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The economic feasibility of retrofitting an amine based post-combustion CO 2 capture process to an existing Kraft pulp mill and an existing integrated pulp and board mill has been assessed. This study builds on the technical assessment of the energy performance of the mills when retrofitting a post-combustion CO 2 capture process by Onarheim et al. (2017). Between 75 to 100% of the CO 2 emissions from the pulp and paper industry originate from the combustion of biomass. If the raw material is sourced sustainably, these emissions are categorized as carbon neutral. Applying sustainably managed biomass in the pulp and paper processes and capturing the resulting CO 2 for permanent storage enables the industry to go carbon negative. In this study, the economic impact of retrofitting CO 2 capture from the flue gases of the recovery boiler, the multi-fuel boiler and the lime kiln were assessed. The levelized cost of pulp and the cost of CO 2 avoided were evaluated based on six different scenarios varying the CO 2 tax, incentives for renewable electricity production, with and without recognizing biogenic CO 2 emissions as neutral (exempting CO 2 emissions from tax or not), and rewarding captured and permanently stored CO 2 with negative emissions credit. Results show that the pulp and paper industry has a potential for realizing feasible implementation of large-scale industrial Bio-CCS. For cases where 60–90% of total site CO 2 emissions are captured, the cost of avoided CO 2 amounts to 52–66 €/t for the Kraft pulp mill and 71–89 €/t for the integrated pulp and board mill. The cost of avoided CO 2 , and thus the realization of Bio-CCS in the pulp and paper industry, is strongly dependent on prevailing policy frameworks such as the EU ETS. In order to reach a levelized cost of pulp similar to the reference mill without CO 2 capture, a negative CO 2 emission credit of 60–70 €/t CO 2 for the Kraft pulp mill and 70–80 €/t CO 2 for the integrated pulp and board mill will be required. As long as biogenic CO 2 emissions that are captured and permanently stored are not recognized as negative and rewarded accordingly there is no economic incentive for the owners of pulp and paper mills to implement CCS. The only way to get the pulp and paper industry to implement and deploy Bio-CCS will need the support of the decision-makers in promoting the right policy framework and regulations to encourage the investment such as strong incentives for negative emissions which are bankable during the long term operation of the mills. [ABSTRACT FROM AUTHOR]

In order to meet the IPCC recommendation for an 80% cut in CO 2 emissions by 2050, industries will be required to drastically reduce their emissions. To meet these targets, technologies such as carbon capture and storage (CCS) must be part of the economic set of decarbonisation options for industry. A systematic review of the literature has been carried out on four of the largest industrial sectors (the iron and steel industry, the cement industry, the petroleum refining industry and the pulp and paper industry) as well as selected high-purity sources of CO 2 from other industries to assess the applicability of different CCS technologies. Costing data have been gathered, and for the cement, iron and steel and refining industries, these data are used in a model to project costs per tonne of CO 2 avoided over the time period extending from first deployment until 2050. A sensitivity analysis was carried out on the model to assess which variables had the greatest impact on the overall cost of wide-scale CCS deployment for future better targeting of cost reduction measures. The factors found to have the greatest overall impact were the initial cost of CCS at the start of deployment and the start date at which large scale deployment is started, whilst a slower initial deployment rate after the start date also leads to significantly increased costs. [ABSTRACT FROM AUTHOR]

The performance of an amine-based post-combustion CO 2 capture and storage (CCS) process in an existing Kraft pulp mill and an existing pulp and board mill was assessed. The pulp and paper industry is an energy-intensive industry, with significant amounts of CO 2 emitted onsite. The majority of this CO 2 originates from the combustion of biomass, which renders it carbon neutral if the biomass used by the industry is grown and harvested in a sustainable manner. If the CO 2 emissions from the pulp and paper industry were to be captured and permanently stored, then this could make the industry a potential carbon sink. In this evaluation, different configurations of capturing CO 2 from the flue gases of the recovery boiler, the multi-fuel boiler and the lime kiln were assessed. For a stand-alone Kraft pulp mill, the excess steam available is sufficient to cover the demand from the CO 2 capture plant. For an integrated pulp and board mill, there is less excess steam available for the CO 2 capture plant and an auxiliary boiler may be required. The retrofit of a post-combustion CO 2 capture plant into an existing pulp mill increases the steam demand by 1–8 GJ/air dried tonne (adt) pulp, depending on the volume of the flue gas treated. This translates to a reduction in the amount of electricity exported to the grid by 0.1–1.0 MWh/adt pulp for a stand-alone Kraft pulp mill, and by 0.1–0.5 MWh/adt pulp for an integrated pulp and board mill. The total potential for negative CO 2 emissions amounts to just under 2.0 Mt CO 2 /a both for the market pulp mill and for the integrated pulp and board mill. [ABSTRACT FROM AUTHOR]

A scalable papermaking process was employed herein to manufacture cellulosic papers from native and phosphorylated cellulose microfibers (referred to as CMF and PCMF, respectively) impregnated with polyethyleneimine (PEI) for Direct Air Capture (DAC) applications. These papers were analyzed in terms of their physico-chemical properties using several techniques. The impact of PEI content on desorbing the co-adsorbed H 2 O and CO 2 from the air, as well as on the anisotropic microporous network, was explicitly analyzed. The results indicated that phosphorylation promotes the uptake of both CO 2 and H 2 O in the corresponding neat and PEI-loaded papers, reaching a superior CO 2 adsorption capacity of ∼0.7–0.9 mmol.g−1 for PCMF papers versus 0.07–0.3 mmol.g−1 for CMF papers. Furthermore, the CMF and PCMF papers exhibited H 2 O adsorption capacities in the range of 1.5–1.8 mmol.g−1 and 2.2–3.8 mmol.g−1, respectively. This work further highlights the combined role of phosphorylation and favorable PEI impregnation in tuning the cellulose CO 2 adsorption properties under humid conditions, facilitating the rapid release of the adsorbed CO 2 under mid conditions. [Display omitted] • Manufacturing of scalable solid cellulosic papers with amine functionalities and enhanced carbon capture. • Microstructural and chemical characterization of amine functionalized paper with various amine ratios. • Valorization of Alfa biomass in Carbon capture applications. • The combined role of phosphorylation and PEI impregnation in tuning the H 2 O and CO 2 co-adsorption properties. [ABSTRACT FROM AUTHOR]

• Black liquor gasification was coupled with calcium looping. • Calcium looping for CO 2 capture and H 2 production was compared. • CO 2 capture route (39 €/t) was less expensive than H 2 production route (48.8 €/t). • CO 2 avoided cost was highly dependent on capital cost of black liquor gasification. • Export of H 2 had the lowest CO 2 avoided cost among black liquor gasification cases. Although considered one of the major energy-intensive industries (EIIs), the pulp and paper industry has also the potential for energy production from an industrial waste, black liquor. This study proposes black liquor gasification (BLG) coupled with calcium looping (CaL) as a CO 2 capture route for the pulp and paper industry. BLG with H 2 production (BLG-CaL-H 2), BLG with gas turbine combined cycle (BLG-CaL-GT) or with solid oxide fuel cell (BLG-CaL-SOFC) were considered. The dependence of carbon capture and storage (CCS) cost on the natural gas, limestone, electricity imported and H 2 sale prices aside the expenditures related with BLG-CaL were evaluated. The CCS route, based on CaL retrofitted to the pulp and paper plant, was found to have a lower cost of CO 2 avoided (39.0 €/tCO 2) when compared with BLG-CaL (48.8–57.1 €/tCO 2). Between the BLG-CaL scenarios, BLG-CaL-H 2 presented the lowest cost of CO 2 avoided (48.8 €/tCO 2) but the highest energy penalty. Based on the thermodynamic performance, it was shown that CaL retrofit and BLG-CaL-SOFC presented the best overall performance, turning the electricity importer reference plant into electricity exporter. The economic sensitivity showed that the capital requirement of BLG-CaL has a strong effect on the cost of CO 2 avoided for all alternatives. The H 2 production is also strongly affected by the H 2 sale price while BLG-CaL-SOFC and BLG-CaL-GT are strongly dependent on natural gas price. [ABSTRACT FROM AUTHOR]

