Researchers at MIT have developed a new approach to electrochemical carbon dioxide capture and release, enhancing efficiency by six times and cutting costs by at least 20 percent.
The quest for efficient carbon capture and conversion is crucial in combating climate change. However, existing systems often face a tradeoff between efficient capture and release. Researchers at MIT have developed a new approach that enhances the efficiency of electrochemical carbon dioxide capture and release by six times and cuts costs by at least 20 percent.
Carbon capture is a technology that captures carbon dioxide (CO2) emissions from sources like power plants and industrial processes, reducing their contribution to climate change.
According to the International Energy Agency (IEA), by 2050, around 3.5 gigatons of CO2 could be captured annually.
This technology can be applied to various sectors, including energy production, industry, and even direct air capture.
While still in development, carbon capture has shown promising results, with several large-scale projects already operational worldwide.
Current carbon-capture systems rely on chemicals called ‘hydroxides’ to remove CO2 from the air. However, these compounds are not efficient at releasing captured CO2 once it’s been removed. On the other hand, compounds that efficiently release CO2 are not very effective at capturing it. This tradeoff makes optimizing one part of the cycle difficult, leading to a bottleneck in the overall process.
MIT researchers have added nanoscale filtering membranes to a carbon-capture system, separating the ions that carry out the capture and release steps. This simple intermediate step enables both parts of the cycle to proceed more efficiently. The new approach uses ‘hydroxide ions’ and ‘carbonate ions,’ which are separated based on their charge using nanofiltration.
Nanofiltration is a water purification process that uses semi-permeable membranes with tiny pores to remove impurities from water.
These membranes have pore sizes between 0.001 and 0.01 micrometers, allowing them to filter out dissolved solids, bacteria, viruses, and other contaminants.
Nanofiltration is commonly used in drinking water treatment plants, industrial processes, and wastewater recycling.
It can also be used for desalination of seawater and brackish water.
According to the International Desalination Association, nanofiltration accounts for over 10% of global desalination capacity.
The process begins with a solution containing hydroxide ions, which combine with CO2 to form carbonate. The nanofiltration membranes then separate the carbonate from the hydroxide solution, allowing both parts of the system to operate at their most efficient ranges. Once separated, the hydroxide ions are fed back to the absorption side of the system, while the carbonates are sent ahead to the electrochemical release stage.
Testing showed that the nanofiltration could separate the carbonate from the hydroxide solution with about 95 percent efficiency, validating the concept under realistic conditions. The analysis also revealed that present systems cost at least $600 per ton of carbon dioxide captured, while the new system drops to about $450 a ton. Furthermore, the new system is much more stable, continuing to operate at high efficiency even under variations in the ion concentrations in the solution.
Carbon capture technology is a crucial component in reducing greenhouse gas emissions.
However, the high upfront costs and operational expenses have hindered its widespread adoption.
According to a study by the National Renewable Energy Laboratory (NREL), the cost of carbon capture can range from $60 to $120 per ton of CO2 captured.
This expense is typically passed on to consumers through higher electricity rates or fuel prices.
Despite these challenges, researchers are working to improve efficiency and reduce costs, with some estimates suggesting a potential decrease in costs by 50% within the next decade.
The researchers believe that this approach could apply not only to direct air capture systems but also to point-source systems and conversion processes. They also hope to develop safer alternative chemistries for carbon capture, as many current absorbents can be toxic or damaging to the environment. With ongoing work, they aim to bring down costs further and make it economically viable for widespread adoption.
The development of this new approach marks an important step towards a decarbonized future. By improving the efficiency and economics of carbon capture and conversion, we can make a significant impact on reducing greenhouse gas emissions and mitigating climate change. The researchers’ innovative solution demonstrates the potential for cutting-edge technology to drive positive change in our world.
