This week’s publications focus on three technologies, namely direct air capture, bioenergy with carbon capture and biochar.
A Comprehensive Review of Life Cycle Assessments of Direct Air Capture and Carbon Dioxide Storage
Abstract
This review critically assesses Life Cycle Assessments (LCAs) of Direct Air Capture and Carbon Storage (DACCS) technologies, emphasizing environmental impact and effectiveness of these technologies. As global efforts to mitigate CO₂ emissions intensify, DACCS is increasingly viewed as a promising solution, yet its broader environmental implications require careful consideration. The review synthesizes findings from various LCA studies, revealing substantial variability in life cycle efficiency and environmental impacts across different DACCS systems. Solid sorbent technologies demonstrate average net greenhouse gas reductions of 640 kg CO₂-eq/t CO₂, while liquid sorbent systems achieve reductions of about 560 kg CO₂-eq/t CO₂, with system carbon efficiencies ranging between 56 % and 64 %, influenced by operational conditions and regional factors. Beyond climate impacts, DACCS systems exhibit significant resource demands: water consumption ranges from 1 to 12 tons per ton of CO2 captured, and land use spans 85–4450 km2 based on system configuration and renewable energy requirements. For gigaton-scale facilities, significant environmental trade-offs emerge, including substantial particulate matter emissions (170–180 kt annually) and varying impacts on marine eutrophication (up to 90 % higher for amine-based systems compared to hydroxide-based alternatives). Low-temperature DAC systems exhibit higher human toxicity and ecotoxicity impacts due to increased electricity demands, while metal resource depletion varies significantly based on system design and energy sources. This study highlights the critical need for standardized LCAs and transparent reporting practices to enable consistent comparisons between technologies. Based on the analysis, the review provides recommendations for optimizing system design and deployment strategies to minimize environmental trade-offs while maximizing carbon removal potential. These insights support efforts to achieve carbon neutrality by 2050 in alignment with Intergovernmental Panel on Climate Change (IPCC) targets.
Eke, V. et al. (2025) A Comprehensive Review of Life Cycle Assessments of Direct Air Capture and Carbon Dioxide Storage. Sustainable Production and Consumption.
Read the full paper here: A Comprehensive Review of Life Cycle Assessments of Direct Air Capture and Carbon Dioxide Storage I Sustainable Production and Consumption.
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Efficient and Stable Direct Air Capture with Amine-Functionalized MIL-100(Cr) Metal-Organic Framework
Abstract
Metal–organic frameworks (MOFs) are promising for Direct Air Capture (DAC) due to their tunable pore structures, large surface areas, and chemical functionalization. Amine-functionalized MOFs significantly enhance CO2 adsorption, yet most studies focus on adsorption capacity, with limited research on the impacts of water vapor and oxidative stability in practical DAC applications. Herein, MIL-100(Cr) was modified with polyethyleneimine (PEI), tetraethylenepentamine (TEPA), and diethanolamine (DEA) via impregnation, and their CO2 capture performance under DAC conditions was systematically evaluated, including adsorption capacity, cyclic stability, water resistance, and oxidative stability. PEI-modified MIL-100(Cr) exhibited the best CO2 adsorption capacity, achieving 1.21 mmol g-1 at the same level of amine incorporation and retained over 90% of its initial capacity after 20 cycles. Under humid conditions, the CO2 adsorption performance of solid amine materials was further improved, due to the enhanced utilization of amine sites, particularly increased accessibility of secondary amines. Furthermore, the PEI-modified MIL-100(Cr) exhibited superior oxidative stability compared to TEPA-modified adsorbents. This study provides valuable insights for optimizing MOF-based adsorbents in practical DAC applications.
Sun, M. et al. (2025) Efficient and Stable Direct Air Capture with Amine-Functionalized MIL-100(Cr) Metal-Organic Framework. Environmental Functional Materials.
