This week’s publication highlights cover a wide range of issues related to carbon capture and storage, grey carbon, carbon removal efficiency and energy requirements, bioenergy with carbon capture and storage as well as inorganic and organic carbon removal.
Carbon Capture and Storage via Enhanced Carbonate Weathering Coupled with Aquatic Photosynthesis: Potential, Cost, and Advantages
Abstract
The application of crushed rock powders to terrestrial or marine ecosystems (termed enhanced rock weathering, ERW) is regarded as an effective carbon dioxide removal (CDR) mechanism for mitigating ongoing climate change. As a potential ERW material, carbonate is characterized by rapid dissolution kinetics and is environmentally friendly. However, the CDR potential, cost, and effectiveness of carbonate-based ERW implementation are not well explored. Using a carbonate equilibrium equation, and the CMIP6 (Coupled Model Intercomparison Project Phase 6) GCM (Global Climate Model) and LCA (Life Cycle Assessment) models, here we analyze the CDR potential, carbon footprint, and cost of a carbonate-based RW strategy (so-called enhanced carbonate weathering, ECW). We estimated that the current global potential carbon removal (PCR) of ECW could reach ~2.66 (Representative Concentration Pathway (RCP) 4.5) and ~ 2.82 (RCP8.5) Gt CO2 a−1, and that the cumulative CO2 removal by the end of this century could reach 241.32 Gt CO2 a−1 (RCP4.5) and 246.64 Gt CO2 a−1 (RCP8.5). This could potentially neutralize ~23.11 % (RCP4.5) and ~ 23.62 % (RCP8.5) of future global carbon dioxide emissions. We also found that the global CDR potential of ECW can respond sensitively to global environmental perturbations, and that the CDR potential in the future will generally increase in high-latitude regions due to global climate change. We compared the cost of enhanced silicate weathering (ESW) with ECW implementations for seven major countries with high CDR potential and found that the cost per mol of CO2 removal by ECW is 1.33–2.07 times lower than that for ESW. While the stability of dissolved inorganic carbon (DIC) is debated in many studies, we suggest that the new approach represented by ECW should consider the role of aquatic photosynthesis. Overall, the biological pump induced by aquatic photosynthesis is significant for increasing the carbon storage of ECW in inland waters. For future ERW implementation, we stress the need to develop an Enhanced Coupled Carbonate Weathering plus aquatic photosynthesis strategy (ECCW) that can both offset the negative effect of CO2 degassing and also increase the total CDR of ECW to a greater degree than expected. ECCW remains in the developmental stage, and its large-scale implementation requires further laboratory and field experiments to determine its CDR-efficiency and environmental effects and risks.
Shi, L. et al. (2025) Carbon Capture and Storage via Enhanced Carbonate Weathering Coupled with Aquatic Photosynthesis: Potential, Cost, and Advantages. 105149 Earth-Science Reviews.
Read the article here: Carbon Capture and Storage via Enhanced Carbonate Weathering Coupled with Aquatic Photosynthesis: Potential, Cost, and Advantages I Earth-Science Reviews.
Grey Carbon - A New Nature-Positive Carbon Removal Technology for the Built World
Abstract
Humanity is in a race to reduce carbon dioxide levels in the atmosphere. Emissions must be reduced while also accelerating net carbon dioxide removal (CDR). Historically, carbon removal has been shouldered by “green” and “blue” nature—land, coastal areas, and ocean. With the world’s growing population, impacts from climate change, and increasing urbanization, it is clear nature cannot handle all the CDR needed. Natural systems are under threat, risking their ability to maintain the same rate of carbon sequestration. Man-made technology must deliver more. The IPCC Assessment Report 6 (AR6) highlights a mix of nature- and technology-based CDR solutions that will be needed. Here, we look at a new CDR solution for the construction industry, which is responsible for 38% of global CO2 emissions. Since climate change is only increasing demand for construction, we must reimagine how and what we build with. We need building technologies that can help keep their own industry’s emissions in check while also reducing CO2 from the atmosphere. This is where “grey carbon” comes in. Like its blue and green cousins, grey carbon offers net carbon removal from man-made technology and presents a pathway that delinks pollution and development. Here, we use a case example of how the Bahamas is turning to a grey carbon building product to respond to housing demand and climate adaptation. We describe the science behind this CDR technology and apply financial valuation techniques to calculate the monetary value that could be derived from the grey carbon credits. We show how grey carbon delivers climate, nature, and community benefits from the following: CO2 avoidance and removal during production, longer-term carbon removal as the materials continue to weather, ocean protection through reduced brine waste, and social benefits from the sale of grey carbon credits. We show that a 1250 ft2 home built with this cement can deliver 170.94 tCO2e credits over 20 years for a present value of $38,145 per home and $57.22 million for 1500 homes. We conclude that grey carbon can mitigate emissions from the built world while also helping to deliver a future in which the biosphere and Technosphere, blue, green, and grey climate solutions, coexist as allies for human well-being and climate stabilization.
Chami, R. et al. (2024) Grey Carbon - A New Nature-Positive Carbon Removal Technology for the Built World Springer Nature 235-254.
