What are the most effective greenhouse gas capture and storage methods?

1 Pre-combustion capture

Pre-combustion capture is a method that removes CO2 from the fuel before it is burned in a power plant or a gas processing plant. The fuel, usually coal or natural gas, is converted into a mixture of hydrogen and CO2, called syngas, through a chemical reaction. The CO2 is then separated from the syngas and compressed for transport and storage. The hydrogen is used as a clean fuel for power generation or other purposes. Pre-combustion capture can achieve high capture rates of up to 90%, but it requires complex and costly equipment and processes.

2 Post-combustion capture

Post-combustion capture is a method that removes CO2 from the flue gas after it is burned in a power plant or an industrial plant. The flue gas, which contains CO2 and other pollutants, is passed through a solvent or a membrane that selectively absorbs or filters out the CO2. The CO2 is then released from the solvent or the membrane and compressed for transport and storage. The solvent or the membrane is regenerated for reuse. Post-combustion capture can be retrofitted to existing plants, but it has lower capture rates of around 60-80% and consumes a lot of energy.

3 Oxy-fuel combustion

Oxy-fuel combustion is a method that burns the fuel in a pure oxygen environment instead of air, which contains nitrogen and other gases. The result is a flue gas that consists mainly of CO2 and water vapor, which can be easily separated by condensing the water. The CO2 is then compressed for transport and storage. The oxygen is produced by an air separation unit, which also consumes a lot of energy. Oxy-fuel combustion can achieve high capture rates of up to 95%, but it requires modifying the combustion system and handling high-purity oxygen.

4 Carbon mineralization

Carbon mineralization is a method that converts CO2 into stable minerals, such as carbonates and bicarbonates, through natural or artificial processes. The CO2 can be injected into underground formations, such as basalt or peridotite, that react with the CO2 and form minerals over time. Alternatively, the CO2 can be mixed with alkaline materials, such as cement or steel slag, that also react with the CO2 and form minerals. Carbon mineralization can permanently store CO2 and prevent leakage, but it is slow and requires large amounts of land and materials.

5 Bioenergy with CCS

Bioenergy with CCS (BECCS) is a method that combines the use of biomass, such as wood, crops, or waste, as a renewable energy source with CCS. The biomass is burned or gasified to produce electricity, heat, or biofuels, and the CO2 is captured and stored. The biomass is assumed to absorb CO2 from the atmosphere during its growth, creating a net negative emission. BECCS can help reduce the overall GHG concentration in the atmosphere, but it faces challenges such as land use, water use, biodiversity, and social impacts.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?