This week’s selected publications cover a wide range of issues related to carbon removal in agricultural farms, the deployment of carbon capture technologies in certain manufacturing industries, direct air capture, carbon mineralization and ambiguities surrounding the utilization of biochar for removing carbon dioxide.
Carbon Removal Potentials in Agricultural Systems - Participatory Scenario Modelling with Farmers in Sweden
Abstract
Estimates of theoretical climate change mitigation potentials in agriculture need to be complemented with investigations of factors that influence deployment. This study introduces a framework for landscape-level assessment of climate change mitigation in agriculture that accounts for existing land uses, soil carbon stocks, and farmers’ preferences concerning specific mitigation options. The framework is used in an assessment of the deployment potentials for selected mitigation options in an agricultural landscape in Sweden, in which arable land covers approximately one-third of the land area. Three options were found to be preferable by farmers: biochar as soil amendment, cover crops, and (an increased) cultivation of ley crops in crop rotations. Cultivation of cover crops and leys was found to increase SOC stocks by 1.9 and 1.6 MgC ha−1 over three decades, respectively. About 10.2 MgC ha−1 is sequestered in soils over three decades when biochar is added as a soil amendment, if 50% of available residues are collected and utilized. This can be compared with GHG emissions from agriculture from the studied area, estimated at 1.6 Mg CO2-eq ha−1 yr−1 (GWP100). The framework was found useful for assessing mitigation options in the agriculture sector, underlining farmer involvement to identify actionable strategies.
Rehn, A., Berndes, G., Cederberg, C. & Englund, O. (2024) Carbon Removal Potentials in Agricultural Systems - Participatory Scenario Modelling with Farmers in Sweden. Carbon Management 15 (1).
Read the full paper here: Carbon Removal Potentials in Agricultural Systems - Participatory Scenario Modelling with Farmers in Sweden I Carbon Management
Multi-criteria Evaluation of Carbon Capture Technologies in Steel, Cement, Petrochemical and Fertilizer Industries: Insights for Emerging and Developed Countries
Abstract
This research addresses the global imperative to tackle climate change by evaluating different carbon capture technologies based on various criteria in hard-to-electrify sectors such as steel, cement, petrochemicals, and fertilizers, providing practical insights for policymakers engaged in the shift toward low-carbon industrial processes. The study employs a Multi-Criteria Decision-Making (MCDM) approach, specifically the Analytical Hierarchy Process (AHP), using a systematic and objective evaluation process, integrating rigorous pairwise comparisons using the Saaty scale through logical reasoning, along with eigenvalue calculations, resulting in a criteria and strategy ranking. In evaluating carbon capture technologies for heavy industry, external support (regulatory adherence, global collaboration, and financial incentives) is crucial for technology evaluation, which carries the highest weight (21.3 %). Technology maturity and reliability follow closely (17.4 %), emphasizing the importance of proven track records. Carbon capture efficiency and environmental and health impacts share a relatively high weight (13.7 %). Scalability and integration with existing infrastructure carry moderate weights (7.8 %). Energy requirements are less critical (6.7 %), while the cost-effectiveness criterion has a relatively low weight (3.9 %). Duration of operation and public acceptance and social impact also carry low weights (3.9 %), creating a balanced evaluation considering both technical and socio-economic factors. Post-combustion capture excels with a high score, making it suitable for emission reduction in hard-to-abate industries. Pre-combustion capture and oxy-fuel combustion have moderate scores, indicating balanced performance. Direct Air Capture faces challenges, resulting in a lower score, while carbon mineralization and biomass co-firing with carbon capture receive the lowest scores, suggesting potential limitations. We discuss the impact of climate change on carbon capture technologies, the influence of critical materials, the practical implications for Moroccan industries such as Lafarge Holcim (cement), OCP (phosphate mining and petrochemical processing), and Sonasid (steel), as well as for emerging and industrialized economies, including hydrogen, ammonia, and kerosene production from fossil fuels.
Bouramdane, A. (2024) Multi-criteria Evaluation of Carbon Capture Technologies in Steel, Cement, Petrochemical and Fertilizer Industries: Insights for Emerging and Developed Countries. Science of the Total Environment 957 (177754)
Read the full paper here: Multi-criteria Evaluation of Carbon Capture Technologies in Steel, Cement, Petrochemical and Fertilizer Industries: Insights for Emerging and Developed Countries I Science of the Total Environment
Development of Amino-Functionalized Silica by Co-condensation and Alkylation for Direct Air Capture
Abstract
CO2 chemisorption using amine-based sorbents is one of the most effective techniques for carbon capture and storage. Solid CO2 sorbents with amines immobilized on their surface have been attracting attention due to the easy collection of sorbents and reusability. In this study, we developed a solid CO2 adsorbent by co-condensation of a silanizing reagent having a chloroalkyl group and tetraethyl ethoxysilane, followed by alkylation of the chloroalkyl group with diamine. The fabricated amine-immobilized silica with a high density of amino groups on its surface achieved the chemical adsorption of 400 ppm of CO2 with 4.3 wtCO2 % loading, CO2 release upon heating at 80 °C, and reusability for adsorption and desorption cycles with high amine utilization efficiency (0.20 molCO2/mol–N). This surface modification method is applicable to various amines bearing more than two amino functional groups, enabling the development of solid CO2 sorbents for the selective capture of low-concentration CO2 directly from the air.
