This week’s publication highlights relate to direct air capture, forestation, biochar and ocean alkalinity enhancement.
Process Systems Engineering: A Key Enabler of Adsorption-Based Direct Air Capture
Abstract
Direct air capture (DAC) is a promising technology for removing carbon dioxide from the atmosphere. However, its widespread deployment is challenged by high energy requirements, water management, sorbent degradation, integration with variable renewable energy sources, and fluctuating climatic conditions. The design, operation, and control of solid adsorption-DAC systems is a complex problem that requires holistic engineering of the adsorbent material, adsorption system, DAC process, and upstream and downstream operations. In this review, we show how Process Systems Engineering (PSE) can address this multiscale system design challenge by highlighting recent PSE advancements in three areas: (i) process-informed sorbent selection, (ii) heat integration and water management, and (iii) technological viability assessments. We summarize the progress that PSE has made in connecting sorbent properties to system design and optimization, outlining the key metrics and workflow needed to advance from sorbent to comprehensive system evaluation. We highlight effective energy and resource management strategies, such as DAC integration with heat and power generation, the use of renewable electricity or underutilized sources from existing infrastructure, and combined heat and water integration. For viability assessments, we emphasize comprehensive approaches that integrate technoeconomic and life cycle assessments with sorbent degradation, geospatial analysis, and scaling predictions. We conclude with future PSE directions that will be important for scaling adsorption-DAC, including process strategies for variable energy and climate conditions, predictive sorbent degradation models, and optimized scheduling to balance energy and capital.
Holmes, H. et al. (2026) Process Systems Engineering: A Key Enabler of Adsorption-Based Direct Air Capture 51 (101202) Current Opinion in Chemical Engineering.
Read the full paper here: Process Systems Engineering: A Key Enabler of Adsorption-Based Direct Air Capture I Current Opinion in Chemical Engineering.
Incorporating Site Suitability and Carbon Sequestration of Tree Species into China’s Climate-Adaptive Forestation
Abstract
Strategic selection and precise matching of climate-resilient tree species are crucial for maximizing the mitigation and adaptation potential of Climate-Smart Forestry. However, current forestation plans often overlook species-specific environmental shifts, leading to suboptimal long-term carbon sequestration. Here we developed a climate-adaptive optimization framework to guide tree species selection and planting in China, based on projected habitat suitability and range shifts under future climate scenarios. Utilizing over 200,000 tree records from China’s National Forest Inventory (1999–2018), we quantified habitat suitability declines of 12.1%–42.9% for currently dominant plantation species by 2060 due to climate change. By optimizing species-site matching and strategically harvesting timber at peak carbon uptake, we identified 43.2 million hectares suitable for climate-resilient forestation between 2025 and 2060, enabling the planting of approximately 46 billion climate-adapted trees with a total sequestration potential of 3822.6 Tg of carbon—a 28.7% increase compared to unmanaged scenarios. Our study highlights the importance of optimizing adaptive forestation strategies to enhance carbon sequestration under future climate conditions, providing technical guidance for climate-resilient forest management in support of China’s net-zero commitment.
Zhang, M. et al. (2025) Incorporating Site Suitability and Carbon Sequestration of Tree Species into China’s Climate-Adaptive Forestation 70 (11) Science Bulletin.
Read the full paper here: Incorporating Site Suitability and Carbon Sequestration of Tree Species into China’s Climate-Adaptive Forestation I Science Bulletin.
Mapping Innovations in Direct Air Capture: A Systematic Patent Review and Literature Comparison
Abstract
Direct air capture (DAC) technologies are gaining increasing attention in both academic and industrial sectors as an essential negative emission technology (NET) in meeting climate change targets. To advance DAC research, this study presents a comprehensive review of DAC technologies from a patent perspective, aiming to understand its current status, future technological trends, and market opportunities. Through two rounds of rigorous screening, 367 patents were finalized and categorized into four sub-technological groups for further analysis: liquid absorption-based DAC, solid adsorption-based DAC, emerging DAC technologies, and DAC integration and application. The temporal trend, geographical distributions, assignee patterns, as well as key technological hotspots within each subgroup, are investigated with comparison with literature. The findings reveal that DAC, once a niche technology, is now strongly driven by commercial interests, with the United States leading in patent filings, followed by China and Europe. Industrial entities dominate the patent landscape, accounting for 72 % of filings. DAC innovations will likely attract growing attention in the coming years, with an expanding diversity of technological approaches.