Abstract: Carbon capture and storage (CCS) is one of a suite of technology options that might play a significant role in reducing greenhouse gas emissions. However, outside of traditional enhanced oil and gas recovery operations with a well established business model, CCS project deployments are struggling with adoption of a federal or international climate policy driver appearing unlikely for the foreseeable future. As part of a feasibility study for an industrial CCS project at the Boise White Paper mill in Washington State, a business model and CCS system design was developed that provided financial surety for the project developers while recognizing that uncertainty in revenue forecasts for CO2 storage would persist for the foreseeable future. Key to the business model was installation of a new 37MWe biomass-fueled power island at the plant that would replace antiquated boilers and that could still supply the necessary steam to run pulp and paper production operations when capturing CO2 emissions under favorable market conditions for monetizing CO2 storage credits. Under unfavorable market conditions, CO2 capture would be suspended and excess power generated from the plant would reduce external electrical energy purchases required for paper mill operations. The net CO2 reduction for the project versus current operations is 1.0MMT of CO2 per year with the CCS system online, and 139ktons per year with the CCS system offline due to reduced natural gas co-firing. So, both operational modes offered a significant net reduction in CO2 emissions. Based on assumptions regarding electricity and natural gas pricing, and CO2 storage revenue generated through an open market mechanism priced at $15 per metric ton CO2, the payback period for the project capturing 0.5MMT/yr (62% of total CO2 production) was estimated at 6.7 years versus 7.4 years with the CCS system offline. Geologic storage was evaluated in the deep flood basalt formations that dominate the storage capacity in Eastern Washington. Sub-basalt sediments were also examined at the site to provide alternative or supplemental storage capacity in the event that storage in the basalt sequences did not prove technically or economically feasible. [Copyright &y& Elsevier]

• The hygroscopic property of paper fiber is used to prepare a bifunctional catalyst. • The impregnation time for preparing the hollow microtubular Ni-MgO-CaO is 1 min. • 94.1 % of hydrogen is stably produced on 5Ni-10MgO-CaO from biogas for 50 cycles. • Only 37.1 % loss of the sorption-enhanced effect is shown during the entire cycle. Sorption-enhanced steam reforming (SESR) process is a promising technology aiming at the production of high purity hydrogen with CO 2 capture. The key to the success of this process is the availability of high-performance bifunctional catalysts. Herein, we develop a hollow microtubular Ni-MgO-CaO bifunctional catalyst with paper fiber as template. Due to the strong hygroscopic properties of paper fibers, it provides a method for the rapid synthesis of catalysts with design components by adsorbing solution. The characterizations indicate that the impregnation time (1 min vs 24 h) has no effect on the structural properties of Ni-MgO-CaO bifunctional catalysts. MgO as an inert spacer can weaken the sintering of CaO to ensure a stable CO 2 uptake. Moreover, the agglomeration of Ni particles is inhibited by the MgO coating on their surface. 5Ni-10MgO-CaO as the best performing catalyst displays high stability for the SESR of biogas (SESRB) reaction, during which 94.1 % purity of hydrogen with a 95.2 % conversion of CH 4 is stably produced and only 37.1 % decrease of sorption-enhanced effect is observed in 50 SESRB-calcination cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mixed sludge from pulp and paper mill wastewater treatment was treated with HTC. • HTC enhanced energy recovery in hydrochars having 37% increased heating value. • No significant sludge dewaterability improvement was observed after HTC. • HTC increased filtrate organics content and volumetric methane production potential. • Mixed sludge hydrochars are potential for carbon sequestration. The pulp and paper industry's mixed sludge represents waste streams with few other means of disposal than incineration. Hydrothermal carbonization (HTC) could be advantageous for the sludge refinement into value-added products, thus complementing the concept of pulp and paper mills as biorefineries. Laboratory HTC was performed on mixed sludge (at 32% and 15% total solids) at temperatures of 210–250 °C for 30 or 120 min, and the characteristics of the HTC products were evaluated for their potential for energy, carbon, and nutrient recovery. The energy content increased from 14.9 MJ/kg in the mixed sludge up to 20.5 MJ/kg in the hydrochars. The produced filtrates had 12–15-fold higher COD and 3–5-fold higher volumetric methane production than untreated sludge filtrates, even though the methane yield against g-COD was lower. The increased value of the hydrochars in terms of energy content and carbon sequestration potential promote HTC deployment in sludge treatment and upgrading. [ABSTRACT FROM AUTHOR]

In this paper an approach for analysing the potential for implementation of different technology pathways for the European pulp and paper industry (PPI) is presented. The approach is based on detailed technical research and aggregates the knowledge from previous studies to incorporate the whole European PPI. Thus, the potential for different technology pathways can be estimated on a European level whilst still considering important characteristics of individual mills. The usefulness of the approach was exemplified by applying it to a case study of the potential for introduction of carbon capture and storage (CCS) within the European PPI. The results from the case study show that for the European PPI, CCS has an up-hill road in order to be a viable, large scale alternative for reduction of CO2 emissions. If CCS is to be introduced in large scale within the European PPI, large biomass-based point sources of CO2 emissions need to be included when planning for CCS infrastructure and also the infrastructure needs to be built out for clusters emitting <20 MtCO2/yr. [ABSTRACT FROM AUTHOR]

Pulp and paper is considered to be the fourth most energy-intensive industry (EII) worldwide. However, as most of the CO 2 emissions are of biomass origin, this sector has the potential to become a carbon-negative industry. This study proposes a new concept for conversion of the pulp and paper industry to carbon negative that relies on the inherent CO 2 capture capability of the Kraft process. The techno-economic performance of the proposed carbon-negative system, based on calcium looping (CaL) retrofitted to a pulp and paper plant, was evaluated. The effect of CaL design specifications and cost assumptions on the thermodynamic and economic performance were evaluated. Under the initial design assumptions, the reference pulp and paper plant was shown to turn from electricity importer to electricity exporter with the cost of CO 2 avoided equal to 39.0 €/tCO 2. The parametric study showed that an increase in the fresh limestone make-up rate resulted in a linear increase of the specific primary energy consumption for CO 2 avoided (SPECCA) and a reduction in the amount of electricity exported to the electric grid. This translates into an increase in the price of pulp and newsprint, and the cost of CO 2 avoided. This study has also demonstrated that the pulp and paper industry has high potential to become carbon negative. It has been shown that carbon capture and storage would become economically viable in this industry if the negative CO 2 emissions are recognised and a negative CO 2 emissions credit of at least 41.8 €/tCO 2 is implemented. • Concept of the Kraft process with inherent CO 2 capture. • Calcium looping for CO 2 capture is integrated in the lime cycle. • Reference pulp and paper plant turns from importer to exporter of electricity. • Pulp and paper industry has a high potential to become carbon negative. • Economic feasibility needs the inclusion of biogenic emissions in emission trading. [ABSTRACT FROM AUTHOR]

The objective of this study was to measure the anaerobic biodegradation of different types of paper products in laboratory-scale landfill reactors. The study included (a) measurement of the loss of cellulose, hemicellulose, organic carbon, and (b) measurement of the methane yields for each paper product. The test materials included two samples each of newsprint (NP), copy paper (CP), and magazine paper (MG), and one sample of diaper (DP). The methane yields, carbon storage factors and the extent of cellulose and hemicellulose decomposition all consistently show that papers made from mechanical pulps (e.g., NPs) are less degradable than those made from chemical pulps where essentially all lignin was chemically removed (e.g., CPs). The diaper, which is not only made from chemical pulp but also contains some gel and plastic, exhibited limited biodegradability. The extent of biogenic carbon conversion varied from 21 to 96% among papers, which contrasts with the uniform assumption of 50% by the Intergovernmental Panel on Climate Change (IPCC) for all degradable materials discarded in landfills. Biochemical methane potential tests also showed that the solids to liquid ratio used in the test can influence the results. [ABSTRACT FROM AUTHOR]

