A recent study in Nature reveals a breakthrough in reducing the energy demands of carbon capture, utilisation and storage (CCUS) through a novel biphasic absorbent technology.
Developed to improve carbon absorption and mineralisation efficiency, the findings could reshape the way industries approach carbon capture by simplifying processes and lowering costs, according to authors of the study.
Researchers explored the potential of a DEEA/AEP biphasic absorbent to capture carbon dioxide (CO2), followed by targeted phase separation and mineralisation.
In this process, only the CO2-enriched phase of the solution undergoes mineralisation – substantially cutting down on the volume of solution needed and thereby optimising energy use. “By focusing on the CO2-rich phase alone, we can minimise mineralisation solution requirements, reducing both equipment scale and energy consumption,” explained the study authors.
At the core of this innovation is the DEEA/AEP absorbent’s ability to achieve high mineralisation levels under low energy conditions.
What is a biphasic absorbent? A biphasic absorbent is a special solution used in carbon capture that separates into two layers, or phases, after absorbing CO2. Only the CO2-rich phase is processed further, which saves energy and resources. This method is more efficient than traditional carbon-capturing solutions that don’t separate into phases. Biphasic absorbents are typically made from combinations of chemical solvents like DEEA (N,N-diethylethanolamine) and AEP (aminoethylpiperazine). These chemicals work together to absorb CO2 and naturally separate into two layers. The CO2 concentrates in one layer, which makes it easier and less energy-intensive to process and store.
Under specific conditions, such as a temperature of 50°C and a calcium-to-carbon (Ca/C) molar ratio of 1, the research team reported a mineralisation rate of 95.73% after just 30 minutes of ultrasonic treatment. According to the team, the absorbent system displayed high recyclability, with minimal decrease in CO2 load over six absorption cycles.
The study was designed to illustrate the energy-saving potential of the biphasic absorbent in contrast to conventional CCUS methods. Traditional approaches often require high-temperature regeneration to release captured CO2 from the absorbent, resulting in considerable energy expenditure.
However, this new biphasic approach maintains regeneration temperatures below 100°C, with the added advantage of stabilising CO2 directly within solid carbonates—a crucial step toward reducing the carbon footprint of CCUS technology. “By avoiding high-temperature desorption and sequestering CO2 in a stable carbonate form, this technology presents a viable alternative to energy-intensive thermal methods,” the authors highlighted.
Laboratory tests, such as thermal gravimetric analysis, X-ray diffraction, and nuclear magnetic resonance, were used to verify the strength and effectiveness of the biphasic system.
According to the study, adjusting the temperature, Ca/C ratio, and dispersion level notably impacted the mineralisation efficacy, with higher temperatures correlating with increased CO2 desorption rates and a richer carbonate content in the final product.
Globally, carbon capture and mineralisation projects are expanding as industries seek sustainable solutions to reduce emissions. Companies like Carbon Clean, Climeworks and Carbfix are pioneering technologies to capture CO2 and store it as stable minerals, primarily in basalt rock formations.
Climeworks, for instance, operates the Orca plant in Iceland, capturing around 4,000 tonnes of CO2 annually, at a cost of approximately $600 per tonne, though costs are expected to decline with scaling. Another major player, Carbfix, focuses on injecting CO2 into rock, turning it into a solid within two years, offering a long-term carbon storage solution.
The full study – ‘Experimental study on the cyclic mineralization of CO2enriched phase after absorption by a novel biphasic absorbent composed of DEEA and AEP’ – can be accessed here.