Read the full paper here: Grey Carbon - A New Nature-Positive Carbon Removal Technology for the Built World I Springer Nature
Carbon Removal Efficiency and Energy Requirement of Engineered Carbon Removal Technologies
Abstract
To ensure carbon negativity, processes that achieve carbon dioxide removal (CDR) from the atmosphere must consider lifecycle emissions and energy requirements across the entire system. We conduct a harmonized lifecycle greenhouse gas assessment to compare the carbon removal efficiency and total energy required for twelve engineered carbon removal technologies. The goal of this comparison is to enable the assessment of diverse engineered carbon removal approaches on a consistent basis. Biomass-based CDR approaches generally maintain higher carbon removal efficiency than direct air capture (DAC) and, to a lesser extent, enhanced rock weathering (ERW) due to the high concentration of carbon within the biomass and the relatively low energy requirements for processing the biomass for removal. Nevertheless, there is high variance in CDR approaches, as some biomass conversion processes (e.g., pyrolysis for biochar or gasification for fuels) exhibit high, yet variable, carbon losses, while DAC and ERW can utilize low-carbon energy inputs for more efficient removal. Regarding energy use, ERW and biomass-based approaches generally require less energy than DAC today, but biomass approaches again exhibit more variation. Displacement of products, when included, increases the total climate benefits of biomass used for bioenergy with carbon capture and storage (BECCS) and biochar. These two measures are intuitive metrics to guide allocation of scarce resources amongst potentially competing uses of biomass and low-carbon energy.
Sanchez, D. et al. (2025) Carbon Removal Efficiency and Energy Requirement of Engineered Carbon Removal Technologies.3 RSC Sustainability.
Read the full paper here: Carbon Removal Efficiency and Energy Requirement of Engineered Carbon Removal Technologies I RSC Sustainability.
CO2 Storage Infrastructure and Cost Estimation for Bioenergy with Carbon Capture and Storage in Northern Thailand
Abstract
Bioenergy with carbon capture and storage (BECCS) is a promising technology for achieving net-zero emissions by integrating renewable energy production with CO₂ sequestration. The current study evaluated CO₂ storage infrastructure in Northern Thailand’s onshore saline formations to support BECCS deployment and contribute to the nation’s decarbonization goals under its Nationally Determined Contribution. The geological storage potential, CO₂ plume migration, storage containment, and cost estimates of the Lampang and Nong Bua Basins were comprehensively assessed. Numerical simulations were performed to evaluate storage capacities and containment mechanisms, incorporating reservoir heterogeneity and geomechanical constraints. Results indicated a combined dynamic storage capacity of 29 Mtpa, with the BECCS cluster designed to store 10 Mtpa: 4 Mtpa allocated to the Nong Bua Basin and 6 Mtpa to the Lampang Basin. The Lampang Basin also offered excess capacity to accommodate 15 Mtpa from the coal-fired power plant located in Lampang. Stratigraphic heterogeneity of reservoir was found to enhance storage containment through improved residual and solubility trapping, although mineral trapping remained negligible. The levelized cost of CO₂ storage was estimated at 7.99 USD/tonne for a 35-year injection period and 8.23 USD/tonne for a 25-year injection period, with operational costs accounting for more than half of the total cost. These estimates align with global benchmarks, validating the methodology while reflecting Thailand-specific conditions. The current work highlights the feasibility of BECCS deployment in Thailand, presenting a scalable and cost-effective solution for CO₂ sequestration. The findings also offer a robust framework for integrating geomechanics, reservoir heterogeneity, and cost modeling in CCS design, with broader implications for regions pursuing similar decarbonization goals worldwide.
Tangparitkul, S. et al. (2025) CO2 Storage Infrastructure and Cost Estimation for Bioenergy with Carbon Capture and Storage in Northern Thailand. Carbon Capture Science & Technology 15 (100425) Carbon Capture Science & Technology.
Read the full paper here: CO2 Storage Infrastructure and Cost Estimation for Bioenergy with Carbon Capture and Storage in Northern Thailand I Carbon Capture Science & Technology
Drivers of Inorganic and Organic Carbon Removal in Aged Oceanic Crust
Abstract
Large volumes of fluid flow through aged oceanic crust. Given the scale of this water flux, the exchange of organic and inorganic carbon that it mediates between the crust and deep ocean can be significant. However, off-axis carbon fluxes in older oceanic crust are still poorly constrained because access to low-temperature fluids from this environment is limited. At North Pond, a sedimented depression located on 8-million-year-old crust on the flank of the Mid-Atlantic Ridge, circulating crustal fluids are accessible through drilled borehole observatories. Here, fluids are cool (≤ 20 °C), oxygenated and bear strong geochemical similarities to bottom seawater. In this study, we report the concentrations and isotopic composition of dissolved organic and inorganic carbon from crustal fluids that were sampled six years after the installation of borehole observatories. These better represent the fluid geochemistry prior to drilling and perturbation than earlier studies. Radiocarbon-based signatures within carbon reservoirs support divergent shallow and deep fluid pathways within the crust. We also report a net loss of both dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) from the fluid during isolation in the crust. The removal of DOC is isotopically selective and consistent with microbe-mediated DOC oxidation. The loss of DIC is consistent with carbonate precipitation, although geochemical signatures of DIC addition to the fluids from DOC oxidation and basalt weathering are also evident. Extrapolated to global fluxes, systems like North Pond could be responsible for a net loss of ∼ 1011 mol C yr−1 of DIC and ∼ 1011 mol C yr−1 of DOC during the circulation of fluids through oceanic crust at low temperatures.
Walter, S. et al. (2025) Drivers of Inorganic and Organic Carbon Removal in Aged Oceanic Crust. 394 Geochimica et Cosmochimica Acta
Read the full paper here: Drivers of Inorganic and Organic Carbon Removal in Aged Oceanic Crust I Geochimica et Cosmochimica Acta.