Capturing carbon
Significant emissions reductions are needed to meet the Paris Agreement goals, but reaching Net Zero will also rely on carbon removal technologies.
Countries and companies will rely on technologies such as Carbon Capture and Storage to remove residual greenhouse gas emissions from the atmosphere.
The role of carbon capture in reaching Net Zero
Science-based Net Zero targets require reducing greenhouse gas emissions from a company’s operations and supply chain by 90% by 2050. Importantly, the remaining 10% of emissions which cannot be reduced should be permanently removed from the atmosphere.
Carbon Capture and Storage (CCS) will be particularly relevant and unavoidable for hard-to-abate sectors such as cement, steel and chemical manufacturing, where decarbonization will be more technologically challenging.
Capturing around 45 million tCO2e per year, implemented CCS projects currently absorb around 0.1% of global greenhouse gas emissions. For both the Intergovernmental Panel on Climate Change and the International Energy Agency, CCS will play a key role on the way to Net Zero.
In the IPCC’s 1.5°C scenarios, CCS projects would mitigate 1 billion tCO2 by 2030 and 3 billion tCO2 by 2050, which is greater than India’s current annual emissions. In such a scenario, 6% of climate change mitigation efforts would come from these technologies.
Reaching this scenario would require scaling the CCS industry by 67 times its current yearly capacity by 2050. A mix of favourable climate policy and economic incentives will be required for this currently expensive industry to flourish.
The process of CCS
CCS technologies rely on a three-step process to reduce emissions and ensure they are permanently stored with no risks of leaking into the atmosphere:
Capture: Technologies installed at high-emission sources such as power generation plants or industrial facilities separate the CO2 from other gases.
Transportation: Once captured, the CO2 is compressed into a liquid state before being transported by pipelines, trucks, rail or ships.
Storage: The CO2 is then injected into deep geological formations or saline aquifers at more than a kilometre of depth to ensure it is permanently stored.
To first capture the CO2, three options are available for emitters of fossil fuels, such as cement manufacturers or gas-fired power plants:
Post-combustion: CO2 is captured from exhaust gases once fossil fuels are burned. This technology can be retrofitted on industrial and power plants.
Pre-combustion: Fossil fuels are first partially burned to generate synthetic gas, trapping the CO2 before the fossil fuels are fully combusted.
Oxyfuel combustion: Fossil fuels are burned in oxygen instead of air, producing gas consisting mainly of CO2 and water vapour. Through condensation, pure CO2 is collected.
Potential in the cement industry
Cement manufacturing is a perfect example of a sector that is hard to abate and will need to leverage CCS technologies on its journey to Net Zero. Accounting for 7% of the world’s greenhouse gas emissions, cement is the second-largest industrial CO2 emitter.
Making cement requires limestone, a raw material for which CO2 makes up 40% of its weight. When the limestone is heated in cement kilns approaching 1,400°C, that CO2 is released. CCS technologies provide the opportunity to absorb these unavoidable emissions.
Heidelberg Materials, one of the largest building materials companies, is building the world’s first industrial-scale CCS project at their cement plant in Brevik, Norway. The project has the potential to achieve yearly reductions of 400,000 tCO2e.
Gases would be captured from the factory’s chimneys, cooled down, and treated before being compressed. This energy-intensive process would be powered by residual heat from the factory. Then, the CO2 would be transported by ship before being injected into reservoirs below the sea bed.
The facility is scheduled to be fully operational this year, and it has the potential to reduce Heidelberg Material’s yearly emissions by 0.3%. If scaled to other facilities and industries, this pilot could create waves of climate action.
Conditions for success
One of the blockers to CCS technologies scaling is their cost. As projects, they are capital-intensive and require high upfront costs. In the power sector, it is estimated that it could cost between 60€ and 90€ per tonne of carbon dioxide captured.
Another potential risk is the fear of leakages from storage sites. However, these geological formations have stored CO2 for millions of years. The IPCC estimates that storage sites would retain over 99% of CO2 injected over 1000 years.
The biggest concern with CCS technologies is that they could be used to prolong the use of fossil fuels. More dangerously, some captured CO2 is used by the fossil fuel industry in enhanced oil recovery to increase oil production in declining fields.
Strong environmental policies are needed to minimize any risks of leakages from storage sites. Economic incentives such as carbon taxes could favour the uptake of CCS technologies by high emitters wishing to avoid paying fines.
More importantly, CCS technologies should be implemented alongside significant emission reduction initiatives. They should not be used to perpetuate our reliance on fossil fuels but rather be a complementary solution for hard-to-abate sectors on their decarbonization journey.
