This week’s publication highlights relate to biomass, ocean alkalinity enhancement, cdr potential of vegetation and agricultural CDR.
Enhancing Biomass-Fueled Oxy-Combustion Bioenergy with Carbon Capture and Storage through Electrolysis-Derived Oxygen
Abstract
Transitioning from fossil-based power generation to carbon-neutral or negative-emission solutions is essential to mitigate climate change. This study investigates the integration of biomass power plants with carbon capture technology, focusing on utilizing byproduct oxygen from renewable-powered water electrolysis to reduce dependency on conventional air separation units (ASUs). Oxy-combustion enhances fuel combustion property and simplifies CO2 capture, but the reliance on ASUs to obtain high-purity oxygen often introduces substantial capital and operational costs. Here, the use of side-produced O2 from green hydrogen production is proposed to supply the oxygen required for oxy-combustion in a 10 MWe subcritical circulating fluidized-bed (CFB) biomass power plant. Through comprehensive process simulation and performance analysis, traditional ASU-based configurations are compared with electrolysis-derived oxygen systems. Results show that substituting ASU-generated O2 with byproduct O2 can increase net efficiency from 32.5 % to 38.4 % and lower the levelized cost of electricity (LCOE) from 176.9 USD/MWh to 140.4 USD/MWh. This approach significantly reduces capital investments and operational expenditures while improving environmental performance. By leveraging renewable electrolytic oxygen, bioenergy with carbon capture and storage (BECCS) technology is advanced, positioning it as a more economically viable and sustainable transitional solution toward a carbon-neutral energy landscape.
Mun, T. and Ryu, K. (2025) Enhancing Biomass-Fueled Oxy-Combustion Bioenergy with Carbon Capture and Storage through Electrolysis-Derived Oxygen 339 (139022) Energy.
Read the full paper here: Enhancing Biomass-Fueled Oxy-Combustion Bioenergy with Carbon Capture and Storage through Electrolysis-Derived Oxygen I Energy.
Assessing Biomass Carbon Dioxide Removal Supply Chains: System Modelling and Economic Assessment
Abstract
Pyrolytic conversion of biomass is used to produce biochar—a stable form of solid carbon storage that is becoming an effective carbon dioxide removal method—and to produce sustainable liquid hydrocarbons that can contribute to sustainable shipping and aviation. This study aims to assess the economics of biochar carbon removal (BCR) across the entire supply chain. A mixed-integer nonlinear programming model is developed to determine the optimal carbon credit, a break-even carbon dioxide removal outcome at which a BCR system achieves a zero net present value. The model is applied to two case studies using available paper sludge and sewage sludge from 32 European countries, where biomass is converted into biochar and biofuel using the thermo-catalytic reforming process. Our results show that the necessary carbon credits are lowest under the partial aggregation of biomass and optimally located conversion plants, compared to fully centralized or decentralized approaches. The results of the optimization model for two case studies reveal that, with a carbon credit of 106 €/t-CO2, all plants utilizing paper sludge could operate cost-effectively, with most remaining economically viable even without carbon credit incentives. In contrast, BCR systems based on sewage sludge exhibit significantly lower profitability; over 90 % of plants require carbon credit to remain economically viable, and more than half need carbon credits at prices exceeding 150 €/t-CO2.
Grimm, V. et al. (2026) Assessing Biomass Carbon Dioxide Removal Supply Chains: System Modelling and Economic Assessment 226 (116298) Renewable and Sustainable Energy Reviews.
Read the full paper here: Assessing Biomass Carbon Dioxide Removal Supply Chains: System Modelling and Economic Assessment I Renewable and Sustainable Energy Reviews.
Global Carbonate Chemistry Gradients Reveal a Negative Feedback Feedback on Ocean Alkalinity Enhancement
Abstract
Ocean alkalinity enhancement is a widely considered approach for marine CO2 removal. Alkalinity enhancement sequesters atmospheric CO2 by shifting the seawater carbonate equilibrium from CO2 towards bicarbonate and carbonate ions. Such re-equilibration has been hypothesized to benefit calcifying organisms, whose increased calcification could strongly reduce the efficiency of alkalinity enhancement. Here we use global ocean satellite data to constrain the sensitivity of coccolithophores—an important group of calcifying phytoplankton—to natural gradients of seawater carbonate chemistry. We show that the ratio of particulate inorganic to particulate organic carbon, reflecting the balance of calcifying versus non-calcifying phytoplankton, is influenced by environmental drivers, including nutrient stoichiometry and carbon substrate within biogeochemical provinces. Across biogeochemical provinces, however, this ratio persistently correlates with carbonate chemistry through combined influences of carbon substrate availability and proton inhibition of calcification. We estimate that extreme alkalinity enhancement may promote the proliferation of coccolithophores, thereby reducing the CO2 removal potential of ocean alkalinity enhancement by 2–29% by 2100. However, less extreme alkalinity enhancement may only mitigate for adverse acidification effects on coccolithophores. Our findings demonstrate the importance of considering large-scale biogeochemical feedbacks when evaluating the efficiency of ocean alkalinity enhancement.
