ISTC is collaborating with the Illinois State Geological Survey, the Applied Research Institute, and external partner Trimeric Corporation of Buda, Texas, to develop an innovative, low-cost approach for carbon capture from burning coal during electrical generation.
Lab-Scale Project
With funding from the U.S. Department of Energy in October 2015, ISTC assisted ISGS in developing a novel biphasic solvent process at a lab scale (10KWe) for CO2 capture. The objectives of this lab-scale research project were to demonstrate a novel biphasic CO2 absorption process (BiCAP) and generate engineering and scale-up data to leverage the technology to the bench- or small pilot-scale demonstration level.
New Technology vs. Conventional Carbon Capture
The conventional CO2 absorption process (e.g., Monoethanolamine [MEA]) starts with carbon dioxide-rich flue gas entering the absorber, where the CO2 is absorbed and mixed with a solvent (in this case MEA); the clean gas leaves the top of the absorber. The CO2-rich solvent then passes through a heat exchanger and a stripper, where the solvent is stripped of CO2 and returned to the absorber. The concentrated CO2 is then pressurized. While conventional carbon capture methods are effective in removing CO2, they are very energy intensive and nearly double the cost of generating energy.
Introducing a biphasic solvent method after the absorber increases stripping capacity because the CO2 concentration is higher in the second solvent phase. In addition, less energy and compression work are required to compress the CO2. However, the equipment needed is still the same size as the conventional carbon capture technology, making this method only slightly less cost-intensive.
In Period I of this project, ISGS developed an advanced biphasic CO2 absorption process, dubbed BiCAP, which has multi-liquid-liquid phase separation (LLPS) that allows low CO2 loading throughout absorption, resulting in faster kinetics. In addition, BiCAP solvents have larger solvent capacities for both absorption and stripping, which further reduces the heat needed, compression work requirements, and CO2 stripper size. ISTC researchers evaluated the thermal and oxidation stabilities of biphasic solvents to help identify the best option for this study.
In Period II of this project, ISTC and ISGS are studying the corrosive properties of solvents on carbon and stainless steel, which are materials used in power plants. Those results will provide important information for future scale-up of this BiCAP process.
Related Publications
- Modeling, Design, and Testing of a Novel Biphasic Solvent-Enabled Absorption System for Post-Combustion Carbon Capture (15th International Conference on Greenhouse Gas Control Technologies GHGT-15; 5-8 Oct 2020, Abu Dhabi, UAE)
- Phase Change Solvents for Post-combustion CO2 Capture: Principle, Advances, and Challenges (Applied Energy 239(1), 876-897 (2019)).
- Experimental Investigation and Thermodynamic Modeling of Phase Transition and Equilibria in a Biphasic Solvent System for CO2 Capture (Industrial & Engineering Chemistry Research 57(29), 9627-9640 (2018)).
Bench-Scale Project
In spring 2018, ISGS and ISTC received additional U.S. DOE funding for a three-year bench-scale (40kWe) project to further evaluate and test their biphasic CO2 extraction method (BiCAP).
The primary goal of this new project is to leverage the BiCAP process and validate its technical advantages through a fully-integrated bench-scale testing in a relevant flue gas environment. The proposed technology aims to achieve a CO2 capture cost of $30/tonne and >95% CO2 purity to meet DOE’s Transformational CO2 Capture goals.
Results from the 40kWe bench-scale unit fabricated and installed at Abbott Power Plant showed that:
- Monoethanolamine (MEA) or biphasic solvent was stable during bench-scale unit operation.
- MEA had a lower gas treatment capacity than BiCAP solvent for the same unit.
- Amine vapor emissions from BiCAP1 solvent were less than those from MEA, consistent with previous laboratory measurements.
- Initial tests for BiCAP1 revealed a heat duty of ~2,200-2,800 kJ/kg of CO2 captured vs. the optimal 4,000-4,500 kJ/kg for MEA solvent.
- Bench-scale tests are in progress and will verify whether BiCAP2 performs better than BiCAP1 in previous lab-scale tests.
