Search Results (22)

The rise in greenhouse gases underscores the urgency of carbon dioxide removal (CDR) as a complement to emission reductions. Enhanced rock weathering (ERW) holds promise by coupling geochemical carbon sequestration with agronomic benefits, although integrative experimental evidence remains limited. This study evaluated two amendments (recycled concrete in wheat, C₃, and basalt in maize, C₄) under ambient and elevated CO₂ conditions (~1000 ppm). Conducted in a greenhouse over 21 weeks using loam soils, the experiment evaluated four treatments comprising three different particle-size ranges (<2 mm, 2–6 mm, and 6–15 mm) and a control. Plant growth (height, total and partitioned biomass), grain quality (N and protein), and soil properties (pH, electrical conductivity, and carbonates) were measured. Elevated CO₂ enhanced biomass, particularly vegetative biomass in wheat (+42.6%) and root biomass in maize (+55%), without significantly increasing yield. In wheat, particle size was decisive: intermediate fractions (2–6 mm) yielded the best results. In maize, basalt effects were less consistent. Concrete amendments increased soil pH and carbonate content, especially with coarse particles and elevated CO₂, whereas basalt-induced responses were slower and more variable. These findings confirm the potential of ERW as a dual climate–agronomic strategy while highlighting the need for long-term, field-scale validation. Full article

Supply chains are a primary contributor to global greenhouse gas (GHG) emissions, rendering their decarbonization an essential dimension of sustainable development. Artificial intelligence (AI) provides a transformative pathway by facilitating proactive emission avoidance through operational efficiency, transparency, and resilience, in contrast to post-emission mitigation approaches such as carbon capture. This study explores the potential of AI to support indirect carbon dioxide removal (CDR) via supply chain decarbonization, adopting a comparative case study methodology. Empirical evidence is drawn from Tunisian agri-food, textile, and port logistics sectors, based on multi-source datasets spanning 6–12 months and covering fleet sizes ranging from 40 to 250,000 units. Methodological robustness was ensured through the use of pre-intervention baselines, statistical imputation for missing data (<5%), and validation against 20% out-of-sample test sets. Results indicate that AI-enabled interventions achieved annual avoided emissions between 500 and 1500 tCO₂ and reduced fuel consumption by 12–15%, with sensitivity analyses incorporating ±8–12% error margins. Among the approaches tested, hybrid models integrating operational and strategic layers demonstrated the most pronounced impact, aligning immediate efficiency gains with long-term systemic decarbonization. Furthermore, AI facilitates renewable energy integration, digital twin applications, and compliance with international sustainability frameworks, notably the Paris Agreement and the United Nations Sustainable Development Goals. Nevertheless, challenges related to data quality, computational demands, limited expertise, and organizational resistance constrain scalability. The findings underscore AI’s dual role as a technological enabler and systemic driver of supply chain decarbonization, advancing its positioning within global environmental sustainability transitions. Full article