Read the full paper here: Efficient and Stable Direct Air Capture with Amine-Functionalized MIL-100(Cr) Metal-Organic Framework I Environmental Functional Materials
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Exergy Analysis and Thermodynamic Optimization of a Bioenergy with Carbon Capture and Storage Gas Power Plant Using Monte Carlo Simulation of Sewage Sludge Composition
Abstract
An exergy analysis is performed on the negative CO2 emission gas power plant (nCO2PP), which integrates the fuel preparation, power generation and carbon capture process sections. The cycle is modeled in Aspen Plus coupled with REFPROP, combining deterministic and Monte Carlo stochastic approaches, the latter being a novelty in this work. In all cases studied, the simulations maintain the complex thermodynamic relationships. Exergy losses with areas of potential improvement are identified, while Monte Carlo simulation in Python generates sewage sludge composition, improving cycle realism. In the deterministic approach, the exergies are calculated for a single sewage sludge composition under ambient air conditions with relative humidity of 40 %, 50 % (base case) and 60 % and CO2 air concentration of 375 ppm, 417 ppm (base case) and 1000 ppm, representing a worst case scenario of CO2 increase until the year 2100. For the deterministic base case nCO2PP, the largest exergy losses are observed in the wet combustion chamber (127 kW, 62 % efficiency), gasification process (43 kW, 89 % efficiency), and water condensation in the gas scrubber (43 kW, 87 % efficiency), while the nCO2PP exergy efficiency, related to the chemical exergy of the sewage sludge, is 33.3 %. Sensitivity analysis on turbine vacuum and spray-ejector condenser suction pressure results in an increase of the nCO2PP efficiency by 0.3 % to 33.6 %. Monte Carlo results are incorporated into the Aspen Plus model after the base case optimization. These yield in a range of nCO2PP exergy efficiencies from 33.6 % to 39.7 % with a mean of 37.5 %.
Stasiak, K. et al. (2025) Exergy Analysis and Thermodynamic Optimization of a Bioenergy with Carbon Capture and Storage Gas Power Plant Using Monte Carlo Simulation of Sewage Sludge Composition. 125312 Applied Thermal Engineering.
Read the full paper here: Exergy Analysis and Thermodynamic Optimization of a Bioenergy with Carbon Capture and Storage Gas Power Plant Using Monte Carlo Simulation of Sewage Sludge Composition I Applied Thermal Engineering
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Economic Feasibility of Biochar for Carbon Stock Enhancement in Finnish Agricultural Soils
Abstract
Biochar is a promising climate mitigation measure that can safely capture and store atmospheric carbon dioxide in soil for many years. We conduct an economic analysis to assess the economic feasibility of increasing Finnish mineral agricultural soil carbon stock with biochar in an increasingly dry and warm climate scenario. The Monte Carlo simulations showed that it is challenging to achieve economic feasibility with current carbon prices and biochar costs. To make biochar application economically feasible with a carbon subsidy at the level of the European Union Emissions Trading System (EU ETS) carbon price of 88 EUR/t CO2eq, the cost of biochar material would need to be reduced to less than one-third of its current average price. Alternatively, economic viability could be achieved if the subsidy paid to the farmers was between two to nine times larger than the EU ETS carbon price for the current range of biochar market prices. Lastly, the feasibility can be achieved by simultaneous doubling of the carbon price and halving average biochar cost. Currently, the biochar market is thin and a decrease in biochar cost level is needed to make biochar competitive with other climate change mitigation measures.
Jokubé, M. (2025) Economic Feasibility of Biochar for Carbon Stock Enhancement in Finnish Agricultural Soils. 16 (1) Carbon Management.
Read the full paper here: Economic Feasibility of Biochar for Carbon Stock Enhancement in Finnish Agricultural Soils I Carbon Management.
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Impact of Direct Air Capture Process Flexibility and Response to Ambient Conditions in Net-Zero Transition of the Power Grid
Abstract
Recent studies show that the cost of transitioning the power grid to a net-zero system could be reduced with the integration of direct air capture (DAC) of carbon dioxide as part of the portfolio of technologies. However, existing capacity expansion studies that model DAC assume that it has a constant capture rate, ignoring the ambient environmental conditions that are known to affect the DAC capture rate as well as geographical location. Furthermore, there are currently no studies that endogenously model DAC flexibility, especially the value of load-shifting in such a large-scale industrial process in capacity expansion optimization. This study develops a capacity expansion optimization model that integrates more realistic data on DAC’s response to ambient environmental conditions as well as DAC process flexibility. Results show that ignoring the impact of ambient environmental conditions leads to underestimation of the required cost, DAC capacity and renewable energy capacity to meet the net-zero goal. It is shown that when DAC capture rate data that has been computed as a function of ambient conditions is used, about 22.2%, 2.5% and 1.9% more DAC, wind and solar capacity, respectively, is required to meet net-zero requirements, relative to the often assumed 90% capture rate. Moreover, increasing the operational flexibility of DAC using material storage in silos was found to lower the cost of generation capacity expansion by lowering the DAC and renewable energy capacity needed to meet the net-zero target. These findings will be useful in improving the accuracy of net-zero transition plans that are focused on climate change mitigation.
Arwa, E. and Schell, K. (2025) Impact of Direct Air Capture Process Flexibility and Response to Ambient Conditions in Net-Zero Transition of the Power Grid. 368 (125549) Applied Energy.
Read the full paper here: Impact of Direct Air Capture Process Flexibility and Response to Ambient Conditions in Net-Zero Transition of the Power Grid I Applied Energy.