Hydrogen Economy and Cyclic Economy are advocated, together with the use of perennial (solar, wind, hydro, geo-power, SWHG) and renewable (biomass) energy sources, for defossilizing anthropic activities and mitigating climate change. Each option has intrinsic limits that prevent a stand-alone success in reaching the target. Humans have recycled goods (metals, water, paper, and now plastics) to a different extent since very long time. Recycling carbon (which is already performed at the industrial level in the form of CO 2 utilization and with recycling paper and plastics) is a key point for the future. The conversion of CO 2 into chemicals and materials is carried out since the late 1800s (Solvay process) and is today performed at scale of 230 Mt/y. It is time to implement on a scale of several Gt/y the conversion of CO 2 into energy products, possibly mimicking Nature which does not use hydrogen. In the short term, a few conditions must be met to make operative on a large scale the production of fuels from recycled-C, namely the availability of low-cost: i. abundant, pure concentrated streams of CO 2 , ii. non-fossil primary energy sources, and iii. non-fossil-hydrogen. The large-scale production of hydrogen by Methane Steam Reforming with CO 2 capture (Blue-H 2) seems to be a realistic and sustainable solution. Green-H 2 could in principle be produced on a large scale through the electrolysis of water powered by perennial primary sources, but hurdles such as the availability of materials for the construction of long-living, robust electrochemical cells (membranes, electrodes) must be abated for a substantial scale-up with respect to existing capacity. The actual political situation makes difficult to rely on external supplies. Supposed that cheap hydrogen will be available, its direct use in energy production can be confronted with the indirect use that implies the hydrogenation of CO 2 into fuels (E-fuels), an almost ready technology. The two strategies have both pros and cons and can be integrated. E-Fuels can also represent an option for storing the energy of intermittent sources. In the medium-long term, the direct co-processing of CO 2 and water via co-electrolysis may avoid the production/transport/ use of hydrogen. In the long term, coprocessing of CO 2 and H 2 O to fuels via photochemical or photoelectrochemical processes can become a strategic technology. • Hydrogen Economy and Cyclic Economy are discussed as an option for defossilizing anthropic activities and mitigating climate change. • In the short term, a few conditions must be met to make operative on a large scale the production of fuels from recycled-C. • In the medium-long term, the direct co-processing of CO 2 and water via co-electrolysis may avoid the production/transport/ use of hydrogen. • In the long term, coprocessing of CO 2 and H 2 O to fuels via photochemical or photoelectrochemical processes can become a strategic technology. [ABSTRACT FROM AUTHOR]

Strategies for changing the conductivity of Li 2 CO 3 is introduced into the fabrication of Li-CO 2 battery. Benefitting from the favorable hierarchical architecture constructed (CPM-MnO 2), facile charge transfer occurs between catalytic surface and Li 2 CO 3 by –OH⋯O hydrogen bonds improves the metallicity of Li 2 CO 3 , facilitating the formation/decomposition of Li 2 CO 3 and bestowing an ultra-long-term stability of 1087 cycles (4348 h). Taking into account its simplicity, scalable character and outstanding performance, this hierarchical composite electrode paves an effective trajectory for the future development of highly efficient cathodes for durable metal-CO 2 batteries. [Display omitted] • Excellent hierarchical structure of MXene and MnO 2 on carbon paper was fabricated. • Enriched charge transfer occurred on MXene and the MnO 2 by OH⋯O hydrogen bonding. • The prepared batteries showed an ultra-long cycle lifetime and low overpotential. • The optimized electronic structure can improve the metallicity of Li 2 CO 3. • The accelerated decomposition of discharge products promoted CRR and CER kinetics. Lithium-CO 2 batteries are recognized as an essential strategy for efficient carbon sequestration and energy storage to achieve carbon neutrality. Their cycle-ability and polarization voltage, however, are hindered by high decomposition voltage (≈4.3–4.5 V) of insulating Li 2 CO 3. Herein, we report a significant advance toward the rational design of self-supporting and ultra-long cycle lifetime cathode for Li-CO 2 batteries, dependence on a favorable hierarchical architecture and rich charge transfer constructed by homogeneously distributed MnO 2 nanoplates rooted in the MXene surface supported by carbon paper. Detailedly, it exhibits impressive ultra-long-term stability of 1087 cycles (4348 h) with a low polarization gap (≈ 0.47 V) at a high current of 200 μA cm−2, which is outperformed by all the liquid electrolyte-based Li-CO2 batteries reported previously. Electronic structure analysis reveals that facile charge transfer occurs between catalytic surface and Li 2 CO 3 , springing from the –OH functional group (in MXene) to MnO 2 by –OH⋯O hydrogen bonds, which acts as charge transfer channels, improving the metallicity of Li 2 CO 3 and facilitating its decomposition and extending battery cyclability. This work paves an effective trajectory for the future development of highly efficient cathodes for durable metal-CO 2 batteries. [ABSTRACT FROM AUTHOR]

Abstract: In this study, experiments were conducted to investigate the applicability of low-cost alkaline paper mill wastes as acidity neutralizing agents for treatment of acid mine drainage (AMD). Paper wastes include a calcium mud by-product from kraft pulping, and a calcite powder from a previous study focused on sequestering CO2 by carbonation of calcium mud. The neutralization process consisted of increase of pH by alkaline additive dissolution, decrease of metals solubility and precipitation of gypsum and poorly crystallized Fe–Al oxy-hydroxides/oxy-hydroxysulphates, which acted as a sink for trace elements to that extent that solutions reached the pre-potability requirements of water for human consumption. This improvement was supported by geochemical modelling of solutions using PHREEQC software, and observations by scanning electron microscope and X-ray diffraction of reaction products. According to PHREEQC simulations, the annual amount of alkaline additive is able to treat AMD (pH 3.63, sulphate 3800mgL−1, iron 348mgL−1) with an average discharge of about 114 and 40Ls−1 for calcium mud and calcite powder, respectively. Likewise, given the high potential of calcium mud to sequester CO2 and of resulting calcite powder to neutralize AMD, paper wastes could be a promising solution for facing this double environmental problem. [Copyright &y& Elsevier]

In recent years, the utilization of biomass through advanced power technologies has intensified to achieve carbon neutrality. An oxy-fuel circulating fluidized bed combustor of biomass with higher efficiency supercritical carbon dioxide cycle has been developed with the aim of compensating the penalties for carbon capture and storage. The combustor fuelled with waste paper, waste wood, and cow manure, at an input of 200 ton/day is economically evaluated. Waste paper is on the verge of becoming an economically feasible fuel, more so than the other biomass examined. The use of waste paper led to a positive net present value, an internal rate of return of 3.8%, a benefit-cost ratio of 1.025, and a payback period of 17.7 years. Subsequent sensitivity analyses conducted for the waste paper fuelled power plant indicated that the capital cost is the most influential factor; the boiler, supercritical carbon dioxide cycle, and oxygen fuel combustion system were indicated in descending order of related subdivided sensitiveness. Both renewable energy certificate and carbon credit has contributed to the feasible economic of the system, with former one took precedence over later one. Sensitivity from the technical perspective, improvement in air separation unit is likely to greatly improve the economic feasibility of the proposed system. The power consumption of the air separation unit, as well as that of the carbon dioxide compression and purification unit, were highly sensitive to the implementation cost. [Display omitted] • Integration of oxygen combustion and supercritical carbon dioxide power cycle. • Economic feasibility study of integrated biomass circulating fluidized bed. • Capital cost demonstrated the foremost sensitivity factor. • Waste paper as potential economically feasible fuel. • Innovation in air separation unit improves economic feasibility. [ABSTRACT FROM AUTHOR]