Enhanced Rock Weathering (ERW) is a promising carbon dioxide removal (CDR) strategy that accelerates mineral dissolution, sequestering atmospheric CO₂ while improving soil health. This study builds on prior applications of soil calcimetry by investigating its ability to resolve short-term carbonate fluxes and rainfall-modulated weathering dynamics in wollastonite-amended croplands. Conducted over a single growing season (May–October 2024) in temperate row-crop fields near Port Colborne, Ontario—characterized by fibric mesisol soils (Histosols, FAO-WRB)—this study tests whether calcimetry can distinguish between dissolution and precipitation phases and serve as a proxy for weathering flux within the upper soil horizon, under the assumption that rapid pedogenic carbonate cycling dominates alkalinity retention in this soil–mineral system. Monthly measurements of soil pH (Milli-Q and CaCl₂) and calcium carbonate equivalent (CCE) were conducted across 10 plots, totaling 180 composite samples. Results show significant alkalinization (p < 0.001), with average pH increases of ~+1.0 unit in both Milli-Q and CaCl₂ extracts over the timeline. In contrast, CCE values showed high spatiotemporal variability (−2.5 to +6.4%) without consistent seasonal trends. The calcimetry-derived weathering proxy, log (Σ ΔCCE/Δt), correlated positively with pH (r = 0.652), capturing net carbonate accumulation, while the kinetic dissolution rate model correlated strongly and negatively with pH (r ≈ −1), reflecting acid-promoted dissolution. This divergence confirms that the two metrics capture complementary stages of the weathering–precipitation continuum. Rainfall strongly modulated short-term carbonate formation, with cumulative precipitation over the previous 7–10 days enhancing formation rates up to a saturation point (~30 mm), beyond which additional rainfall yielded diminishing returns. In contrast, dissolution fluxes remained largely independent of rainfall. These results highlight calcimetry as a direct, scalable, and dynamic tool not only for monitoring solid-phase carbonate formation, but also for inferring carbonate migration and dissolution dynamics. In systems dominated by rapid pedogenic carbonate cycling, this approach captures the majority of alkalinity fluxes, offering a conservative yet comprehensive proxy for CO₂ sequestration. Full article

The decarbonization of hard-to-defossilize sectors, such as international maritime transport, requires innovative, and at times disruptive, energy solutions that combine efficiency, scalability, and climate benefits. Therefore, power-to-liquid (PtL) routes have stood out for their potential to use low-emission electricity for the production of synthetic fuels, via electrolytic hydrogen and CO₂ capture. However, the high energy demand inherent to these routes poses significant challenges to large-scale implementation. Moreover, PtL routes are usually at most neutral in terms of CO₂ emissions. This study evaluates, from a thermo-energetic perspective, the optimization potential of an e-methanol synthesis route through integration with a biomass oxy-fuel combustion process, making use of electrolytic oxygen as the oxidizing agent and the captured CO₂ as the carbon source. From the standpoint of a first-law thermodynamic analysis, mass and energy balances were developed considering the full oxygen supply for oxy-fuel combustion to be met through alkaline electrolysis, thus eliminating the energy penalty associated with conventional oxygen production via air separation units. The balance closure was based on a small-scale plant with a capacity of around 100 kta of methanol. In this integrated configuration, additional CO₂ surpluses beyond methanol synthesis demand can be directed to geological storage, which, when combined with bioenergy with carbon capture and storage (BECCS) strategies, may lead to net negative CO₂ emissions. The results demonstrate that electrolytic oxygen valorization is a promising pathway to enhance the efficiency and climate performance of PtL processes. Full article

Direct air capture (DAC) has recently gained interest as a carbon dioxide removal (CDR) method to reduce atmospheric CO₂. DAC is mainly studied through standalone separation technologies, especially adsorption and absorption. Hybrid DAC, combining separation technologies, is rarely investigated and is the main topic of this work. This study investigates hybrid DAC using adsorption for pre-concentration up to a few percent or tens of percent depending on the case studied and membrane separation to concentrate the CO₂ stream to high purity (>90%). Adsorption regeneration by temperature swing adsorption (TSA) and vacuum thermal swing adsorption (VTSA) are compared, and VTSA regeneration achieved higher pre-concentration outlet CO₂ purity (15–30%) than TSA regeneration (1–10%). Membrane separation is studied depending on inlet CO₂ purity and outlet-required purity (90 or 95%), which influence the energy requirement and cost of capture. For all cases studied, the cost of capture remained high (>1700 €/tCO₂) with a high energy requirement (>2 MWh_e/tCO₂ and >27 GJ/tCO₂). The adsorption pre-concentration step accounted for the majority (>80%) of the energy requirement and cost of capture, and future work should be focused on preferentially improving adsorption step performance. Full article

