Carbon dioxide (CO2) is the main greenhouse gas that causes global warming and climate change. It is emitted by burning fossil fuels, such as coal, oil, and gas, as well as by deforestation, agriculture, and other human activities. According to the Intergovernmental Panel on Climate Change (IPCC), to limit global warming to 1.5°C above pre-industrial levels, we need to reduce CO2 emissions by 45% by 2030 and reach net-zero emissions by 20501
But how can we achieve this ambitious goal? One possible solution is carbon capture, which refers to a collection of technologies that can reduce CO2 emissions by capturing it from the source or from the air, and then storing it or reusing it. In this blog post, I will explain what carbon capture is, how it works, what are its benefits and challenges, and what are some examples of carbon capture projects around the world. As a student of environmental science and a pro in sustainability, I am passionate about exploring and promoting solutions for the climate crisis.
What is Carbon Capture?
Carbon capture and storage (CCS) is a process in which CO2 is separated from the flue gas of industrial sources, such as power plants or factories, before it is released to the atmosphere. The captured CO2 is then compressed and transported to a storage site, usually deep underground in geological formations, such as depleted oil and gas reservoirs or saline aquifers. The aim is to prevent CO2 from entering the atmosphere and contributing to global warming.
Carbon capture and utilization (CCU) is a process in which CO2 is converted into useful products or services, such as fuels, chemicals, plastics, building materials, or enhanced oil recovery. The aim is to create value from CO2 and reduce the dependence on fossil fuels.
Absorption. This is the most widely used technology for CCS. It involves passing the flue gas through a liquid solvent that chemically binds with CO2. The solvent is then heated to release the pure CO2 for compression and storage or utilization. The solvent can be reused for multiple cycles of absorption and regeneration.
Adsorption. This involves passing the flue gas through a solid material that physically attracts CO2 molecules on its surface. The material is then heated or depressurized to release the CO2 for compression and storage or utilization. The material can be reused for multiple cycles of adsorption and desorption.
Membrane separation. This involves passing the flue gas through a thin film that selectively allows CO2 molecules to pass through while blocking other gases. The permeated CO2 stream is then compressed and stored or utilized. The membrane can be made of various materials, such as polymers, ceramics, or metals.
Oxy-fuel combustion. This involves burning fossil fuels with pure oxygen instead of air, which produces a flue gas that consists mainly of CO2 and water vapor. The water vapor is then condensed and separated from the CO2 stream, which is ready for compression and storage or utilization.
Direct air capture (DAC). This involves capturing CO2 directly from the ambient air using chemical or physical processes, such as absorption, adsorption, or electrochemical reactions. The captured CO2 can then be stored or utilized for various purposes.
What are the Benefits and Challenges of Carbon Capture?
Reducing emissions. Carbon capture can prevent large amounts of CO2 from entering the atmosphere and contributing to global warming. According to the IPCC, CCS could contribute up to 13% of the cumulative mitigation effort by 20505 CCU could also reduce emissions by displacing fossil fuels with low-carbon alternatives.
Extending fossil fuel use. Carbon capture can enable the continued use of fossil fuels for electricity generation and industrial processes without compromising climate goals. This could provide a transition pathway for countries that rely heavily on fossil fuels for their energy needs.
Enhancing negative emissions. Carbon capture can create negative emissions when combined with bioenergy sources (such as biomass or biogas) or DAC technologies that remove more CO2 from the atmosphere than they emit. This could help compensate for residual emissions from hard-to-decarbonize sectors or overshoot scenarios.