Weekly CDR Publication Highlights
This week’s selected publications cover issues related to a number CDR methods such as marine CDR, ocean alkalinity enhancement, CO2 capture, conversion and sequestration with solar energy and direct air capture.
Monitoring Marine Carbon Dioxide Removal: Quantitative Analysis of Indicators for Carbon Removed and Environmental Side-Effects
Abstract
Marine Carbon Dioxide Removal (mCDR) implementations require robust monitoring. The monitoring approaches in the literature are catered for specific use cases, hence, often dispersed, lacking consistency for each mCDR method. We surveyed the mCDR scientific literature to identify measurable indicators used across different ecosystems and methods for monitoring the carbon removed and environmental side-effects, and explore the main common challenges. Our results indicate that it is often difficult to establish direct linkage from the rates of chemical and biological changes to the amount of carbon removed and the magnitude of associated side-effects. The heterogeneity of marine biogeochemical and ecological processes together with the absence of regional boundaries represent the most common challenges. The lack of standardized indicators and monitoring procedures inhibits the verification, and hence, creates risk for further investment, prevents the entering of mCDRs into existing carbon certificate trading systems, and hinders the long term growth of this sector.
Morganti, T., Mengis, N., Oschlies, A. & Rehder, G. (2025) Monitoring Marine Carbon Dioxide Removal: Quantitative Analysis of Indicators for Carbon Removed and Environmental Side-Effects. ESS Open Archive.
Read the full paper here: Monitoring Marine Carbon Dioxide Removal: Quantitative Analysis of Indicators for Carbon Removed and Environmental Side-Effects I ESS Open Archive.
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Prey Dynamics as a Buffer: Enhancing Copepod Resilience to Ocean Alkalinity Enhancement
Abstract
Ocean alkalinity enhancement (OAE) aims to counteract climate change by increasing the ocean’s carbon storage capacity through the addition of alkaline substances into seawater. However, this process alters seawater chemistry, increasing total alkalinity (TA) and pH, which can directly influence marine organisms’ metabolic activities or indirectly impact them through changes in prey availability and quality. This study disentangled the OAE-driven factors that might influence zooplankton physiology. We assessed the direct effect of altered chemistry on the copepod, Temora longicornis, and the indirect effect through changes in the phytoplankton prey, Rhodomonas salina. We cultured the prey in OAE conditions and used it to feed copepods to investigate the indirect effect. We found that OAE negatively impacted prey growth but improved its nutritional quality, offsetting the direct negative impact of OAE on the copepod. These findings regarding OAE’s impact on prey-predator dynamics contribute to a deeper understanding of how OAE might influence zooplankton communities.
Bhaumik, A., Faucher, G., Henning, M., Meunier, C. & Boersma, M. (2025) Prey Dynamics as a Buffer: Enhancing Copepod Resilience to Ocean Alkalinity Enhancement. Environmental Research Letters.
Read the full paper here: Prey Dynamics as a Buffer: Enhancing Copepod Resilience to Ocean Alkalinity Enhancement I Environmental Research Letters
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Land Conversions not Climate Effects are the Dominant Indirect Consequence of Sun-Driven CO2 Capture, Conversion and Sequestration
Abstract
Removing carbon dioxide (CO2) from the atmosphere is required for mitigating climate change. Large-scale direct air capture combined with injecting CO2 into geological formations could retain carbon long-term, but demands a substantial amount of energy, pipeline infrastructure, and suitable sites for gaseous storage. Here, we study Earth system impacts of modular, sun-powered process chains, which combine direct air capture with (electro)chemical conversion of the captured CO2 into liquid or solid sink products and subsequent product storage (sDACCCS). Drawing on a novel explicit representation of CO2 removal in a state-of-the-art Earth system model, we find that these process chains can be renewably powered and have minimal implications for the climate and carbon cycle. However, to stabilize the planetary temperature two degrees above pre-industrial levels, CO2 capturing, conversion, and associated energy harvest demand up to 0.46% of the global land area in a high-efficiency scenario. This global land footprint increases to 2.82% when assuming present-day technology and pushing to the bounds of removal. Mitigating historical emission burdens within individual countries in this high-removal scenario requires converting an area equivalent to 40% of the European Union’s agricultural land. Scenarios assuming successful technological development could halve this environmental burden, but it is uncertain to what degree they could materialize. Therefore, ambitious decarbonization is vital to reduce the risk of land use conflicts if efficiencies remain lower than expected.