In alignment with Saudi Arabia’s Vision 2030, the Kingdom aims to achieve one of its main environmental targets: reaching net zero emissions by 2060. This ambitious goal can be realized through Carbon Dioxide Removal (CDR) technologies, particularly Direct Air Capture (DAC), which is among the most promising solutions. DAC offers high potential for extracting Carbon Dioxide (CO₂) directly from the atmosphere and is considered sustainable, especially when powered by renewable energy rather than fossil fuels. However, the technology remains highly cost-intensive. This paper presents a techno-economic assessment of renewable energy configurations to determine the most cost-effective solutions for DAC deployment. The evaluation focuses on Net Present Cost (NPC) and Levelized Cost of Energy (LCOE) across several regions in Saudi Arabia, using the Hybrid Optimization of Multiple Energy Resources (HOMER) Pro software (version 3.18.4). Full article

India’s revised nationally determined contribution at COP26 set a net-zero target for 2070, but the role of carbon dioxide removal (CDR) in achieving this goal remains unclear. This study quantifies the contribution of land-based CDR—bioenergy carbon capture and storage, biochar, and afforestation—in achieving India’s net-zero goal. Additionally, a stylised scenario explores an accelerated net-zero target by 2050 in India`s climate target. The global emission target is modelled to follow India’s climate ambition in both stylised scenarios. The results show that the ambitious 2050 net-zero pathway requires 56 GtCO₂ of cumulative novel CDR across the century, compared to 47 GtCO₂ under the 2070 scenario, with both requiring around 1 GtCO₂/year at net-zero. A higher ambitious pathway leads to increased economic costs, with a mid-century carbon price of USD 938, compared to USD 174 in the 2070 scenario. Without novel CDR methods, the cost of achieving net zero by 2050 quadruple. The accelerated 2050 net-zero pathway also intensifies land and water trade-offs, reducing land for crop production while increasing water demand for electricity and biomass. Despite these challenges, it limits end-of-century warming to 1.46 °C, compared to 1.79 °C under the 2070 scenario. These findings highlight the importance of clearly defined climate targets, scalable CDR strategies, and integrated resource management to balance climate ambition with sustainable development. Full article

Efforts to address anthropogenic climate change have been focused sensibly on mitigation and adaptation. However, given the difficulties in the implementation of a rapid global mitigation process, increasing attention is being given to geoengineering as a way to countervail some of the climate change impacts. This development has increased the private investment in geoengineering research in the last few years, leading to patent filing. The article examines the recent evolution of patents in the emerging field of geoengineering technologies. Despite the secrecy surrounding the field of geoengineering, especially solar radiation management at the state level, patent databases provide transparency, offering technical details, market insights, and information about the key players. Patents, published 18 months after filing, reveal valuable data about geoengineering technologies, the targeted markets, and involved stakeholders. The databases of the International Patent Classification (IPC) and Cooperative Patent Classification (CPC) are used. The focus of the present analysis is on patents in the sub-domains of carbon dioxide removal and solar radiation management and on those held by the large oil producer corporations. The results highlight the patents filed in the controversial area of SRM. The growing economic significance of geoengineering requires the protection of innovations through patents coupled with the implementation of a global governance system based on climate justice and ethical responsibility. Full article

Various Higher Education Institutions (HEIs) set themselves goals to become carbon neutral through the implementation of different reduction strategies such as the replacement of fossil-fueled vehicles with electric cars. However, even if all reduction measures are taken, residual GHG emissions will still remain. Therefore, most HEIs have to compensate for the remaining emissions by, for example, buying carbon credits. However, due to growing criticism of carbon credit purchases, HEIs need to explore options for establishing carbon sinks on their own premises to offset their remaining, unavoidable emissions. This study aimed to assess the CO₂ footprint of Hochschule Geisenheim University (HGU) as an exemplary HEI, identify emission hot-spots, and investigate the potential of biomass utilization for achieving carbon neutrality or even negative emissions. The analysis found that HGU’s main emissions were scope 1 emissions, primarily caused by on-site heat supply. The research determined that conversion to a wood chip-based heating system alone was insufficient to achieve climate neutrality, but this goal could be achieved through additional carbon dioxide removal (CDR). By operating a pyrolysis-based bivalent heating system, the study demonstrated that heat demand could be covered while producing sufficient C-sink certificates to transform HGU into the first carbon-negative HEI, at a comparable price to conventional combustion systems. Surplus C-sink certificates could be made available to other authorities or ministries. The results showed that bivalent heating systems can play an important role in HEI transitions to CO₂ neutrality by contributing significantly to the most urgent challenge of the coming decades: removing CO₂ from the atmosphere to limit global warming to as far below 2 °C as possible at nearly no extra costs. Full article

