Research
Our team develops a range of electrochemical processes to assist in mitigating climate change. In the following, you will find the importance and scope of our research activities.
Earth’s climate is now changing faster than at any point in the history of modern civilization, mainly as a result of human activities. This change in our climate resulted in several serious issues including social and economical. Designing any action plan to mitigate climate change must include a detailed strategy to lower greenhouse gas emissions, especially carbon dioxide (CO2). In this context, detailed action plans were designed to limit the global temperature rise. The designed plans suggest that the annual CO2 emissions need to be reduced by ~75% by 2060.
Currently, the global CO2 emission is ~37 gigatons (billion metric tons). Over the past few decades, atmospheric CO2 concentrations have risen steeply; in March 2021, atmospheric CO2 reached 417 ppm, a level higher than any reached in >800,000 years
Electrochemical processes have an important role to reduce global CO2 emissions. By crucially bridging electricity and thermochemistry, electrochemistry is a powerful tool that has multiple intersection points in current energy systems and with the roadmap scenarios. These include more conventional roles, such as electrification of transportation and the use of grid-scale storage to balance renewables supply and demand. An additional role that has been researched extensively for decades, namely electrosynthesis of chemicals and fuels, represents an option to not only utilize excess electricity but also to couple in CO2 as a feedstock, providing a utilization strategy if CO2 can be effectively captured and re-directed through synthetic processes.
In addition to the conventional processes, there are emerging roles for electrochemistry to assist in mitigating climate change. In recent years, various electrochemical processes have been developed to help industries become more energy-efficient and to capture CO2 from either point sources (e.g., power plant flue gas) or air – these tasks can be considered as the new frontiers within the electrochemistry and climate change framework. In our lab, we implement electrochemical approaches to harvest low-grade waste heat as electricity, which results in improving energy efficiency. We also develop various electrochemical systems to selectively remove CO2 from a gas mixture of different sources, aiming to reduce their carbon footprint. We are also interested in implementing machine learning (ML) as a powerful emerging tool for carbon capture processes. Below, please find details for each project we are investigating.
1- Electrochemical processes for low-grade waste heat
Low-grade heat is a large untapped energy resource generated at various industrial plants and available from geothermal sources. Due to the lack of efficient and cost-effective recovery methods, low-grade heat has generally been discarded by industry and has become an environmental concern because of thermal pollution. The critical needs for technologies that convert low-grade waste heat into electricity are high power output, efficiency, scalability, and cost-effectiveness. In our lab, we developed a range of liquid-based electrochemical processes that can effectively convert low-grade waste heat into electricity. For more information, please read the following related articles:
- M. Rahimi, A. P. Straub, F. Zhang, X. Zhu, M. Elimelech, C. A. Gorski, B. E. Logan, Emerging electrochemical and membrane-based systems to convert low-grade heat to electricity, Energy & Environmental Science 11, 276–285, 2018.
- M. Rahimi, T. Kim, C. A. Gorski, B. E. Logan, A thermally regenerative ammonia battery with carbon-silver electrodes for converting low-grade waste heat to electricity, Journal of Power Sources 373, 95–102, 2018.
- M. Rahimi, A. D’Angelo, C. A. Gorski, O. Scialdone, B. E. Logan, Electrical power production from low-grade waste heat using a thermally regenerative ethylenediamine battery, Journal of Power Sources 351, 45–50, 2017.
- M. Rahimi, L. Zhu, K. L. Kowalski, X. Zhu, C. A. Gorski, M. A. Hickner, B. E. Logan, Improved electrical power production of thermally regenerative batteries using a poly(phenylene oxide) based anion exchange membrane, Journal of Power Sources 342, 956–963, 2017.
- M. Rahimi, Z. Schoener, X. Zhu, F. Zhang, C. A. Gorski, B. E. Logan, Removal of copper from water using a thermally regenerative electrodeposition battery, Journal of Hazardous Materials 322, 551–556, 2017.
- X. Zhu, M. Rahimi, C. Gorski, B. Logan, A thermally-regenerative ammonia-based flow battery for electrical energy recovery from waste heat, ChemSusChem 9, 873–879, 2016.
2- Electrochemical carbon capture
Carbon capture plays a key role in achieving the goals of the designated emission mitigation plan, with a reduction share of up to 5 Gt of CO2 per year by 2060. CO2 separation from a mixed gas matrix is the most energy-intensive step of carbon capture, and much effort has gone into developing separation technologies with minimum energy penalty per unit of CO2 captured. State-of-the-art technologies for CO2 capture involve thermal cycles in which a nucleophilic agent captures CO2 from mixed gas streams (e.g., CO2 and N2 in flue gas) followed by a thermal stripping process in which pure CO2 is released and the nucleophilic agent is regenerated. These processes are energy-intensive and face challenges such as capture agent degradation. Electrochemical processes, on the other hand, offer an attractive alternative route with minimized energy requirements. Electrochemical-based CO2 separations have the advantage of being readily integrated as plug-and-play processes that do not require external sources of steam, high pressures, or vacuum to operate. In our lab, we implement a variety of electrochemical reactions to design efficient and scalable carbon capture processes. To develop these capture systems, we perform both fundamental and practical investigations.
For more information, please read the following related articles:
- M. Rahimi, K. M. Diederichsen, N. Ozbek, M. Wang, W. Choi, T. A. Hatton, An electrochemically mediated amine regeneration process with a mixed absorbent for post-combustion CO2 capture, Environmental Science & Technology 54, 8999–9007, 2020.
- M. Rahimi, G. Catalini, S. Hariharan, M. Wang, M. Puccini, T. A. Hatton, Carbon dioxide capture using an electrochemically driven proton concentration process, Cell Reports Physical Science 1, 100033, 2020.
- M. Rahimi, F. Zucchelli, M. Puccini, T. A. Hatton, Improved CO2 capture performance of electrochemically mediated amine regeneration processes with ionic surfactant additives, ACS Applied Energy Materials 3, 10823–10830, 2020.
- M. Rahimi, G. Catalini, M. Puccini, T. A. Hatton, Bench-scale demonstration of CO2 capture with an electrochemically driven proton concentration process, RSC Advances 10, 16832–16843, 2020.
- M. Wang, M. Rahimi, A. Kumar, S. Hariharan, W. Choi, T. A. Hatton, Flue Gas CO2 Capture via Electrochemically Mediated Amine Regeneration: System Design and Performance, Applied Energy 255, 113879, 2019.
3- Smart carbon capture
Machine learning (ML), which is rapidly emerging in many fields, is also having an impact on carbon capture processes, with applications ranging from predictions of thermodynamic properties to an accelerated discovery of materials. These applications of ML have grown over the last few years, fueled by success in the development of advanced and efficient algorithms, enhanced computational power, and the generation of large databases. For cases in which experimental measurements or traditional theoretical calculations are difficult, costly, or even infeasible, ML methods can offer a fast and cost-effective alternative route to advance many aspects of the carbon capture process. As such, ML will certainly impact the future development of carbon capture operations; surely, exciting years lie ahead for this technology, the development of which has only recently begun. In our lab, we use this powerful tool to advance carbon capture processes on many fronts. To know more about the scope of this implementation, please read our recent perspective paper:
- M. Rahimi, S. M. Moosavi, B. Smit, T. A. Hatton, Toward Smart Carbon Capture with Machine Learning, Cell Reports Physical Science 2, 100396, 2021.
If you are interested to know more about the different electrochemical processes we develop for carbon capture, please watch the following video:
The following podcast also describes the general scope of carbon capture, and what we do in our lab to further advance these processes: