Explainer: What is direct air capture and how can it fight climate change?

Governments and companies are investigating CO2 removal as climate action intensifies.

Direct Air catch (DAC) businesses have been granted $3.5 billion by the U.S. to catch and store the gas.

Here’s how cutting-edge technology works and its promise and limitations.

It works how?
DAC technology chemically removes carbon dioxide from the air and stores it in underground caves or uses it to make concrete or aviation fuel.

Climeworks’ Orca plant in Iceland can store 4,000 tonnes of CO2 underground.

The U.S. program wants to support million-tonne-a-year plants.

Trees, too?
Planting trees and managing forests should help fight climate change. According to the World Resources Institute, doing so costs less than $50 per ton, compared to DAC, which costs in the high triple digits.

Due to the amount of area needed to remove all the trees, many scientists feel technical solutions will be needed.

Other carbon removals?
BECCS is another method. Burning biomass like wood pellets and collecting and storing emissions generates electricity.

When organic matter like leaves, wood, or straw is roasted at high temperatures without oxygen, it produces biochar, a carbon-rich fertilizer that stores carbon in soil.

Seawater CO2 removal methods are being developed.

About CCS?
Industrial smokestacks like fossil fuel power stations use carbon capture and storage (CCS) technology to absorb and store CO2.

CCS is not considered a removal unless it captures more CO2 than the industrial process emits.

Removals can permanently remove previous emissions by storing them in soils, rocks, forests, seas, and products.

Green groups’ opinions?
Most environmental activists acknowledge that certain carbon removals would be needed to meet global climate targets, but they worry that firms may use carbon removal development as an excuse not to reduce their emissions.

DAC and biomass-to-electricity are also questioned by environmentalist groups.

DAC may allow fossil fuel firms to continue production in minority and low-income regions near heavy emission sites, raising environmental justice concerns.