CO2-removal News

Peer-reviewed Publications

PNAS – Conrad-Rooney et al. (2025): Declining winter snowpack offsets carbon storage enhancement from growing season warming in northern temperate forest ecosystems

Emerson Conrad-Rooney, Andrew B. Reinmann and Pamela H. Templer, IN: Proceedings of the National Academy of Sciences (PNAS), https://doi.org/10.1073/pnas.2412873122

Northeastern US temperate forests are currently net carbon (C) sinks and play an important role offsetting anthropogenic C emissions, but projected climatic changes, including increased temperatures and decreased winter snowpack, may influence this C sink over the next century. Past studies show that growing season warming increases forest C storage through greater soil nutrient availability that contributes to greater rates of net photosynthesis, while reduced winter snowpack induces soil freeze/thaw cycles that reduce tree root vitality, nutrient uptake, and forest C storage. The year-round effects of climate change on this C sink are not well understood. The authors report here decade-long results from the Climate Change Across Seasons Experiment (CCASE) at the Hubbard Brook Experimental Forest, which determines the combined effects of growing season warming and a smaller winter snowpack on C storage in northern temperate forests.

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Peer-reviewed Publications

Sun et al. (2025): Improvement of mechanical properties and carbon sequestration effect of carbide slag-carbonization curing on cement-based materials

Dao-Lin Sun, Yonghong Miao, Jianguo Zhu, Peng Wang, Yulong Zheng, Kaiwei Lu and Gui-Yu Zhang, IN: Journal of Building Engineering, https://doi.org/10.1016/j.jobe.2025.113439

Using industrial solid waste calcium carbide slag (CCS) to replace part of cement clinker and combining it with carbonization curing technology is an important way to achieve carbon reduction and resource recycling. This paper studies the effect of different CCS dosages on the performance of ordinary Portland cement (OPC) in combination with carbonation curing, and explains the synergistic effect of its mechanical properties, microstructural changes and carbon fixation capacity.

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Peer-reviewed Publications

Sartzetakis et al. (2025): Temporal trade-offs in climate benefits from carbon dioxide removal—insights from wetland restoration and assessment metrics

Stavroula S. Sartzetakis, Tianyi Sun, Yangyang Xu, Emily A. Ury, Ilissa B. Ocko and Brian Buma, IN: Environmental Research Letters, https://doi.org/10.1088/1748-9326/adeb9d

CDR measures may unintentionally increase emissions of other climate forcers. If emissions of potent short-lived climate forcers (like methane) are increased, the CDR mechanism could potentially worsen climate change in the near-term despite benefiting the climate in the long-term. This temporal trade-off can be easily overlooked when employing the standard climate metric used for assessments—carbon dioxide equivalent (CO₂e) using a 100 year global warming potential (GWP)—because it solely conveys the long-term warming impacts of a pulse of emissions. A more sophisticated assessment method is needed to reveal potential temporal trade-offs in climate benefits—important information for effective decision making. In this study, the authors compare three climate impact assessment approaches of increasing complexity to evaluate temporal trade-offs in climate benefits from CDR strategies: (1) the standard CO₂e using GWP approach with both 20 and 100 year time horizons (GWP20 and GWP100, respectively, or dual-valued CO₂e); (2) a variation of GWP that considers the climate impact of continuous emissions over time (known as technology warming potential (TWP)); and (3) reduced complexity climate models. They use wetland restoration as a case study because studies have shown that it may remove carbon dioxide from the atmosphere, while also increasing methane emissions.

