This week’s publication highlights relate to direct air capture, biomass CDR, ocean alkalinity enhancement and enhanced rock weathering.
Clustering Direct Air Capture and Low-Temperature Waste Heat Sources to Optimise the United Kingdom’s Future Energy System
Abstract
Direct Air Carbon Capture and Storage extracts carbon dioxide from atmospheric air and enables long-term sequestration. As an innovative Carbon Dioxide Removal method, Direct Air Capture is essential to achieving net-zero per the 2015 Paris Agreement. However, it is highly energy-intensive compared to alternative carbon removal methods, posing challenges for global decarbonisation and energy demand. Limited energy system integration analysis exists for Direct Air Capture, which is crucial to ensure efficient resource allocation in an already-constrained system. This energy intensive technology requires power, heat, and carbon dioxide storage, and the availabilities of such resources in the transforming energy system are limited. In this study, we analyse energy availability for Direct Air Capture in a low-carbon future energy system. We hypothesise that by clustering Direct Air Carbon Capture and Storage installations with low-temperature waste heat from industrial and nuclear power sources, system losses are reduced, minimising energy demand and operational expenses versus a fully electrified solution. This research bridges the gap between development and implementation of waste heat Direct Air Carbon Capture and Storage by calculating available low-temperature waste heat and applying spatial resource analysis of waste-heat clusters and transport to geological carbon storage sites, based on a United Kingdom case study. The study finds sufficient energy resources to meet Direct Air Capture requirements, even in an energy system less reliant on thermal plants. This approach facilitates a 7–13% cost reduction versus the reference case, with positive cost advantages maintained even under a 60% increase in waste heat input costs.
Middleton, A. et al. (2026) Clustering Direct Air Capture and Low-Temperature Waste Heat Sources to Optimise the United Kingdom’s Future Energy System 347 (120588) Energy Conversion and Management.
Read the full paper here: Clustering Direct Air Capture and Low-Temperature Waste Heat Sources to Optimise the United Kingdom’s Future Energy System I Energy Conversion and Management.
Amine-Appended Hyper-Crosslinked Polymers for Direct Air Capture of CO2
Abstract
Capturing CO2 from the ambient atmosphere is a promising method to reduce the impact of climate change. Fast deployment and scale-up of adsorption-based direct air capture (DAC) technologies are needed to meet the IPCC target and rely, in part, on the development of efficient and scalable low-cost adsorbents. While a benchmark DAC adsorbent, the polymeric resin Lewatit VP OC 1065, has been established, the reasons behind its performance and the potential for further optimization remain largely unknown. Indeed, a fundamental understanding of the relationship between adsorbent pore structure, chemistry, and DAC performance, both equilibrium and kinetics, has yet to be formulated. Here, we have built on the chemistry of Lewatit and synthesized a hyper-crosslinked polymer (HCP) by grafting a microporous chlorine-functionalized support with diethylenetriamine. We produced four different adsorbents by varying the polymerization duration between 10 min and 19 h to assess the impact of pore structure on CO2 uptake at 400 ppm. Reduced degrees of polymerization (i.e., shorter polymerization durations) resulted in higher accessible micropore volume and consequentially increased CO2 uptake and amine efficiency. The best sample achieved an equilibrium uptake of 0.43 mmol/g (400 ppm of CO2, 298 K), which is about half that of the benchmark adsorbent Lewatit VP OC 1065. We have then assessed the CO2 sorption kinetics of this sample (grain size of 24–74 μm) at 400 ppm and 303 K using a gravimetric technique and have compared the results to those of other amine-grafted polymeric adsorbents. We measured a lower bound linear driving force constant (kLDF) of 0.0120 ± 0.0004 s–1. This value is 5.5 times faster than that of the benchmark adsorbent Lewatit VP OC 1065 with the same grain size of 24–74 μm, highlighting the importance of macropore diffusion in addition to the CO2 reaction kinetics. This study shows how synthesis operating conditions alter the pore structures and adsorption behavior of porous polymers and provides the foundation to design better and faster DAC adsorbents.
Sprent, T. et al. (2026) Amine-Appended Hyper-Crosslinked Polymers for Direct Air Capture of CO2. ACS Sustainable Chemistry & Engineering.
Read the full paper here: Amine-Appended Hyper-Crosslinked Polymers for Direct Air Capture of CO2 I ACS Sustainable Chemistry & Engineering.
Life Cycle Assessment of Amending Biomass-Fired Energy Plants with Carbon Capture and Storage
Abstract
This study assesses the environmental performance of amending existing wood biomass-fired combined heat and power (CHP) plants in Northern Europe with carbon capture and storage (CCS). The study quantifies climate change impacts across scenarios involving biomass provision, transportation, energy systems, and CO₂ handling using life cycle assessment. It includes robustness assessment in the form of perturbation analysis and analytical parameter uncertainty.
The default Bioenergy scenario, considering only CHP, results in a net climate burden of 5 kg CO₂-eq/1000 MJ heat produced. In contrast, the default BECCS (Bioenergy with carbon capture and storage) scenario achieves a net climate saving of − 77 kg CO₂-eq/1000 MJ heat. Key influencing factors include biomass provision, transportation, and CO₂ capture efficiency. Further, waste biomass and renewable energy along the value chain significantly reduces emissions. Energy system changes strongly affect the Bioenergy scenario. When the energy system is varied from fossil to renewable, the net climate impact of the Bioenergy scenario shifts from − 19 to + 18 kg CO₂-eq/1000 MJ. On the other hand, the BECCS scenario remains consistently beneficial, with net climate savings between − 81 and − 75 kg CO₂-eq/1000 MJ across all energy systems.