Moritz, A., Kleinen, T., Matthias, M. & Rehfeld, K. (2024) Land Conversions not Climate Effects are the Dominant Indirect Consequence of Sun-Driven CO2 Capture, Conversion and Sequestration. Environmental Research Letters.
Read the full paper here: Land Conversions not Climate Effects are the Dominant Indirect Consequence of Sun-Driven CO2 Capture, Conversion and Sequestration I Environmental Research Letters
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Carbon Removal Efficiency and Energy Requirement of Engineered Carbon Removal Technologies
Abstract
To ensure carbon negativity, processes that achieve carbon dioxide removal (CDR) from the atmosphere must consider lifecycle emissions and energy requirements across the entire system. We conduct a harmonized lifecycle greenhouse gas assessment to compare the carbon removal efficiency and total energy required for twelve engineered carbon removal technologies. The goal of this comparison is to enable the assessment of diverse engineered carbon removal approaches on a consistent basis. Biomass-based CDR approaches generally maintain higher carbon removal efficiency than direct air capture (DAC) and, to a lesser extent, enhanced rock weathering (ERW) due to the high concentration of carbon within the biomass and the relatively low energy requirements for processing the biomass for removal. Nevertheless, there is high variance in CDR approaches, as some biomass conversion processes (e.g., pyrolysis for biochar or gasification for fuels) exhibit high, yet variable, carbon losses, while DAC and ERW can utilize low-carbon energy inputs for more efficient removal. Regarding energy use, ERW and biomass-based approaches generally require less energy than DAC, but biomass approaches again exhibit more variation. Displacement of products, when included, increases the total climate benefits of biomass used for bioenergy with carbon capture and storage (BECCS) and biochar. These two measures are intuitive metrics to guide allocation of scarce resources amongst potentially competing uses of biomass and low-carbon energy.
Sanchez, D., Psarras, P., Murnen, H. & Rogers, B. (2025) Carbon Removal Efficiency and Energy Requirement of Engineered Carbon Removal Technologies. Royal Society of Chemistry
Read the full paper here: Carbon Removal Efficiency and Energy Requirement of Engineered Carbon Removal Technologies I Royal Society of Chemistry
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Electrochemical Approaches for CO2 Point Source, Direct Air and Seawater Capture: Identifying Opportunities and Synergies
Abstract
The world is increasingly facing the direct effects of climate change triggering warnings of a crisis for the healthy existence of humankind. The dominant driver of the climate emergency is the historical and continued accumulation of atmospheric CO2 altering net radiative forcing on the planet. To address this global issue, understanding the core chemistry of CO2 manipulation in the atmosphere and proximally in the oceans is crucial, to offer a direct partial solution for emissions handling through negative emissions technologies. Many technologies have been proposed to develop a strategic and economic solution for carbon capture, storage, and utilization. In this paper, we review recent advances in technologies proposed for carbon capture and release via electrochemical process for point source/flue gas, direct air capture (DAC), and ocean/seawater capture. Electrochemical approaches to carbon capture are favorable in terms of reaction conditions, their ability to be incorporated into transformation processes, modularity, low relative carbon footprint, and compatibility with the availability of renewable electricity sources. We offer a critical comparative analysis of land- and ocean-based capture technologies to help guide future research and innovation.
Nisa, M., Ishaq, H. & Crawford, C. (2025) Electrochemical Approaches for CO2 Point Source, Direct Air and Seawater Capture: Identifying Opportunities and Synergies. Environmental Science and Pollution Research.
Read the full paper here: Electrochemical Approaches for CO2 Point Source, Direct Air and Seawater Capture: Identifying Opportunities and Synergies I Environmental Science and Pollution Research.