission growth. We have to do everything. We have to reduce our emissions and we have to look at the technologies to pull CO2 back into the atmosphere and into the ground because we didn't reduce our emissions in the past."

Carbon utilization and removal could act as an incentive for CO2 removal and could reduce emissions by displacing fossil fuels.

Adlen was a lead author of the new study. She and her team evaluated 10 technologies or pathways that could be scaled up to use and remove carbon dioxide. They included:

• Carbon sequestration in soil, such as reducing tillage of crops.
• Technologies for incorporating carbon dioxide in construction materials like concrete.
• Durable, lightweight plastics that use carbon dioxide as a stable backbone for certain polymers instead of fossil fuels.
• Sustainably harvested lumber that is specially treated to be longer lasting and more fire resistant.
• Growing micro-algae in "bioreactors" to fix carbon dioxide from the air that can be used as a feedstock for biofuels.

Sustainable plastic?

Adlen said the current wave of global urbanization represents a chance to lock up CO2 for the long-term through building materials that could sequester carbon, including concrete and wood.

Unfortunately she pointed out that many of the concrete technologies, specifically, are at an early stage of development and complex regulation of the construction industry could be a barrier.

Plastics are another possibility. While there are global efforts to reduce single use plastics, Adlen said about 60 per cent of the plastics market is devoted to long-term, durable, lightweight plastic, which is enormously useful, and could store carbon for some time.

"The challenge for the plastics industry is to design new, sustainable materials to move away from fossil fuel feedstocks," Adlen said. "One way in which we can do that is actually to use CO2. CO2 can be a wonderful, stable backbone for certain types of polymers."

Overall, the researchers estimated each pathway they looked at could take up about 0.5 gigatonnes of CO2 per year.

To put that into perspective, according to the Intergovernmental Panel on Climate Change, keeping global warming to 1.5 degrees will require the removal of CO2 from the atmosphere on the order of 100 to 1,000 gigatonnes of CO2 over the 21st century. 

Adlen is cautiously optimistic, calling CO2 utilization "one weapon in the arsenal" that needs to grow larger with investment to scale in time that IPCC scientists believe humans have left to fix the climate.

"Governments and corporations are moving on this, but not quickly enough," Professor Cameron Hepburn, director of the Oxford Smith School of Enterprise and Environment, said in a release.