Post-combustion capture (PCC) of CO 2 from fossil fuel-fired power station flue gas is one of many technologies that are being developed to reduce anthropogenic greenhouse gas emissions in the medium term. Wet-gas scrubbing using aqueous amines is currently the most mature PCC technology suitable for separating CO 2 from coal-fired power station flue gases. In this study, a series of twelve samples of a degraded 30% (w/w) MEA absorbent were obtained over a six month pilot scale PCC campaign at a brown coal-fired power station in Australia. These samples were used to investigate the accumulation of heat-stable salts, inorganics and minerals. The heat-stable salts concentration increased from 0.80 to 2.29% (w/w, as MEA) and organic acids from the oxidative degradation of MEA were the largest component of heat-stable salts. Acid gases such as SO x and NO x , make-up water, ultra-fine fly-ash and corrosion were all sources of the minerals and inorganics that accumulated in the aqueous MEA absorbent. Corrosion was the single biggest contributor of transition metals and the abrupt change in ratios of Fe, Cr and Mo suggests that the dominant corrosion mechanism may have changed towards the end of the campaign. The rapid accumulation of minerals and inorganics during this PCC campaign highlights the importance of continuing research into the interactions between amine absorbents and inorganic or mineral contaminants. The data presented in this study are an important resource for design of laboratory scale experiments to investigate these physical and chemical interactions between aqueous amines, minerals and inorganics. [ABSTRACT FROM AUTHOR]

This paper explores green hydrogen-based carbon dioxide (CO 2) hydrogenation for the production of oxygenates, presenting it as a pivotal strategy for mitigating carbon emissions and advancing sustainable energy solutions. The conversion of CO 2 into oxygenates through hydrogenation emerges as a promising avenue, particularly in the context of transportation applications where the storage of hydrogen poses challenges. The substitution of fossil diesel and gasoline fuels with green hydrogen-derived dimethyl ether, or methanol/ethanol, is advantageous from a life cycle analysis (LCA) CO 2 emission perspective even without the capture of the CO 2. However, the greatest sustainability appeal is contingent on the crucial aspect of capturing CO 2 when utilizing these fuels, which is an aspect currently absent in the literature. This narrative review comprehensively explores catalytic processes, mechanisms, sustainability perspectives, and the current state of research in this evolving area. It encompasses both the production of oxygenates through CO 2 hydrogenation and the subsequent utilization of these oxygenates in fuel cells or combustion systems, emphasizing the integration of CO 2 capture technologies. The paper contributes to the discourse surrounding the environmental and technological dimensions of energy storage ecosystems, providing a holistic view of their potential to foster sustainable energy solutions. [ABSTRACT FROM AUTHOR]

Photocatalytic reduction of CO 2 is a promising technology to capture CO 2 and convert it into solar fuels simultaneously. However, current photoreactors usually face the problems of low specific surface area, non-uniform light distribution and poor photon transfer. To address these issues, a novel optofluidic membrane microreactor with high surface-area-to-volume ratio, enhanced photon and mass transport and uniform light distribution was proposed in this work by combining optofluidics with the membrane reactor technology for the photocatalytic reduction of CO 2 with liquid water. A TiO 2 /carbon paper composite membrane was prepared as the photocatalytic membrane via coating TiO 2 onto the carbon paper followed by hydrophobic treatment by poly-tetrafluoroethylene (PTFE) for the separation of the gas/liquid phases. The performance of the proposed optofluidic membrane microreactor was evaluated by measuring the methanol yield. The effects of the liquid water flow rate, light intensity and catalyst loading on the methanol yield were also studied. It was shown that a maximum methanol yield of 111.0 μmole/g-cat·h was achieved at a flow rate of 25 μL/min and under the light intensity of 8 mW/cm 2 , which is among the top in comparison to the reported data. Results obtained fully demonstrate the feasibility and superiority of the proposed optofluidic membrane microreactor for the photocatalytic reduction of CO 2 . [ABSTRACT FROM AUTHOR]

In continuation of the previous part, this paper comprehensively focuses on energy, exergy, exergo-economic, and environmental (4E) analyses of two prioritized clean hydrogen (H 2) supply chains pathways. The first scenario relies on domestic demand , involves blue H 2 production and storage using steam methane reforming coupled with carbon capture and storage through H 2 conversion to hydrogen carriers in liquid form (ammonia and methanol) aligned with the existing infrastructure. The second scenario involves green H 2 production from photovoltaic panels as the power source follows by storing H 2 in liquid form which is more suitable to export. The findings indicate that the blue H 2 system outperforms the green H 2 system in terms of energy and exergy, boasting 41.38% and 22.15% compared to 12.16% and 12.75%, respectively. However, when examining economic parameters, the blue H 2 system shows a total cost rate of 1976 US$/h, a net profit of $747.2 million (mn) at the end of its lifetime, and a payback period of approximately nine years. Conversely, the green H 2 system demonstrates economic indicators of a 125.2 $/h as a total cost rate, $1.26 billion (bn) net profit, and an 8.17 year payback period. Moreover, the production cost rates for blue and green H 2 are 1.32 $/kg and 2.55 $/kg, respectively; while the CO 2 emissions rate in the blue H 2 system is 10.71 kg/s. The green H 2 system prevents 19.84 kg/s of CO 2 emissions resulted a significant environmental cost reduction of 2.28 $/kg H 2. This analysis facilitates a thorough comparison of these two clean H 2 production and storage systems, offering insights for policymakers across performance, economic, and environmental dimensions. • A comprehensive 4E analysis was applied for the selected H 2 value chain scenarios. • Blue H 2 scenario is superior economically while environmentally the green one takes precedence. • Carbon credit makes the green H 2 scenario emerges frontrunner utilizing PV solar technology. • Methanol was recognized as the most cost-effective H 2 carrier for storage in Iran. [ABSTRACT FROM AUTHOR]

Business-as-usual (BAU) cement production is associated with a linear model that contributes significantly to global warming and is dependent on volatile energy markets. A novel circular model is proposed, by adding three power-to-gas system components to current production systems: a calcium-looping (CaL) CO 2 capture unit; water electrolysis for hydrogen and oxygen generation; and a methanation unit for synthetic natural gas (SNG) production. The paper presents the first analysis of the combined industrial-scale operation of these components in a closed loop, where the SNG fuels the cement kiln and the CaL unit, while the O 2 produced feeds it. The circular, hybrid, and BAU models are compared in three feasibility scenarios. It is concluded that the circular model outperforms the other alternatives environmentally, opening a potential pathway for the cement industry to achieve near net-zero CO 2 emissions, reduce energy dependence and improve economic efficiency. [Display omitted] • Innovative circular model proposed for carbon-neutral cement production. • Novel integration of CaL CO 2 capture, water electrolysis and methanation units. • Comparative techno-economic and environmental analysis conducted. • Circular model outperformed current and hybrid models. • Near net-zero CO 2 emissions and increased energy independence achieved. [ABSTRACT FROM AUTHOR]

• A review with over 300 references on the utilization of challenging ashes. • Metal and phosphorus recovery from different ashes was addressed. • The key beneficial properties of biomass and MSW ashes were identified. In line with the objectives of the circular economy, the conversion of waste streams to useful and valuable side streams is a central goal. Ash represents one of the main industrial side-products, and using ashes in other than the present landfilling applications is, therefore, a high priority. This paper reviews the properties and utilization of ashes of different biomass power plants and waste incinerations, with a focus on the past decade. Possibilities for ash utilization are of uttermost importance in terms of circular economy and disposal of landfills. However, considering its applicability, ash originating from the heat treatment of chemically complex fuels, such as biomass and waste poses several challenges such as high heavy metal content and the presence of toxic and/or corrosive species. Furthermore, the physical properties of the ash might limit its usability. Nevertheless, numerous studies addressing the utilization possibilities of challenging ash in various applications have been carried out over the past decade. This review, with over 300 references, surveys the field of research, focusing on the utilization of biomass and municipal solid waste (MSW) ashes. Also, metal and phosphorus recovery from different ashes is addressed. It can be concluded that the key beneficial properties of the ash types addressed in this review are based on their i) alkaline nature suitable for neutralization reactions, ii) high adsorption capabilities to be used in CO 2 capture and waste treatment, and iii) large surface area and appropriate chemical composition for the catalyst industry. Especially, ashes rich in Al 2 O 3 and SiO 2 have proven to be promising alternative catalysts in various industrial processes and as precursors for synthetic zeolites. [ABSTRACT FROM AUTHOR]