The findings recommend retrofitting existing biomass CHP plants with CCS to achieve robust climate benefits. Recommendations include prioritising waste biomass, avoiding fossil fuels in preparing the biomass, and selecting low-impact transport options to maximise environmental performance.
Varling, A. et al. (2026) Life Cycle Assessment of Amending Biomass-Fired Energy Plants with Carbon Capture and Storage 13 (4) Sustainable Energy Research.
Read the full paper here: Life Cycle Assessment of Amending Biomass-Fired Energy Plants with Carbon Capture and Storage I Sustainable Energy Research.
Enhancing Ocean Alkalinity and CO2 Sequestration via Microalgae-driven Carbonate Precipitation and Biomimetic Catalysis
Abstract
Microalgae-induced carbonate precipitation (MAICP) offers a promising approach for CO2 capture and ocean alkalinity enhancement, but its efficiency in seawater is limited by the slow hydration of CO2, resulting low production of bicarbonate (HCO3−), and reduces algal growth and carbonate (CaCO3) mineralization. In this study, a bio-hybrid biomimetic-MAICP system was developed that integrates the microalga Chlorella vulgaris with carbonic anhydrase-functionalized Zn-based metal–organic framework-5 (CA@fZnMOF-5), encapsulated in alginate beads, to accelerate CO2 hydration and MAICP mineralization. Experiments were conducted under CO2 concentrations of 0.04–15 % and catalyst dosages of 0.5–2.0 g L−1 to evaluate algal growth, CaCO3 precipitation, alkalinity, and total carbon capture. At 5 % CO2, the system produced 1438.48 mg L−1 of biomass, 330.74 mg L−1 of CaCO3, 1978 mg L−1 of alkalinity, and 4941.15 mg L−1 of total carbon capture. CO2 levels above 10 % induced acidification that suppressed mineralization, while optimized catalyst loading helped stabilize pH and support carbonate formation. Increasing the catalyst dosage from 1.0 to 1.5 g L−1 (PBR-2 to PBR-3) yielded only modest improvements, with biomass, CaCO3 precipitation, alkalinity, and total carbon capture increasing by 1.03, 1.08, 1.14, and 1.16 times, respectively. Hence, the CA@fZnMOF-5 beads enhanced CO2 hydration and increased HCO3− availability, promoting photosynthesis and mineral precipitation. Mineral analysis (XRD, FTIR) also confirmed the formation of calcite and aragonite polymorphs. This bio-hybrid approach couples biomimetic catalysis with MAICP and demonstrates a pathway toward scalable ocean-based CO2 sequestration and alkalinity enhancement.
Fazal, T. et al. (2026) Enhancing Ocean Alkalinity and CO2 Sequestration via Microalgae-driven Carbonate Precipitation and Biomimetic Catalysis 398 (124457) Journal of Environmental Management.
Read the full paper here: Enhancing Ocean Alkalinity and CO2 Sequestration via Microalgae-driven Carbonate Precipitation and Biomimetic Catalysis I Journal of Environmental Management.
A Dual Soil Carbon Framework for Enhanced Silicate Rock Weathering: Integrating Organic and Inorganic Carbon Pathways Across Forest and Cropland Systems
Abstract
Enhanced silicate rock weathering (ESRW) has been proposed as a promising carbon dioxide removal strategy, yet its carbon sequestration pathways, durability, and ecosystem dependence remain incompletely understood. Here, we synthesize evidence from field experiments, observational studies, and modeling to compare ESRW-induced carbon dynamics across forest and cropland ecosystems using a unified SOC–SIC dual-pool framework. Across both systems, ESRW operates through shared geochemical processes, including proton consumption during silicate dissolution and base cation release, which promote atmospheric CO2 uptake. However, carbon fate diverges markedly among ecosystems. Forest systems, characterized by high biomass production, deep rooting, and strong hydrological connectivity, primarily favor biologically mediated pathways, enhancing net primary productivity and mineral-associated organic carbon (MAOC) formation, while facilitating downstream export of dissolved inorganic carbon (DIC). In contrast, intensively managed croplands more readily accumulate measurable soil inorganic carbon (SIC) and soil DIC over short to medium timescales, particularly under evapotranspiration-dominated or calcium-rich conditions, although SOC responses are often moderate and variable. Importantly, only a subset of ESRW-driven pathways—such as MAOC formation and secondary carbonate precipitation—represent durable carbon storage on decadal to centennial timescales. By explicitly distinguishing carbon storage from carbon transport, this synthesis clarifies the conditions under which ESRW can contribute to climate change mitigation and highlights the need for ecosystem-specific deployment and monitoring strategies.
Ding, Y. et al. (2026) A Dual Soil Carbon Framework for Enhanced Silicate Rock Weathering: Integrating Organic and Inorganic Carbon Pathways Across Forest and Cropland Systems 17 (1) Forests.
Read the full paper here: A Dual Soil Carbon Framework for Enhanced Silicate Rock Weathering: Integrating Organic and Inorganic Carbon Pathways Across Forest and Cropland Systems I Forests.