This week’s publication highlights cover issues related to a wide range of CDR methods such as enhanced weathering modelling, direct air capture, biochar and bioenergy with carbon capture and storage.
Advancing Enhanced Weathering Modeling in Soils: Critical Comparison with Experimental Data
Abstract
Enhanced weathering (EW) is a promising strategy to remove atmospheric CO2 by amending agricultural and forestry soils with ground silicate rocks. However, current model-based EW assessments face large uncertainties stemming from the intricate interplay among soil processes, compounded by the absence of a detailed comparison with available observational data. Here, we address this critical gap by first advancing a dynamic, ecohydrological, and biogeochemical Soil Model for Enhanced Weathering (SMEW). We then conduct a hierarchical model-experiment comparison with four experimental data sets of increasing complexity, from simple closed incubation systems to open mesocosm experiments. The comparison demonstrates SMEW’s ability to capture the dynamics of primary variables, including soil moisture, alkalinity, and inorganic carbon. The comparison also reveals that weathering rates are consistently lower than traditionally assumed by up to two orders of magnitude. We finally discuss the implications for carbon removal scenarios and avenues for further theoretical and experimental explorations.
Bertagni, M. et al. (2024) Advancing Enhanced Weathering Modeling in Soils: Critical Comparison with Experimental Data. 17 (1) Advancing Earth and Space Sciences.
Read the full paper here: Advancing Enhanced Weathering Modeling in Soils: Critical Comparison with Experimental Data I Advancing Earth and Space Sciences.
Preserving Carbon Dioxide Removal to Serve Critical Needs
Abstract
Carbon dioxide removal (CDR) is critical to most net-zero pathways, especially given challenges due to slow decarbonization, hard-to-abate (H2A) economic activities and non-CO2 GHGs. However, land-based CDR, which is the most widely deployed currently and in future projections, requires extensive land and water. Here we examine least-cost 1.5 °C overshoot pathways, finding that 78 of 81 scenarios would require all available sustainable CDR to compensate for H2A emissions and overshoot. Use of CDR to compensate for emissions from easier-to-decarbonize sectors such as electricity would leave less available to compensate for H2A emissions, increasing system-wide costs of net zero or rendering such goals impossible. Such usage, however, is allowed in many jurisdictions and is widespread in voluntary markets. We suggest that rapidly transitioning CDR usage to exclusively compensate for H2A emissions and overshoot is required to prevent lower costs for near-term actors leading to larger long-term system-wide costs.
Shindell, D. and Rogelj, J. (2025) Preserving Carbon Dioxide Removal to Serve Critical Needs. Nature.
Read the full paper here: Preserving Carbon Dioxide Removal to Serve Critical Needs I Nature
Direct Air Capture of CO2 for Solar Fuel Production in Flow
Abstract
Direct air capture is an emerging technology to decrease atmospheric CO2 levels, but it is currently costly and the long-term consequences of CO2 storage are uncertain. An alternative approach is to utilize atmospheric CO2 on-site to produce value-added renewable fuels, but current CO2 utilization technologies predominantly require a concentrated CO2 feed or high temperature. Here we report a gas-phase dual-bed direct air carbon capture and utilization flow reactor that produces syngas (CO + H2) through on-site utilization of air-captured CO2 using light without requiring high temperature or pressure. The reactor consists of a bed of solid silica-amine adsorbent to capture aerobic CO2 and produce CO2-free air; concentrated light is used to release the captured CO2 and convert it to syngas over a bed of a silica/alumina-titania-cobalt bis(terpyridine) molecular–semiconductor photocatalyst. We use the oxidation of depolymerized poly(ethylene terephthalate) plastics as the counter-reaction. We envision this technology to operate in a diurnal fashion where CO2 is captured during night-time and converted to syngas under concentrated sunlight during the day.
Kar, S. et al. (2025) Direct Air Capture of CO2 for Solar Fuel Production in Flow. Nature. 1-20.
Read the full paper here: Direct Air Capture of CO2 for Solar Fuel Production in Flow I Nature.
Assessment of Technologies and Economics for Carbon Dioxide Removal from a Portfolio Perspective
Abstract
Carbon dioxide removal (CDR) is essential to achieve ambitious climate goals limiting global warming to less than 1.5°C, and likely for achieving the 1.5°C target. This study addresses the need for diverse CDR portfolios and introduces the LUT-CDR tool, which assesses CDR technology portfolios aligned with hypothetical societal preferences. Six scenarios are described, considering global deployment limitations, techno-economic factors, area requirements, technology readiness, and storage security for various CDR options. The results suggest the feasibility of large-scale CDR, potentially removing 500–1750 GtCO2 by 2100 to meet the set climate targets. For a 1.0°C climate goal, CDR portfolios necessitate 12.0–37.5% more primary energy compared to a scenario without CDR. Remarkably, funding a 1.0°C target requires only 0.42–0.65% of the projected global gross domestic product. Bioenergy carbon capture and sequestration and rainfall-based afforestation play limited roles, while secure sequestration of captured CO2 via direct air capture, electricity-based carbon sequestration, and desalination-based afforestation emerge as more promising options. The study offers crucial techno-economic parameters for implementing CDR options in future energy-industry-CDR system analyses and demonstrates the tool’s flexibility through alternative assumptions. It also discusses limitations, sensitivities, potential trade-offs, and outlines options for future research in the area of large-scale CDR.
Muhlbauer, A. et al. (2025) Assessment of Technologies and Economics for Carbon Dioxide Removal from a Portfolio Perspective. International Journal of Greenhouse Gas Control 141 (104297) 1-21.
Read the full paper here: Assessment of Technologies and Economics for Carbon Dioxide Removal from a Portfolio Perspective I International Journal of Greenhouse Gas Control
Co-deploying Biochar and Bioenergy with Carbon Capture and Storage Improves Cost-Effectiveness and Sustainability of China’s Carbon Neutrality
Abstract
Committed to carbon neutrality by 2060, China must deploy carbon dioxide removal (CDR) alongside deep mitigation strategies to offset residual emissions from hard-to-abate sectors. Bioenergy with carbon capture and storage (BECCS) becomes a leading CDR method, leveraging bioenergy technologies to remove CO2 while producing carbon-neutral energy. However, BECCS relies on geological CO2 storage capacity and risks soil degradation from large-scale energy crop cultivation. Biochar produced from biomass offers a complementary solution, sequestering CO2 for extended periods with co-benefits like improved soil health, but may face biomass availability constraints. An imperative yet unanswered question is whether a co-deployment of BECCS and biochar can feasibly enhance China’s CDR potential without introducing sustainability trade-offs. We show that BECCS + biochar can cost-effectively increase CDR by 15%–400%, particularly in regions lacking CO2 transport networks. Our work suggests a promising CDR deployment strategy for China to meet the carbon neutrality target sustainably and efficiently.
Deng, X. et al. (2025) Co-deploying Biochar and Bioenergy with Carbon Capture and Storage Improves Cost-Effectiveness and Sustainability of China’s Carbon Neutrality. 8 (1) One Earth.
Read the full paper: Co-deploying Biochar and Bioenergy with Carbon Capture and Storage Improves Cost-Effectiveness and Sustainability of China’s Carbon Neutrality I One Earth.