Aiming at the excessive power fluctuation of large-scale wind power plants as well as the consumption performance and economic benefits of wind power curtailment, this paper proposes a hybrid energy storage capacity configuration strategy for virtual power plants based on variable-ratio natural gas-hydrogen blending. Firstly, a natural gas-hydrogen blending virtual power plant architecture with the synergy of power-to-gas and carbon capture is established in terms of low-carbon performance, and then a natural gas-hydrogen blending capacity configuration with the synergy of carbon capture and power-to-gas is carried out for the architecture. Secondly, the mathematical modeling is carried out for the liquid storage carbon capture, power-to-gas, hydrogen storage, flywheel energy storage, hydrogen blending gas turbine and hydrogen blending gas boiler. Finally, the objective function of minimizing the cost of carbon trading and storage, the cost of startup and shutdown of coal-fired units and the cost of coal consumption, the cost of wind power curtailment, the cost of purchasing gas, the cost of power-to-gas, the cost of hydrogen blending, and the cost of hydrogen blending is proposed based on the modelings. After the linearization of the models, the Gurobi commercial solver was invoked through MATLAB software to solve the model, and five scenarios were set up for comparative analysis. The results further verified the effectiveness of the proposed strategy. • Empirical mode decomposition algorithm is used to achieve wind power decomposition. • Flywheel energy storage is configured to suppress the wind power. • In-depth analysis of hydrogen blending ratios improves economic benefits. [ABSTRACT FROM AUTHOR]

The transition to increasingly renewable electricity grids and the electrification of industrial processes are two recent developments promising to be potential solutions towards net zero in industrial production processes. Generally, grid electricity is perceived as a stable and reliable resource that can be accessed on demand. However, that is not always the case for large industrial users (100 MW+), and a key future challenge that must be overcome is the inherent uncertainty of the electricity supply by renewable sources, as well as in pricing. In methanol production, the concept of using electrolysis and CO2 capture is being explored as a way of replacing reforming to produce syngas for "green" methanol production. With the omission of the reforming process which supplies energy as steam for the process, there is now a need to electrify the affected downstream unit operations. Distillation is a key unit operation in chemical operations that consumes large amounts of energy for reboiler duty and holds the key to making on-specification AA-grade methanol, a precursor chemical. With the volatility of the electricity market, hence supply, these columns must be able to withstand a sudden large reboiler duty drop. This paper developed a novel process operations and control principle to allow for the flexible operation of a high-purity methanol distillation column in volatile energy markets. At its core is the concept of using a distillation column as a "process battery". Results obtained from a validated process simulation show that the novel "process battery" operations principle can withstand a supply-side change as great as 75% within a time span of 5 min without breaking complex quality and performance specifications of the column. This control philosophy is a major departure from the traditional process control and operating regimes that are focused on maintaining steady operations under all conditions. • Novel control philosophy developed for flexible operation of high-purity methanol distillation in volatile energy markets. • A major change from traditional operations and control focused on maintaining steady operations under all conditions. • The concept of using a distillation column as a "process battery" is defined. • Validated process simulation results show the strategy withstands large supply-side changes without breaking specifications. [ABSTRACT FROM AUTHOR]

CO 2 sequestration is an effective technology for reducing greenhouse gas effect. To ensure the safety, assessment of well applicability should be conducted before CO 2 sequestration. However, current studies mainly focus on identifying which barrier has the highest risk of leakage rather than selecting a target well for injection in specific geological formation. To further investigate, this paper proposes well applicability assessment method combining reservoir and wellbore properties together for CO 2 sequestration. A novel assessment system combing Fuzzy comprehensive evaluation and Analytic hierarchy process has been established. Twenty-nine indexes subjected to seven categories (i.e., formation, well, cement sheath, cementing quality, casing, tubing, and wellhead properties) are taken into consideration. The weighting factors of these seven categories are 0.0673, 0.0552, 0.096, 0.1537, 0.2283, 0.2637 and 0.1369, respectively. Tubing and casing properties have the greatest influence on safety injection. Furthermore, the proposed system has been applied to S gas reservoir, China. Results show that Wells #P1 and #P2 are suitable for injection. Since more comprehensive indicators are considered comparing with previous studies, the results are more accuracy and objective. The findings of this paper could help efficiently and effectively evaluating well applicability for CO 2 sequestration and reducing the risk of CO 2 leakage. [ABSTRACT FROM AUTHOR]

During the use of compressed CO 2 storage in saline aquifers, complex geochemical reactions may occur, affecting the petrophysical properties of the reservoir rocks and leading to CO 2 depletion. In this paper, the geochemical reaction mechanism of CCES-SA was studied numerically with the Yingcheng Group in the southeast uplift area of the Songliao Basin as the study area. The hydrogeological parameters of the target study area were used as the initial parameters for the numerical simulation study, and the CO 2 -brine-rock geochemical reaction simulation was carried out using the reaction transport model to study the effects of the 20-year geochemical reaction on the physical properties of reservoir rocks and CO 2 consumption through numerical simulation. The following results were obtained by analyzing the numerical simulation results. The long-term geochemical reactions dissolved chlorite and feldspar minerals, etc., and also precipitated carbonates and clay minerals, etc., which were consistent with the actual results. Besides, the dissolution and precipitation of the above minerals did not affect the porosity and permeability of underground aquifers and did not have adverse consequences for extraction. At the end of 20 years of inter-seasonal energy storage, the percentages of CO 2 captured in gas, aqueous phase and minerals were 27%, 65% and 8%, respectively. During storage, it was recommended to inject CO 2 appropriately during closure to maintain gas phase CO 2 content and pressure. During the production process, the acidified formation fluid came into contact with the inner pipe, increased the risk of wellbore corrosion. When selected materials for wellbore materials, it was recommended to choose corrosion-resistant pipes. What was studied in this paper could provide a theoretical reference for underground energy storage projects involving fluid-rock interactions. [ABSTRACT FROM AUTHOR]

Hydrogen is a versatile energy carrier and storage medium that is expected to have a key role in the energy transition, as it can be employed in a variety of applications. Hydrogen can be produced from different feedstocks and using different processes. Based on the production technology used, hydrogen is conventionally identified by a color. In this work, we compare different hydrogen generation processes: (i) green hydrogen, obtained by electrolysis of water using electricity from floating photovoltaic platforms, (ii) grid hydrogen, also obtained by electrolysis but using grid electricity, (iii) grey hydrogen, produced from natural gas using steam reforming and (iv) blue hydrogen, which is similar to grey hydrogen, but uses hot potassium carbonate as the solvent for carbon capture and storage. The paper considers the production of hydrogen necessary for 2 trips per day of a medium size ferryboat to navigate full electric for 7 h in the Adriatic Sea. Process simulation is applied to solve material and energy balances for each process investigated, as well as for the evaluation of capital and operating costs. Process simulation outcomes are then used to estimate three key performance indicators focused on energetic, economic, and environmental sustainability issues: the energy return on energy invested, the levelized cost of hydrogen, and the life cycle assessment. The energy indicator for grid and green hydrogen has a value of 13.39–14.29, versus a value of 4.59–5.48 for other hydrogen production methods from natural gas. The cost for green hydrogen is slightly higher (8.76) compared to the blue hydrogen (5.50) however green hydrogen has a much lower impact to the environment. Considering the combined results obtained by all the indicators, it is concluded that the most sustainable hydrogen production method is green hydrogen. • Process simulation provides data to design hydrogen production processes. • Green hydrogen has larger return of energy invested than natural gas-based routes. • Floating photovoltaic production is competitive for green hydrogen production. • Life cycle assessment shows excellent results for green hydrogen. • Indicators are evaluated for hydrogen use in the maritime industry. [ABSTRACT FROM AUTHOR]