Wang, J. et al. (2026) Mapping Innovations in Direct Air Capture: A Systematic Patent Review and Literature Comparison 226 (116491) Renewable and Sustainable Energy Reviews.
Read the full paper here: Mapping Innovations in Direct Air Capture: A Systematic Patent Review and Literature Comparison I Renewable and Sustainable Energy Reviews.
Do Oversimplified Durability Metrics Undervalue Biochar Carbon Dioxide Removal?
Abstract
Soil amendment of biochar—the solid product of biomass pyrolysis—is one of few engineered strategies capable of delivering carbon dioxide removal (CDR) today. Quantifying CDR for biochar projects hinges critically on the durability of biochar materials once amended in soil. However, consensus on the definition of durability is still evolving, and as a result, standards developing organizations have generated a variety of different methodologies to assess the removal value of biochar projects. These methodologies primarily rely on single-parameter regression models to link the molar H/C ratio—an easily measurable bulk chemical metric—to the modeled durability of biochar materials. Specific deployment variables are not commonly considered. Thus, although H/C-based methodologies simplify project development and CDR assessment, questions remain as to how well they predict real project outcomes. Via a re-analysis of existing biochar incubation data and several case studies, we show that durability standards based on bulk compositional metrics are biased towards particular feedstocks and may not account for key environmental drivers. Without provisions for these factors, we find that existing assessment models appear to discount the removal value of biochar projects significantly. However, our conclusions rely on predictive models with important weaknesses and unknown uncertainty—pointing to a need to develop a use-aligned database. Limitations notwithstanding, our findings ultimately suggest the biochar ‘durability problem’ may be an artifact of the desire to simplistically define it. To reliably credit CDR, we propose a series of recommendations, including the creation of representative distributions for current feedstocks and environmental gradients to better align experimental data with real-world practices. Further, we suggest an approach to integrate in-field measurement protocols with existing strategies to evaluate CDR value, with potential to co-generate data to guide deployment, maximize agronomic co-benefits, and improve confidence in project integrity.
Ringsby, A. and Maher, K. (2025) Do Oversimplified Durability Metrics Undervalue Biochar Carbon Dioxide Removal? 20 (034001) Environmental Research Letters.
Read the full paper here: Do Oversimplified Durability Metrics Undervalue Biochar Carbon Dioxide Removal? I Environmental Research Letters.
Maximizing the Detectability of Ocean Alkalinity Enhancement (OAE) While Minimizing Its Exposure Risks: Insights from a Numerical Study
Abstract
Ocean alkalinity enhancement (OAE) can potentially remove gigatons of CO2 from the atmosphere for durable storage in the ocean. Before implementing OAE at climate-relevant scales, questions about its safety and verifiability must be addressed. Operational deployment poses a dilemma between pursuing large detectability, essential for effective monitoring, reporting, and verification, and ensuring environmental safety and satisfying regulatory requirements. In this study, we present a computationally efficient approach, based on a high-resolution, coupled circulation-dissolution model of Halifax Harbor, to simulating the addition, transportation, dissolution, and sinking of various theoretical alkaline feedstocks for different dosages, seasons, and addition sites. Detectability and exposure risk of OAE are quantified and an approach for optimizing OAE deployment is demonstrated. Mean residence times (MRT) are calculated for different subregions and seasons. Results show that for a given amount of feedstock, summer is more favorable from the perspective of detectability but also creates higher exposure risks than other seasons because of a longer MRT. The exposure risk can be mitigated while maintaining large detectability by choosing optimal feedstocks with different characteristics for different seasons. The exposure risk can also be reduced by spreading alkalinity over multiple addition sites. The optimum allocation, where the largest detectability is sought without violating regulatory requirements, is specific to each season, dosage, and choice of feedstock. OAE deployments should be tailored taking into account local hydrography, season, dosage, and feedstock characteristics. Our approach provides a practical avenue for optimizing deployments.
Wang, B. et al. (2025) Maximizing the Detectability of Ocean Alkalinity Enhancement (OAE) While Minimizing Its Exposure Risks: Insights from a Numerical Study 13 (4) Earth’s Future.
Read the full paper here: Maximizing the Detectability of Ocean Alkalinity Enhancement (OAE) While Minimizing Its Exposure Risks: Insights from a Numerical Study I Earth’s Future.