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Peer-reviewed Publications

Sloterdijk et al. (2025): Future scenarios of global fisheries and ocean alkalinity enhancement under socio-economic and climate pathways

Hans Sloterdijk, Caroline Grünhagen, Rudi Voss, Patricia Grasse, David P. Keller, Linda Kleemann, Lotta Clara Kluger, Kira Lancker, Wilfried Rickels, Ulf Riebesell, Renato Salvatteci, Andreas Oschlies, Jörn O. Schmidt, Natascha Oppelt, Katrin Rehdanz and Marie-Catherine Riekhof, IN: Earth’s Future, https://doi.org/10.1029/2024EF005478

Ocean alkalinity enhancement (OAE) is one strategy, designed to strengthen the ocean’s natural carbon sink, reduce atmospheric CO₂, and mitigate ocean acidification. However, its implications for fisheries, critical for food security and livelihoods, remain uncertain. This study examines the interplay between global fisheries, OAE, and different future socioeconomic and climatic conditions, using the Shared Socioeconomic Pathways (SSPs) and Representative Concentration Pathways framework. The authors explore how global fisheries and OAE could evolve under three combined scenarios: SSP1-2.6 (sustainability-focused), SSP3-7.0 (regional rivalry), and SSP5-8.5 (high fossil fuel dependency). By integrating ecological, economic, societal, and technological perspectives, they develop scenario narratives and quantify key bio-economic parameters, including technological progress, fishing costs, fisheries management, marine aquaculture, and ecosystem carrying capacity.

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Peer-reviewed Publications

Tian et al. (2025): Stability of alkalinity in the land-ocean transition zone: a geochemical CDR perspective for the Elbe River, Germany

Mingyang Tian, Jens Hartmann, Niels Suitner, Thorben Amann, Stephan Kempe, Carl Lim and Charly Andre Moras, IN: Environmental Research Letters, https://doi.org/10.1088/1748-9326/adeeab

Carbon dioxide removal (CDR) strategies like enhanced weathering and river/ocean alkalinity enhancement have been suggested to increase alkalinity in rivers, coastal areas, and eventually oceans. The effectiveness and sustainability of these CDR approaches depend on the persistence of added alkalinity, since exceeding certain Ω-thresholds for a given water composition may lead to carbonates formation, causing the loss of previously added alkalinity. In this research, stability of alkalinity was tested using incubation experiments with Elbe estuary freshwater from two seasons (March and August).

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Peer-reviewed Publications

Rizvi et al. (2025): Carbon-negative process integration: Techno-economic framework for biomass-blend bio-energy carbon capture and storage polygeneration with high-value co-product streams

Syed Muhammad Mustafa Rizvi, Bilal Kazmi, Syed Ali Ammar Taqvi and AbdulAziz AlGhamdi, IN: Biomass and Bioenergy, https://doi.org/10.1016/j.biombioe.2025.108145

This study investigates a novel integrated system combining waste management and sustainable energy production through co-gasification of municipal solid waste (MSW) blends with various feedstocks: paper mill sludge, plastic waste, and food waste. Techno-economic assessment of producing value-added products while minimizing carbon emissions through syngas generation and subsequent conversion to biofuels. The process analysis evaluates syngas composition under varying steam-to-biomass ratios and gasifier temperatures (500–1200 °C), achieving optimal H₂ yields with MSW-food waste blends. Cryogenic separation utilized for high CO₂ capture efficiency (95%+) with purities reaching 0.9979, particularly effective for MSW-food waste feedstock.

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Peer-reviewed Publications

Hooper et al. (2025): Removal of dissolved inorganic carbon from seawater for climate change mitigation – understanding the potential marine ecosystem impacts

Guy Hooper, Helen S. Findlay, Thomas George Bell, Rod W. Wilson and Paul Halloran, IN: Frontiers in Climate, https://doi.org/10.3389/fclim.2025.1528951

Electrochemical ‘Direct Ocean Carbon Capture and Storage’ (DOCCS) is a marine carbon dioxide removal (mCDR) method that removes atmospheric CO₂ by releasing low-carbon seawater into the surface ocean, where it re-equilibrates with the atmosphere and stores atmospheric CO₂. At the point of release, DOCCS discharge has low concentrations of dissolved inorganic carbon (DIC) and high pH, potentially causing unintended marine environmental impacts; however, its chemistry moves progressively towards that of ambient seawater as it dilutes and re-equilibrates with the atmosphere. To date, there are no published studies that investigate the impact of DOCCS discharge on marine ecosystems. Research from relevant analogues, where biological responses to low-DIC and/or high-pH seawater are investigated, provides some insight into potential DOCCS impacts. Despite this, significant evidence gaps remain. These evidence gaps are discussed alongside DOCCS-specific recommendations for future environmental impact research. Understanding the potential risks/benefits to marine ecosystems from discharge of low-DIC and high-pH seawater is critical to: i) support licensing applications; ii) develop any necessary mitigating actions; iii) determine the net benefit of mCDR approaches; and iv) stimulate informed public discourse about the acceptability of such approaches.

