Japan's new carbon capture system aims to overcome these hurdles with "solid-liquid separation" technology that directly removes CO2 from the atmosphere. The new system is claimed to be the fastest in the world, 99% efficient at low CO2 concentrations and twice as fast as existing DACs.
Many scientists believe that the consequences of climate change can be unpleasant. Therefore, technologies are being developed to reduce carbon emissions (one of the main anthropogenic factors of climate change). In addition to reducing atmospheric carbon, scientists see an opportunity to reuse captured CO2. Existing technologies allow capturing, storing and converting CO2 into other chemical compounds suitable for reuse in industry. However, there are still a few hurdles to overcome before current DAC technologies can be applied on a large scale. One issue is efficiency, as the concentration of CO2 in the air only allows for very slow chemical reactions with the trapped substances. In addition, captured CO2 is difficult to recover and reuse, as the chemical reactions for desorption are very energy intensive.
A new study led by Tokyo Metropolitan University concerns DAC in liquid-solid separation systems. Usually this type of separation works according to the basic principle of sedimentation, i.e. in a mixture of liquid and solid, denser bodies accumulate at the bottom of the container under the action of gravity. But in a continuously operating liquid-solid separation system, the solid particles do not have time to completely settle, so the liquid remains loaded with solid particles at the outlet of the system. On the other hand, most DACs pass air through a liquid where a chemical reaction takes place between the liquid and CO2. As the reaction proceeds, the amount of reaction product accumulates in the liquid, making subsequent reactions progressively slower.
A novel solid-liquid separation system, presented in a study published in ACS Publications, removes an insoluble solid reaction product from a solution. Therefore, there is no accumulation of solid particles in the liquid, and the reaction rate does not slow down. They then discovered that one of their aqueous solutions, namely isophorone diamine (IPDA), could capture and convert 99% of the CO2 in the air into a solid carbamic acid precipitate.
In addition, heating the particulate solid in solution to 60°C is sufficient to reverse the reaction, whereby CO2 is released again and the original liquid is reduced. In addition, the CO2 removal rate was at least twice that of conventional laboratory DAC systems, making it the fastest of its kind in the world, and at low CO2 concentrations. The Japanese team also believes that their new process could eventually be applied on a large scale. The use of captured carbon in industry and household products will also be explored, making the new capture system a one-stop solution.