Hydrogen is expected to be a game changer in the fight against climate change, being able to support the clean energy transition through a variety of roles: decarbonizing different hard-to-abate industrial sectors (such as steel, cement production) and transport (in long haul vehicles, maritime transport, and aviation), direct use as a fuel, chemical feedstock or in the form of synthetic fuels, and providing the ability to integrate with hybrid energy systems and renewables, enhancing energy storage and tapping the full potential of renewable energy sources. As a consequence, a substantial expansion in hydrogen production, due to rise in the demand, is expected by 2050, with all the generation coming from zero-carbon processes (electrolysis/thermochemical cycles using clean electricity and heat) or from a low-carbon production process using steam methane reforming with carbon capture and storage. Nuclear energy can be capitalized on both electricity and heat to provide a clean and reliable source of hydrogen through various processes. There are currently various demonstration projects undergoing in several countries to showcase the use of nuclear energy to produce clean hydrogen, considering both the current reactor fleet and advanced reactors. This paper provides an overview of these projects, giving an insight on the potential use of nuclear energy for hydrogen production and the current status of existing projects. It also highlights the activities of the International Atomic Energy Agency on technical and economic assessment of hydrogen production using nuclear energy for near term deployment. • Hydrogen is anticipated to be a game-changer in the fight against climate change. • Nuclear energy is positioned favourably to serve the developing hydrogen economy. • A single 1000 MW nuclear reactor could produce more than 200,000 t of H2 per year. • Several countries are considering nuclear hydrogen demonstration projects. • The IAEA has multiple resources available for nuclear hydrogen production. [ABSTRACT FROM AUTHOR]

Post-combustion carbon dioxide (CO 2) capture via flue gas is an advanced technology for mitigating greenhouse gas emissions. Its significance lies in the potential for retrofitting this technology to the current inventory of coal-fired power plants. This review paper aims to present the state of art in the technologies of adsorption techniques in post-combustion technologies to capture CO 2 from flue gas streams. These techniques have demonstrated numerous potential benefits when compared to conventional CO 2 capture methods that utilize aqueous amine solvents. Additionally, this overview presents the development in the field of novel solid sorbents for post-combustion CO 2 capture, focusing on their enhanced performance and favorable economic feasibility. The promising potential of mesoporous silica has been recognized to evaluate the enhanced capacity of CO 2 adsorption offered by these materials. Several research studies have reported different techniques of functionalizing porous silica by introducing amine groups. Various methods of functionalization for mesoporous silica, such as impregnation, grafting, and hybrid approaches, have been examined to improve the efficiency of the sorbents. Furthermore, this work summarises the research challenges with porous silica materials and indicates the possibilities for future studies to improve post-combustion carbon. [ABSTRACT FROM AUTHOR]

Oilfield wastewater with high moisture content can be efficiently treated by supercritical water gasification (SCWG) technology to produce hydrogen. This paper conducted a thermodynamic and environmental analysis of the oilfield wastewater SCWG system to provide optimization strategies. The waste heat utilization technology can enhance the heat integration of the system to reduce the exergy destruction and increase the H 2 yield. Sensitivity analysis showed that a ratio of preheating water to emulsion 3 can promote water-sensitive reactions to produce H 2 and save the H 2 needed to maintain the energetically self-sufficient system. Low system pressures, high feedstock preheating temperatures, and low oxidation reactor temperatures can reduce system energy destruction to obtain high H 2 yield and system efficiency. Meantime, the developed SCWG system has the potential to achieve natural enrichment of greenhouse gases after the H 2 separation has been completed. The use of waste heat utilization technology and carbon capture and storage (CCS) technology is expected to increase system efficiency to 53.43 % and reduce global warming potential (GWP) of 5.52 kg CO 2 -eq/kg H 2. This work would be of great value to the process design and optimization for the SCWG system of oilfield wastewater. [Display omitted] • The process of supercritical water gasification of oilfield wastewater was simulated. • Optimization strategies were given by thermodynamic and environmental analysis. • Operational details were revealed by comprehensive sensitivity analysis. • The exergy efficiency of 53.43 % were obtained. • Global Warming Potential decreased to 5.52 kg CO 2 -eq/kg H 2 with CCS. [ABSTRACT FROM AUTHOR]

This study investigates the potential of natural gas-based plants designed to produce blue hydrogen and decarbonized electric power, conceived to operate flexibly depending on the electricity price. This paper considers plants based on fired-tubular reforming (FTR) and auto-thermal reforming (ATR) technologies, with MDEA-based pre-combustion CO 2 capture process and partial electrification of the reformer, designed to achieve CO 2 capture efficiency higher than 95 %. Heat and mass balances for the chemical and power island are evaluated at both full and part load to define the corresponding operating maps. With pre-combustion CO 2 capture only, FTR plants can achieve CO 2 capture rates higher than 90 %, H 2 production efficiency of 73–74 % and power generation efficiency of around 47 %. Reformer electrification allows increasing overall capture efficiency to 95 %. Plants based on ATR can approach 95 % capture efficiency without electrification and achieve H 2 efficiency similar to FTR but higher electric efficiency, close to 51 %. An economic analysis is performed to assess profitability of the plants under electricity price scenarios with different penetration of renewables. The economic analysis shows that flexible plants may be profitable in future scenarios with high penetration of renewables and high price variance, resulting in IRR around 10–17 % for hydrogen selling prices of 2.0–2.5 €/kg, natural gas price of 9 €/GJ and carbon tax of 100 €/t CO2. [Display omitted] • Techno-economic study of low-emission H 2 & power plants with CO 2 capture. • Fired tubular reformers and autothermal reformers compared. • Reformer electrification increases capture rate and gives operational flexibility. • 71.3–75.2 % hydrogen production efficiency and 47.4–50.9 % electric efficiency estimated. • IRR 10–17 % in future high wind electricity market with hydrogen prices of 2.0–2.5 €/kg. [ABSTRACT FROM AUTHOR]

Direct air capture of carbon dioxide (CO 2) is technically a feasible solution for reducing atmospheric CO 2 concentrations at scale, building on decades of global research. However, powering such systems even partially with CO 2 -intensive fossil fuels results in more CO 2 emissions. This paper presents a novel energy management strategy (EMS) to further explore modular offshore wind energy off Canada's West Coast via power-to-direct air capture and power-to-gas systems. The system architecture includes a 15 MW wind turbine paired with a hydrogen energy storage system, i.e. hydrogen production and storage, and direct air capture (DAC) units. Hydrogen production from wind generation is stored and used to offer two key benefits: to deliver the thermal loads of the DAC system, and to meet hydrogen demand for external consumers. The proposed EMS offers an extra degree of freedom to operate the designed system by setting the priority either to maximize the amount of CO 2 capture or to maximize the amount of H 2 production for external consumers. In particular, the study incorporates dynamic mathematical modeling and constraints formulation for the aforementioned scenarios; DAC priority for CO 2 capture and H 2 for external hydrogen demand satisfaction. The effectiveness of the proposed EMS is shown through extensive simulations with different seasonal conditions. • Detailed mathematical dynamical models for offshore power-to-DAC and power-to-gas systems. • Green hydrogen production for two-fold benefits; H 2 for meeting DAC thermal loads, and H 2 as fuel for external consumers. • Scenario 1 prioritize the CO 2 capture rate, while scenario 2 maximizes the H 2 production for external consumers. • Design of EMS shows the correct unit commitment of the CO 2 capture rate and H 2 tracking. [ABSTRACT FROM AUTHOR]