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Peer-reviewed Publications

Baeyens et al. (2025): Prevalence of multi-micronutrient limitation of phytoplankton growth in the Southern Ocean

Willy Baeyens, Yue Gao, Eline De Bodt, Nils Van Oostende, Hélène Planquette, Hein de Baar, Xabier Irigoien, Rob Middag and Philippe Van den Bril, IN: One Earth, https://doi.org/10.1016/j.oneear.2025.101354

The mitigation of the ongoing global waming might be possible if phytoplankton biomass is increased in the ocean, as this will remove additional atmospheric CO₂. In the Southern Ocean, Fe is a well-known growth-limiting element, but the role of the other micronutrients remains very unclear. The authors aim is to describe the evolution of each nutrient in the Southern Ocean throughout the year and to identify nutrients that limit phytoplankton growth. Therefore, they created a model that calculates nutrient consumption rates and available nutrient pools, fueled by deep winter mixing and diapycnal supply.

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Peer-reviewed Publications

Shehzad et al. (2025): Dynamic modeling and optimal control schemes for an offshore-wind powered direct air capture system with energy storage options

Muhammad Faisal Shehzad, Haris Ishaq, Curran Crawfrod, IN: Science of The Total Environment, https://doi.org/10.1016/j.scitotenv.2025.179537

This paper proposes an offshore-wind energy powered atmospheric CO₂ capture system. A key challenge is the variable nature of renewable wind-energy to meet direct air capture (DAC) system power requirements. One solution to mitigate this challenge is to integrate the wind-CO₂ capture system with advanced Energy Storage Systems (ESS). Previous research in this direction has been carried out, however the optimal ESS is still an open question due to the limitations and constraints of each ESS technology. The constraints include concerns over degradation, ESS response times, and overall costs. This paper proposes an advanced energy management strategy (EMS) within the CO₂ capture system to address the outlined problems. It presents a dynamic model for offshore-wind direct air capture of CO₂ system coupled with a battery-based energy storage system with the objective of maximizing CO₂ removal from air while fulfilling the overall system operational constraints and dynamics. More specifically, the proposed model investigates the flexibility of the CO₂ capture system with respect to wind power supply in different seasons. The DAC models proposed in this research consists of a three state automaton, namely: OFF, Adsorption, and Desorption which handle the three operational states of the proposed CO₂ capture system. In order to maximally utilize wind power availability, each operational state of the proposed model is considered as a separate load and dispatched separately. The proposed approach is then compared and analyzed by scheduling the system as a whole. Numerical results illustrate the feasibility of powering CO₂ capture system via variable wind power.

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Peer-reviewed Publications

Nature – Hassan et al. (2025): A Membraneless Electrochemically Mediated Amine Regeneration for Carbon Capture

Ahmad Hassan, Mohsen Afshari & Mim Rahimi, IN: Nature Communications, https://doi.org/10.1038/s41467-025-61525-3

Among electrochemical carbon captures (ECCs), electrochemically mediated amine regeneration (EMAR) reached higher technology readiness levels, moving from small-scale laboratory studies toward pilot-scale implementations. Previous EMAR systems rely on ion-selective membranes, which contribute significantly to the cost and present challenges for long-term operation. This study presents a membraneless EMAR system by fundamentally redesigning the process configuration and using gas diffusion electrodes (GDEs) as both the anode and cathode. This setup eliminates the membrane and the need for additional equipment such as the absorption column, flash tank, and pumps, significantly reducing the process footprint and simplifying the flow diagram. Two GDE configurations, mesh-attached and electrodeposited, are tested and compared in terms of CO₂ removal efficiency, current density, and energy consumption.

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