This week’s publication highlights CDR methods such as direct air capture, biochar, biomass and forestation.
Direct Air Capture of CO2 in an Electrochemical Hybrid Flow Cell with a Spatially Isolated Phenazine Electrode
Abstract
CO2 capture based on a pH swing driven electrically through the reversible proton-coupled electron transfer of organic molecules could be powered entirely by clean electricity. A major technical challenge is the reversible chemical oxidation of the reduced organics by atmospheric O2, which can lower energy efficiency and capture capacity. Here we report the development of a hybrid phenazine flow cell system that uses a pH-swing direct air capture (DAC) process, utilizing redox-active cyclic poly(phenazine sulfide) fabricated solid electrodes. The system maintains a separation between the air and the O2-sensitive reduced phenazine, enabling stable and effective CO2 capture from gas mixtures containing O2. This flow cell demonstrated substantial oxygen compatibility, exhibiting a coulombic efficiency of 99% and requiring only 73 kJ mol−1 CO2 for simulated flue gas and 104 kJ mol−1 CO2 for DAC. The strategy of isolating vulnerable species offers an efficient pathway for DAC and may be broadly applicable to avoiding undesirable side reactions in other electrochemical devices.
Jin, X. et al. (2025) Direct Air Capture of CO2 in an Electrochemical Hybrid Flow Cell with a Spatially Isolated Phenazine Electrode 10 Nature Energy.
Read the full paper here: Direct Air Capture of CO2 in an Electrochemical Hybrid Flow Cell with a Spatially Isolated Phenazine Electrode I Nature Energy.
Global Insights into Biochar: Production, Sustainable Applications and Market Dynamics
Abstract
Biochar, a carbon-rich product developed from biomass via thermochemical techniques, has attracted international recognition for its multifaceted prospects as a sustainable global environmental solution. This review article offers an extensive analysis of biochar production methods, industrial applications and market dynamics, with a special emphasis on India. It seeks to bridge the gap between technical advances and market prospects, highlighting the role of biochar in sustainable development and circular economy. The review article examines key questions, including: How do various biochar production techniques compare with regards to cost, efficiency and environmental impact? What are the challenges and chances of biochar implementation in various industries? How might India’s emerging market of biochar contribute to global sustainability aims? This review uniquely combines the technical aspects of biochar production with an in-depth market analysis, highlighting on India’s untapped potential in the global biochar market. The review emphasizes the efficacy of advanced biochar production techniques, including hydrothermal carbonization and microwave-assisted pyrolysis, while recognizing challenges like energy intensity and feedstock variability. The versatility of biochar is discussed through its application in various industries such as wastewater treatment, agriculture, electronics and construction. Significant findings encompass its capacity for carbon sequestration, enhanced soil productivity, and incorporation into sustainable construction materials. By acknowledging these components, this review can help researchers, policymakers, and industry stakeholders to improve biochar technology and increase its market potential globally, with particular emphasis on India.
Singh, R. et al. (2025) Global Insights into Biochar: Production, Sustainable Applications and Market Dynamics 194 (107663) Biomass and Bioenergy.
Read the full paper here: Global Insights into Biochar: Production, Sustainable Applications and Market Dynamics I Biomass and Bioenergy.
Use of Biomass-Derived Biochar as a Sustainable Material for Carbon Sequestration in Soil: Recent Advancements and Future Perspectives
Abstract
The application of biomass-derived carbon materials (e.g., biochar) into soil is considered as an attractive and sustainable strategy to enhance carbon sequestration in soil and to mitigate climate change. Our comprehensive literature analysis shows that the carbon sequestration potential of biochar in soil systems varies between 0.7 and 1.8 Gt CO2-C(eq)/year. Biochar with high stability and C/N ratios is effective to achieve significant carbon sequestration in soil. Furthermore, carbon sequestration is usually favourable at high biochar application rate in soil with high porosity and alkaline pH (>7.5). The dominant bacterial communities enriched in the biochar-amended soil include Proteobacteria and Acidobacteria, while Ascomycota dominates the fungal communities. The impact of biochar amendment on soil microbial biomass and communities depends on the biochar particle size, porosity and application rate. Life cycle assessment (LCA) of biochar-amended soil reveals that biochar produced from waste biomass is found to be environmentally friendly with the acceptable level of economic feasibility in terms of large-scale applications. The recommended future research directions to seek practical applications of biochar amendment in soil include (1) development of biochar-microbe co-engineering strategies to stabilize labile carbon fractions in soil, (2) exploration of machine learning tools to optimize biochar properties for adoption of biochar treatment under region-specific soil conditions, and (3) standardization of carbon accounting methodologies to address and resolve discrepancies in LCA studies. We believe that this comprehensive review would help for development of novel biochar to achieve optimum carbon sequestration efficiency in soil and to develop practical climate change mitigation strategies.