Kikkawa, S., Kataoka, M. & Yamazoe, S. (2024) Development of Amino-Functionalized Silica by Co-condensation and Alkylation for Direct Air Capture ACS Omega
Read the full paper here: Development of Amino-Functionalized Silica by Co-condensation and Alkylation for Direct Air Capture I ACS Omega
Non-symbiotic N2 Fixation is Less Sensitive to Changes in Temperature than Carbon Mineralization in Northern Forest Soils
Abstract
Northern forests are characterized by low temperatures that play a key role in the whole ecosystem functioning. However, Northern forests are expected to experience the largest temperature increase of all forest biomes in the next decades, which could affect central ecosystem processes, such as carbon (C) mineralization and N2 fixation. Aiming to clarify the temperature-dependence of non-symbiotic N2 fixation and C mineralization in Northern forest soils, we quantified the rates of both processes in soils of Scots Pine (Pinus sylvestris) forests located along a temperature gradient in Sweden in laboratory incubations at different temperatures (5, 12 and 20 °C). Our results show that N2 fixation by free-living bacteria in the organic layer of these forest soils ranges between 2 and 10 kg N ha−1 yr−1 which highlights the importance of non-symbiotic N2 fixation in Northern forest soils. We found a positive correlation between non-symbiotic N2 fixation per area and mean annual temperature (MAT). This relationship was caused by the positive relationship between the organic layer stock and MAT rather than by the direct effect of temperature on the process rate. In contrast, C mineralization per g of soil was negatively related to MAT. Furthermore, our results show that C mineralization is more sensitive to changes in incubation temperature (it increased by a factor of 2.2 from 5 to 12 °C as well as from 12 to 20 °C) than non-symbiotic N2 fixation that was not significantly affected by incubation temperature. Taken together, while N2 fixation responded little to changes in incubation temperature, our results suggest that the higher N2 fixation rate per area at sites with higher MAT is beneficial for primary production and organic matter inputs to soil leading to larger organic layer stocks. Hence, there is a positive, temperature-dependent feedback among non-symbiotic N2 fixation, primary production, and the organic layer formation in Northern forests.
Vazquez, E. & Spohn, M. (2025) Non-symbiotic N2 Fixation is Less Sensitive to Changes in Temperature than Carbon Mineralization in Northern Forest Soils. Geoderma 453 (117128).
Read the full paper here: Non-symbiotic N2 Fixation is Less Sensitive to Changes in Temperature than Carbon Mineralization in Northern Forest Soils I Geoderma
Uncertainty in Determining Carbon Dioxide Removal Potential of Biochar
Abstract
A quantitative and systematic assessment of uncertainty in life-cycle assessment is critical to informing sustainable development of carbon dioxide removal (CDR) technologies. Biochar is the most commonly sold form of CDR to date, and it can be used in applications ranging from concrete to agricultural soil amendments. Previous analyses of biochar rely on modeled or estimated life-cycle data and suggest a cradle-to-gate range of 0.20–1.3 kg CO2 net removal per kg of biomass feedstock, driven by differences in energy consumption, pyrolysis temperature, and feedstock sourcing. Herein, we quantify the distribution of CDR possible for biochar production with a compositional life-cycle inventory model paired with scenario-aware Monte Carlo simulation in a “best practice” (incorporating lower transportation distances, high pyrolysis temperatures, high energy efficiency, recapture of energy for drying and pyrolysis energy requirements, and co-generation of heat and electricity) and “poor practice” (higher transportation distances, lower pyrolysis temperatures, low energy efficiency, natural gas for energy requirements, and no energy recovery) scenarios. In the best-practice scenario, cradle-to-gate CDR (which is representative of the upper limit of removal across the entire life cycle) is highly certain, with a median removal of 1.4 kg of CO2e / kg biomass and results in net removal across the entire distribution. In contrast, the poor-practice scenario results in median net emissions of 0.090 kg CO2e / kg biomass. Whether this scenario emits (66% likelihood) or removes (34% likelihood) carbon dioxide is highly uncertain. The emission intensity of energy inputs to the pyrolysis process and whether the bio-oil co-product is used as a chemical feedstock or combusted are critical factors impacting the net carbon dioxide emissions of biochar production, together responsible for 98% of the difference between the best- and poor-practice scenarios.
Kane, S., Thaneya, A., Gursel, A., Fan, J., Bose, B., Hendrickson, T., Nordahl, S., Scown, C., Miller, S. & Horvath, A. (2024) Uncertainty in Determining Carbon Dioxide Removal Potential of Biochar. Environmental Research Letters.
Read the full paper here: Uncertainty in Determining Carbon Dioxide Removal Potential of Biochar I Environmental Research Letters