In order to reverse the trend of increasing carbon dioxide (CO 2) emissions, the development of efficient and economical CO 2 trapping agents is an urgent necessity for the sustainable development of industry. In this paper, hierarchical porous hydroxyl aluminum oxide (AlOOH) hollow microspheres with controllable structure and morphology were prepared by conventional hydrothermal synthesis using malonic acid as a structure guiding agent. Then, potassium carbonate (K 2 CO 3) based adsorbents were prepared using AlOOH hollow microspheres as supports, and their CO 2 trapping performance was assessed by simulating industrial flue gas flow in a fixed bed. The results show that the loading of K 2 CO 3 , the pore structure, and the surface basic site of the adsorbent have a significant influence on the trapping performance of CO 2. Among the prepared K 2 CO 3 /AlOOH adsorbents, 30 wt% K 2 CO 3 /AlOOH adsorbent has the best CO 2 capture ability, which is about 2.15 times higher than that of K 2 CO 3 /C–Al 2 O 3 adsorbent prepared from commercial alumina (C–Al 2 O 3). There may be two explanations for this. Firstly, it may be due to the nanostructured shell and hierarchical porous structure of the adsorbent, which reduces the intra-particle diffusion resistance of CO 2 , and secondly, it may be due to the suitable surface basic sites of the adsorbent. In addition, the adsorbent was regenerated at 120 °C after trapping CO 2 , and then CO 2 was captured in a cycle. It was found that the CO 2 capture capability of the adsorbent did not decrease significantly after 10 cycles. In this work, an excellent technique for preparing porous honeycomb adsorbents with suitable surface basic sites has been devised, which provides a creative strategy for capturing and utilizing CO 2. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, we present a novel variant of the Covering Tour Problem (CTP), called the Covering Tour Problem with Varying Coverage (CTP-VC). We consider a simple graph G = (V , E) , with a measure of importance assigned to each node in V. A vehicle with limited battery capacity visits the nodes of the graph and has the ability to stay in each node for a certain period of time, which determines the coverage radius at the node. We refer to this feature as stay-dependent varying coverage or, in short, varying coverage. The objective is to maximize a scalarization of the weighted coverage of the nodes and the negation of the cost of moving and staying at the nodes. This problem arises in the monitoring of marine environments, where pollutants can be measured at locations far from the source due to ocean currents. To solve the CTP-VC, we propose a mathematical formulation and a heuristic approach, given that the problem is NP-hard. Depending on the availability of solutions yielded by an exact solver, we evaluate our heuristic approach against the exact solver or a constructive heuristic on various instance sets and show how varying coverage improves performance. Additionally, we use an offshore CO 2 storage site in the Gulf of Mexico as a case study to demonstrate the problem's applicability. Our results demonstrate that the proposed heuristic approach is an efficient and practical solution to the problem of stay-dependent varying coverage. We conduct numerous experiments and provide managerial insights. • Stay-dependent coverage in Covering Tour Problem improves the efficiency. • Time spent in a node influences the area of coverage or covering set. • Adaptive metaheuristic algorithm tackles the increased complexity. • The problem is applied to environmental monitoring of offshore Carbon Capture and Storage site. [ABSTRACT FROM AUTHOR]

• Step-by-step procedure to develop the tabulation and map component of UIC class VI permit. • Qualitative risk assessment methodology for all types of wells within AoR penetrating the confining zones. • Highlights the need for crossflow modelling of CO 2 leakage through improperly plugged wells. • Generalized categorization of legacy wells based on geologic penetrations and protections. Carbon Capture & Storage (CCS) refers to capturing the anthropogenic carbon dioxide (CO 2) at a source followed by injecting and storing it safely in the subsurface. The success of the CCS projects therefore heavily relies on how efficiently the confining zones (containment seals) prevent migration of the CO 2 to the surface and/or to the underground sources of drinking water (USDW) through leakage pathways. CCS projects requires drilling of Underground Injection Control (UIC) Class VI wells for permanent storage of CO 2 in subsurface. Detailed information of all the wells within the Area of Review (AoR) is needed to develop the map and tabulation components of the Class VI well permit application. This paper discusses the generic process that can be used by permit applicants to develop the dataset necessary for preparing the map and tabulation components of the Class VI permit application and perform qualitative risk assessment of all the wells within the AoR. This methodology directs the corrective action plans as well as monitoring plans to some extent. Results of the application of the newly developed methodology for wells in Illinois basin is discussed in detail. This methodology can be applied to all wells including orphaned wells, abandoned wells, active oil and gas wells, stratigraphic wells, disposal wells, etc. This methodology generalized categorization of legacy wells that will help in easier comparison of different CCS projects across the globe. The qualitative risk assessment methodology discussed in this paper is a good starting point for developing crossflow modeling. [ABSTRACT FROM AUTHOR]

Efficient treatment of antibiotic residue, containing a range of persistent organic compounds, is essential to ensure the protection of both the environment and human health. Supercritical water gasification technology could achieve the clean and efficient energy conversion of antibiotic residues. In this paper, a self-thermal supercritical water gasification system for antibiotic residues is developed to convert antibiotic residues to high-purity H 2 and electrical power. The system analysis results demonstrate that increasing the antibiotic residue slurry concentration, elevating the gasification reactor temperature, and optimizing the ratio of water-to-dry antibiotic residues effectively enhance system efficiency and H 2 yield within specific ranges. The H 2 yield and net electrical power at optimal operating conditions are 634.52 kg/h and 2.3 MW with 10 t/h dry antibiotic residue feeding. Meanwhile, the energy efficiency, exergy efficiency, and cold gas efficiency of the system are 61.32%, 63.05%, and 53.96%, respectively. The life cycle assessment analysis shows that the global warming potential of the system is 20.77 kg CO 2 -eq/kg H 2 with the above operating conditions. Taking into account the emission reduction impact of the system on thermal power generation, the inclusion of CO 2 capture and storage units can potentially lead to a negative global warming potential for the system. [ABSTRACT FROM AUTHOR]

Carbon Capture and Storage (CCS) involves transportation of liquefied CO 2 from capture sites to permanent storage locations, which is usually achieved by pipeline transportation or maritime shipping. Over long distances, maritime shipping at pressures around 16 bara has proved to be a more effective solution than transportation through pipelines. These conditions, although safe, offer a significant pressure margin with respect to the triple point of CO2 for more cost-effective ship design with larger transportation capacity. However, the reliability of this technology has not been fully demonstrated regarding depressurization operations commonly performed to minimize hazards associated to emergencies. For CO2, this operation entails risks such as dry ice formation. This paper focuses on two purposes. First, it reports detailed and extensive experimental tests of CO2 depressurization of a tanks at low pressure (< 20 bara). An extensive review of public domain literature showed that this data is scarce [20] This work focuses on contributing to close that gap. Finally, this work will present detailed simulations of the experiments using commercial flowsheeters to assess the reliability of standards models that are commonly used for engineering studies and design. All the experimental work was carried out using a bench scale tank of 2 m3 with ample instrumentation according to an experimental design. The results of the runs were modelled using the EO-Blowdown utility implemented in UniSim Design®. The results showed that modelling of CO2 systems with the EO-Blowdown utility is reliable and can reproduce accurately most key process variables, although it has some limitations such inability to model solid phases and metastable liquids [Display omitted] [ABSTRACT FROM AUTHOR]