Carbon dioxide removal (CDR) systems are an integral part of sustainable pathways limiting global warming to less than 2.0 °C. When the sole purpose of CDR is capturing and storing atmospheric CO₂, carbon registries offer detailed procedures to calculate the carbon removal credits. However, the registries do not address how to distribute CO₂ flows when CDR provides additional services. Standardized, transparent rules for distributing CO₂ flows among CDR services are required for the formation of efficient private and public carbon markets. The lack of such rules could result in double counting if those reductions are allocated to more than one service, decreasing the trustworthiness of carbon removal credits or deterring the delivery of an additional low-carbon service, thus limiting the economic viability and deployment of CDR. We examine allocation rules in carbon registries and carbon accounting guidelines, including their life cycle assessment (LCA) principles. We evaluate physical (mass-based) and non-physical (economic) allocation methods using a generic CDR system and find both to be unworkable. We then develop a mass balance (MB) approach which can reliably allocate captured and stored carbon (CSC) between carbon removal credits and other services based on the value CO₂ removal in those markets. This practical approach to allocation can be used in a transparent way to provide flexibility that would allow CDR services to capture the value of the multiple services they provide and, through this, promote the deployment of these sustainable alternatives. Full article

In recent years, research on carbon dioxide removal (CDR) has significantly increased. Numerous studies have analyzed demonstration projects, outlined scenarios, modeled pathways, or focused on CDR’s national or international governance. However, regional case studies investigating the dynamics that may facilitate or impede the broader adoption of CDR methods in spatially explicit settings are critically absent. Understanding implementation contexts on the ground is vital, and comparing them across different removal methods is essential for effectively scaling up CDR. This paper aims to address this research gap by comparatively examining the development of biomass-based CDR in three regions of Germany. Taking an exploratory approach, we conducted surveys in these regions to gain insight into stakeholder perceptions of the following six CDR methods: forest management, agriculture and soil carbon, long-lasting building materials, rewetting of peatlands and paludiculture, biochar, and bioenergy with carbon capture and storage. In this article, we present the results of the stakeholder survey, which offers multiple perspectives that can shape future studies of regional implementation and yield policy-relevant guidance. Although our research primarily focuses on the regional level in Germany, it sheds light on various conflicts, uncertainties, and potentials that are likely to be relevant for the rollout of CDR in other countries. By examining these aspects, we contribute to the broader discourse on CDR and its potential implementation. Full article

In response to the urgent need to address climate change and reduce carbon emissions, there has been a growing interest in innovative approaches that integrate AI and CDR technology. This article provides a comprehensive review of the current state of research in this field and aims to highlight its potential implications with a clear focus on the integration of AI and CDR. Specifically, this paper outlines four main approaches for integrating AI and CDR: accurate carbon emissions assessment, optimized energy system configuration, real-time monitoring and scheduling of CDR facilities, and mutual benefits with mechanisms. By leveraging AI, researchers can demonstrate the positive impact of AI and CDR integration on the environment, economy, and energy efficiency. This paper also offers insights into future research directions and areas of focus to improve efficiency, reduce environmental impact, and enhance economic viability in the integration of AI and CDR technology. It suggests improving modeling and optimization techniques, enhancing data collection and integration capabilities, enabling robust decision-making and risk assessment, fostering interdisciplinary collaboration for appropriate policy and governance frameworks, and identifying promising opportunities for energy system optimization. Additionally, this paper explores further advancements in this field and discusses how they can pave the way for practical applications of AI and CDR technology in real-world scenarios. Full article