Biswal, B. et al. (2025) Use of Biomass-Derived Biochar as a Sustainable Material for Carbon Sequestration in Soil: Recent Advancements and Future Perspectives 3 (26) Materials Sustainability.
Read the full paper here: Use of Biomass-Derived Biochar as a Sustainable Material for Carbon Sequestration in Soil: Recent Advancements and Future Perspectives I Materials Sustainability.
Half of Land Use Carbon Emissions in Southeast Asia Can be Mitigated through Peat Swamp Forest and Mangrove Conservation and Restoration
Abstract
Southeast Asia (SEA) contributes approximately one-third of global land-use change carbon emissions, a substantial yet highly uncertain part of which is from anthropogenically-modified peat swamp forests (PSFs) and mangroves. Here, we report that between 2001–2022 land-use change impacting PSFs and mangroves in SEA generate approximately 691.8±97.2 teragrams of CO2 equivalent emissions annually (TgCO2eyr−1) or 48% of region’s land-use change emissions, and carbon removal through secondary regrowth of −16.3 ± 2.0 TgCO2eyr−1. Indonesia (73%), Malaysia (14%), Myanmar (7%), and Vietnam (2%) combined accounted for over 90% of regional emissions from these sources. Consequently, great potential exists for emissions reduction through PSFs and mangroves conservation. Moreover, restoring degraded PSFs and mangroves could provide an additional annual mitigation potential of 94.4 ± 7.4 TgCO2eyr−1. Although peatlands and mangroves occupy only 5.4% of SEA land area, restoring and protecting these carbon-dense ecosystems can contribute substantially to climate change mitigation, while maintaining valuable ecosystem services, livelihoods and biodiversity.
Sasmito, S. et al. (2025) Half of Land Use Carbon Emissions in Southeast Asia Can be Mitigated through Peat Swamp Forest and Mangrove Conservation and Restoration 16 (740) Nature Communications.
Read the full paper here: Half of Land Use Carbon Emissions in Southeast Asia Can be Mitigated through Peat Swamp Forest and Mangrove Conservation and Restoration I Nature Communications.
Enhanced Carbon Removal via Scalable On-Site Pyrolysis and Well-Plugging Systems
Abstract
The United States has extensive biomass resources, with a potential for sustainable production exceeding 1 billion tons annually. The capacity for removal and permanent storage of carbon from the atmospheric carbon cycle is recognized as a key resource for stabilizing global temperatures and maintaining livable conditions by midcentury. Technological pathways that avoid high per-unit capitalization costs hold promise despite broader market uncertainty; building a comparison to the typical economies of scale proposed in the sector, this study investigates a technology development pathway using economies of numbers. This study investigates biomass fast pyrolysis for carbon removal and storage in the U.S.A, evaluating six common feedstocks: corn stover, switchgrass, clean pine, tulip poplar, hybrid poplar, and oriented strand board, supplied through a distributed network. Small-scale biorefineries convert biomass into bio-oil, biochar, and gas at 400–700 °C, with bio-oil transported to centralized storage. Process modeling, techno-economic analysis (TEA), and life-cycle assessment (LCA) reveal a base case (corn stover) bio-oil production of 5.3 tons/day and biochar production of 2.5 tons/day from 10 dry tons/day of feedstock. The base case capital cost is $1.28 million ($128,000/ton/day feedstock capacity; $241,000/ton/day bio-oil capacity), with a minimum bio-oil selling price of $175/ton at a 10 % IRR. The resulting carbon abatement cost is $83.6/ton CO2 (including biochar sequestration) or $152/ton CO2 (excluding it) for the base case. Feedstock production significantly impacts emissions for corn stover (0.20 kg CO2/kg oil) and switchgrass (0.72 kg CO2/kg oil). Switchgrass also has the highest carbon abatement cost, while woody feedstocks are around $100/Mt CO2 (potentially $70/Mt CO2 with a learning factor). Sensitivity analysis identifies feedstock price and production factors as key drivers of the marginal abatement cost (MAC). Small-scale pyrolysis systems are economically advantageous below 6,000 Mt CO2/year, becoming less competitive with direct air capture (DAC) at larger scales. This technology offers significant potential for reducing greenhouse gas emissions by converting diverse biomass resources into bio-oil for long-term storage.
Dubey, P. et al. (2025) Enhanced Carbon Removal via Scalable On-Site Pyrolysis and Well-Plugging Systems 341 (199980) Energy Conversion and Management.
Read the full paper here: Enhanced Carbon Removal via Scalable On-Site Pyrolysis and Well-Plugging Systems I Energy Conversion and Management.