Lehmann, N. and Bach, L. (2025) Global Carbonate Chemistry Gradients Reveal a Negative Feedback Feedback on Ocean Alkalinity Enhancement 18 Nature Geoscience.
Read the full paper here: Global Carbonate Chemistry Gradients Reveal a Negative Feedback Feedback on Ocean Alkalinity Enhancement I Nature Geoscience.
The Carbon Sequestration Potential of Vegetation over the Tibetan Plateau
Abstract
Ecosystems on the Tibetan Plateau (TP) are strategically important natural resources of China. However, whether the regional vegetation would continue to sequester more carbon over the coming decades and how much stocks could be delivered through improved management are not clear. In this study, the vegetation carbon stocks in 2020 (VCS2020) and carbon sequestration potential (VCSpot) were evaluated by integrating 2040 field-plots data at the plant community level and models (Forest Carbon Sequestration Model and Random Forest Model). Results showed that the VCS2020 was 1965.6 Tg, with 78.5 % stored in forests, 9.7 % in shrubs, and 11.7 % in grasslands. The VCSpot was projected to be 458.3 Tg C from 2020 to 2060, with an average rate of 11.5 Tg C yr−1, and existing forests, afforestation, and grasslands accounting for 79.3 %, 18.5 %, and 2.2 %, respectively. The rate of VCSpot (RVCS) from afforestation is increasing gradually and becomes a substantial contributor of VCSpot from 2020 to 2060, especially in the southeastern parts of the TP. The VCSpot would offset 31.0 % of anthropogenic carbon emissions over the TP during 2020–2060. Therefore, this study proposes that the implementation of appropriate regulation for existing forests and scientific use of suitable areas for afforestation could help achieving the carbon neutrality target at the regional and even national scale in the future.
Cai, W. et al. (2025) The Carbon Sequestration Potential of Vegetation over the Tibetan Plateau 207 (114937) Renewable and Sustainable Energy Reviews.
Read the full paper here: The Carbon Sequestration Potential of Vegetation over the Tibetan Plateau I Renewable and Sustainable Energy Reviews.
Inorganic Carbon Should Be Considered for Carbon Sequestration in Agricultural Soils
Abstract
Improved agricultural practices that restore soil organic carbon (SOC) are recognized as climate solutions, whereas soil inorganic carbon (SIC) is ignored nearly in all practices. Here, we meta-analyzed the joint response of SOC and SIC to six common agricultural practices, i.e., reduced tillage, irrigation, fertilization, residue utilization, reclamation, and restoration. The results demonstrated that the most agricultural practices strongly increased SOC, whereas SIC was less sensitive. SOC and SIC increased synergistically by following practices: Irrigation, biochar application, and improved reclamation. However, “trade-offs” between SOC and SIC due to mineral fertilizer application and restoration to forestland may partly offset soil carbon sequestration. The magnitude of SOC changes decreased with increasing depth, and deep SOC was still responsive to agricultural practices. In contrast, SIC loss occurred mainly in the topsoil, while increases were mainly in the deep soil. By optimizing agricultural practices, we estimated the global potential of carbon sequestration in soil at 1.5 Gt yr.−1 (95% confidence interval: 0.3–2.8), with SOC contributing 1.4 Gt yr.−1, while SIC contributed less (0.1 Gt yr.−1) due to its losses under some practices. This potential is equivalent to 16% of global fossil fuel emissions. Concluding, this study highlights the potential contribution of SIC in enhancing the integrity of soil-based climate solutions, broadening the scope of carbon management in mitigating climate change.
Liao, Y. et al. (2025) Inorganic Carbon Should Be Considered for Carbon Sequestration in Agricultural Soils 31 (4) Global Change Biology.
Read the full paper here: Inorganic Carbon Should Be Considered for Carbon Sequestration in Agricultural Soils I Global Change Biology.