Solar geoengineering (SG) solutions have many advantages compared to the difficulty of carbon dioxide removal (CDR): SG produces fast results, is shown here to have much higher efficiency than CDR, is not related to fossil fuel legislation, reduces the GHG effect including water vapor, and is something we all can participate in by brightening the Earth with cool roofs and roads. SG requirements detailed previously to mitigate global warming (GW) have been concerning primarily because of overwhelming goals and climate circulation issues. In this paper, annual solar geoengineering (ASG) equations and estimated requirements for yearly solar radiation modification (SRM) of areas are provided along with the advantages of annual solar geoengineering (ASG) to mitigate yearly global warming temperature increases. The ASG albedo area modification requirements found here are generally 50 to potentially more than 150 times less compared to the challenge of full SG GW albedo mitigation, reducing circulation concerns and increasing feasibility. These reductions are applied to L1 space sunshading, Earth brightening, and stratosphere aerosol injection (SAI) SRM annual area requirements. However, SAI coverage compared to other methods will have higher yearly increasing maintenance costs in the annual approach. Results also show that because ASG Earth albedo brightening area requirements are much smaller than those needed for full mitigation, there are concerns that worldwide negative SG would interfere with making positive advances for several reasons. That is, negative SG currently dominates yearly practices with the application of dark asphalt roads, roofs, and building sides. This issue is discussed. Full article

Carbon dioxide removal (CDR) is gaining recognition as a necessary action in addition to emissions reduction to prevent some of the worst effects of climate change. Macroalgae aquaculture has been identified as a potential CDR strategy and significant research investments have been made in this area. This article reviews current methods for monitoring carbon to assess the potential for application in the context of macroalgae aquaculture as a CDR strategy. In total, 382 papers were included in the review and categorized by carbon uptake methods, carbon permanence methods, and comprehensive frameworks for assessing carbon capture. While methods for measuring carbon uptake are well established, methods to assess the permanence of carbon in the natural life cycle of macroalgae and in products following harvest are lacking. To achieve the full benefit of macroalgae cultivation as a climate solution, monitoring, reporting, and verification standards and improved methods for assessing carbon uptake and permanence need to be developed. Full article

The primary goal of the study was to determine the quantity of carbon accumulated in shallow fertile water bodies that were restored after a long period of drainage. Massive drainage of mid-field water bodies took place in north-eastern Poland in the 19th century. Of 143 identified drained lakes (each of more than 1 ha before drying) in the Olsztyn Lakeland, 27 have been restored to their original state through natural rewilding processes or recovery projects. From among the variety of drained water bodies, 8 which have been naturally or artificially restored to their original condition 13 to 47 years ago, were the subject of a detailed study on carbon sequestration. The studied water bodies had high productivity, and they were classified as moderately eutrophic to extremely hypertrophic. An analysis of bottom sediments revealed that, after restoration, the examined water bodies have accumulated 275.5 g C m⁻² a⁻¹ on average, which is equivalent to 10.1 Mg ha⁻¹ a⁻¹ of carbon dioxide (CO₂) removed from the atmosphere. Results showed that the evaluated water bodies are effective carbon sinks. Most of the lakes drained in the 19th century are wastelands today, and they can be relatively easily restored to their original condition to create additional carbon sequestration sites. Lake restoration seems to be a cost-effective method both for carbon capture (as additional potential capacity as part of carbon dioxide removal (CDR) methods) and to support the sustainable use of agricultural areas. However, this second goal may be limited by the poor ecological status of such facilities. Full article