Carbon Dioxide Removal: A Key Strategy for Fighting Climate Change

In the global push to address the negative impacts of climate change, carbon dioxide removal has emerged as a key economic and environmental strategy. Methods such as direct air capture, direct ocean capture, bioenergy and soil carbon sequestration may help reduce emissions, particularly in sectors such as agriculture and air transportation.

Although the economic prospects of CDR are promising, obstacles such as high costs and energy-intensive processes remain. Recent research highlights the need to accelerate carbon removal, as current plans may fall short of meeting Paris Agreement benchmarks.

Two University of Houston experts offer their different perspectives on CDR and its role in the energy transition.

Tracy Hester is an associate instructional professor of law, teaching environmental law at the UH Law Center. He is also co-director of the Environment, Energy and Natural Resources Center and founding co-director of the UH Center for Carbon Management in Energy. His research focuses on the innovative application of environmental laws to emerging technologies, including climate engineering, deep decarbonization, nanoscale materials and microplastics, and climate liability.

Mim Rahimi is an assistant professor of environmental engineering at the UH Cullen College of Engineering and an affiliate faculty with the Materials Science and Engineering program. His research lab is developing a range of electrochemical processes to help industries become more energy efficient and to capture carbon dioxide from ocean and air point sources. His research team’s specific interests include energy and sustainability, electrochemical processes, and using artificial intelligence for climate mitigation.

TRACY HESTER
Instructional Associate Professor of Law

Leveraging the Power of Policy

What role does policy play in the CDR arena impacting decarbonization and clean energy efforts?

TH: Without policy incentives and help with regulatory roadblocks, carbon dioxide removal simply won’t happen as quickly as we need.

Capturing greenhouse gases from ongoing human activities, as well as addressing our historical buildup of past greenhouse gas emissions, requires government policies that provide financial incentives to capture the gases, remove regulatory roadblocks to building these projects, and map out how to protect vulnerable communities and companies working in this area against unexpected disruption and liabilities.

What implications does CDR have for climate justice, and which stakeholders will be affected?

TH: CDR could have deep implications for climate justice, but it all depends on how we approach it. If we place large industrial machinery to capture greenhouse gases in vulnerable communities that already bear an outsized burden, CDR could aggravate concerns about climate justice.

But CDR that targets ambient greenhouse gases that already exist in the atmosphere can go virtually anywhere, depending on the technology and disposal method. Even CDR that goes into environmental justice communities can still transparently and intelligently address concerns of the community and prevent new projects from aggravating existing problems — or even improve them.

Tracy Hester serves on the American Bar Association’s Climate Change Task Force and represented the ABA three times as a delegate to the UN Climate Conferences of Parties (2021-2023). In 2023, he was inducted as a senior fellow of the Global Council on Science and Environment and served as president-elect of the American College of Environmental Lawyers. Hester was elected to the American Law Institute in 2004 and was named the Top Environmental Lawyer in Houston by Best Lawyers of America in 2011.

MIM RAHIMI
Assistant Professor of Environmental Engineering

Researching a Path to Cleaner Energy

How should we support research and development in the CDR arena to more effectively meet goals related to decarbonization and clean energy efforts?

MR: Support should focus on existing technologies, such as direct air capture, as well as emerging technologies.

Although land-based CDRs such as bioenergy with carbon capture and storage and direct air capture have received significant attention, they have drawbacks, such as land requirements and cost. This underscores the need for exploration of promising alternatives such as ocean-based CDRs.

Ocean-based CDRs capitalize on the natural tendency of ocean systems to absorb carbon dioxide from the atmosphere. A number of these technologies, including ocean alkalinization, ocean fertilization and artificial upwelling/downwelling, are under development but have not yet reached commercial viability.

Share how your research is contributing to CDR efforts.

MR: In our lab, we are developing a wide range of electrochemically driven direct ocean capture processes, from fundamental research to practical large-scale implementations. These processes offer several advantages, such as scalability, modularity and cost-effectiveness.

What markets and opportunities exist for CDR?

MR: Several markets exist for the carbon dioxide captured through CDR processes, but the most common application is in enhanced oil recovery. Other emerging applications include precursors for cement production, the food industry and agriculture.

Mim Rahimi, Ph.D., won the prestigious National Science Foundation CAREER Award for his proposal “Leveraging Liquid-Liquid Interfaces for Innovative Electrochemical Carbon Capture” in 2024. Rahimi and his team of doctoral students won the UH-Chevron $25K Energy Transition Challenge in 2023 and the U.S. Department of Energy’s National Energy Tech University Prize of 2024. He earned his doctorate in chemical engineering from Penn State and was a postdoctoral associate in the Department of Chemical Engineering at the Massachusetts Institute of Technology.