This two-part paper investigates the feasibility of producing export quantities (770 t/d) of blue hydrogen meeting international standards, by gasification of Victorian lignite plus carbon capture and storage (CCS). The study involves a detailed Aspen Plus simulation analysis of the entire production process, taking into account fugitive methane emissions during lignite mining. Part 1 focusses on the resources, energy requirements and greenhouse gas emissions associated with production of gaseous and liquefied hydrogen, while Part 2 focusses on production of ammonia as a hydrogen carrier. In this study, the proposed process comprises lignite mining, lignite drying and milling, air separation unit (ASU), dry-feed entrained flow gasification, gas cooling and cleaning, sour water-gas shift reaction, acid gas removal, pressure swing adsorption (PSA) for hydrogen purification, elemental sulphur recovery, CO 2 compression for transport and injection, hydrogen liquefaction, steam and gas turbines to generate all process power, plus an optional post-combustion CO 2 capture step. High grade waste heat is utilised for process heat and power generation. Three alternative process scenarios are investigated as options to reduce resource utilisation and greenhouse gas emissions: replacing the gas turbine with renewable energy from off-site wind turbines, and co-gasification of lignite with either biomass or biochar. In each case, the specific net greenhouse gas intensity is estimated and compared to the EU Taxonomy specification for sustainable hydrogen. This is the first time that a coal-to-hydrogen study has quantified the greenhouse gas emissions across the entire production chain, including upstream fugitive methane emissions. It is found that both gaseous and liquefied hydrogen can be produced from Victorian lignite, along with all necessary electricity, with specific emissions intensity (SEI) of 2.70 kg CO 2 -e/kg H 2 and 2.73 kg CO 2 -e/kg H 2 , respectively. These values conform to the EU Taxonomy limit of 3.0 kg CO 2 -e/kg H 2. This result is achieved using a Selexol™ plant for CO 2 capture, operating at 89.5%–91.7% overall capture efficiency. Importantly, the very low fugitive methane emissions associated with Victorian lignite mining is crucial to the low SEI of the process, making this is a critical advantage over the alternative natural gas or black coal processes. This study shows that there are technical options available to further reduce the SEI to meet tightening emissions targets. An additional post-combustion MDEA CO 2 capture unit can be added to increase the capture efficiency to 99.0%–99.2% and reduce the SEI to 0.3 kg CO 2 -e/kg H 2. Emissions intensity can be further reduced by utilising renewable energy rather than co-production of electricity on site. Net zero emissions can then be achieved by co-gasification with ≤1.4 dry wt.% biomass, while a higher proportion of biomass would achieve net-negative emissions. Thus, options exist for production of blue hydrogen from Victorian lignite consistent with a 'net zero by 2050' target. Production of blue hydrogen from Victorian lignite. [Display omitted] • A detailed model for net-zero emissions hydrogen from Victorian lignite proposed. • Gasification of lignite, production of hydrogen and electricity, with CCS included. • Fugitive methane emissions during mining included in the model. • Options exist for greenhouse gas emissions to be consistent with 'Net zero by 2050'. • Production of low-emissions blue hydrogen from Victorian lignite is feasible. [ABSTRACT FROM AUTHOR]

Renewable power-to-fuel (PtF) is a key technology for the transition towards fossil-free energy systems. The production of carbon neutral synthetic fuels is primarily driven by the need to decouple the energy sector from fossil fuels dependance which are the main source of environmental issues. Hydrogen (H 2) produced from water electrolysis powered by renewable electricity and direct carbon dioxide (CO 2) captured from the flue gas generated by power plants, industry, transportation, and biogas production from anaerobic digestion, are used to convert electricity into carbon-neutral synthetic fuels. These fuels function as effective energy carriers that can be stored, transported, and used in other energy sectors (transport and industry). In addition, the PtF concept is an energy transformation that is capable of providing services for the balancing of the electricity grid thanks to its adaptable operation and long-term storage capacities for renewable energy surplus. As a consequence, it helps to potentially decarbonize the energy sector by reducing the carbon footprint and GHG emissions. This paper gives an overview on recent advances of renewable PtF technology for the e-production of three main hydrogen-based synthetic fuels that could substitute fossil fuels such as power-to-methane (PtCH 4), power-to-methanol (PtCH 3 OH) and power-to-ammonia (PtNH 3). The first objective is to thoroughly define in a clear manner the framework which includes the PtF technologies. Attention is given to green H 2 production by water electrolysis, carbon capture & storage (CCS), CO 2 hydrogenation, Sabatier, and Haber Bosch processes. The second objective is to gather and classify some existing projects which deal with this technology depending on the e-fuel produced (energy input, conversion process, efficiency, fuel produced, and application). Furthermore, the challenges and future prospects of achieving sustainable large-scale PtF applications are discussed. • An overview on recent advances of renewable power to fuel technologies. • Power-to-methane (PtCH4), power-to-methanol (PtCH3OH) and power-to-ammonia (PtNH3). • Green hydrogen production, carbon capture and storage, and CO 2 hydrogenation. • Energy input, conversion process, efficiency, fuel produced, and application. • Role of power to fuel technologies for the decarbonization of energy sector. [ABSTRACT FROM AUTHOR]

The core of the energy transformation under the carbon-neutral vision is the gradual replacement of high-carbon energy by zero-carbon and low-carbon energy. However, the large-scale deployment of clean energy technology in turn relies on key minerals such as copper, aluminum, zinc, and nickel. Based on this, this paper conducts research on the demand for key minerals in clean energy transition and the role of key minerals in clean energy transition. In particular, this paper calculated the demand for mineral supply for China's carbon neutrality target, and the impact of some mineral resource constraints on the carbon neutrality path. Relevant results can provide a decision-making basis for the future development and utilization of key mineral resources, as well as the implementation of future carbon-neutral goals. • We evaluate the impact of crucial mineral resource on the carbon neutrality path. • Copper's availability greatly affects the adoption of new energy technologies. • Limited resources hinder early carbon capture and storage development. • Negative emission technologies are necessary for China's carbon neutrality. [ABSTRACT FROM AUTHOR]

Biomass direct-fired power plant integrated with carbon capture system can achieve negative CO 2 emission during the power generation, which provides an important technology pathway for the transformation of energy system towards carbon neutrality. Understanding the economic competitiveness and CO 2 reduction potential of the plant, and identifying the optimal operating mode are the key to fully exert the advantages of the technology. For this reason, this paper develops life cycle economic and CO 2 emission assessment models for the biomass direct-fired circulating fluidized bed boiler power plant (BCFBP) integrated with solvent-based post-combustion carbon capture (PCC) system. The levelized cost and CO 2 emission of energy indexes are then applied to evaluate the performance of the BCFBP-PCC system. Based on the life cycle assessment, a novel economy and CO 2 reduction dual-objective operating optimization approach is proposed for the BCFBP-PCC to find the optimal hourly power generation and CO 2 capture level of the plant under given market conditions. The static investment payback period is employed as a constraint in the optimization to narrow down the range of the solution set and provide clearer guidance for system operation. This paper provides the first work pioneered the economic and negative carbon operation optimization of the BCFBP-PCC system. [ABSTRACT FROM AUTHOR]

Chemical Looping Combustion (CLC) is a carbon capture technology that uses an oxygen carrier to transfer the oxidizing agent to the fuel for combustion. This study used different machine learning algorithms, Artificial neural network and Response surface methodology to estimate the surface region process performance and optimize the process condition for the CLC of different solid fuels waste paper, plastic waste, and sugarcane bagasse blends. Based on the combustion efficiency, CO 2 yield and CO 2 capture efficiency responses, A high performance correlation (R2 > 0.8) was obtained for all the combustion parameters analyzed. The perturbation plot derived from the RSM analysis indicated that the most significant input parameters include the steam to fixed carbon, blend ratio and the fuel reaction temperature. The CLC process was optimized using RSM. For blends of SCB/WP, the best operating conditions were found to be 800 °C, a solid flow rate of 197.7 kg/h, an oxygen carrier to fuel ratio of 1.1, a steam to fixed carbon ratio of 2.16, and a blend ratio of 1. Similarly, for blends of SCB/PW, the optimal operating conditions were 800 °C, a solid flow rate of 199.4 kg/h, an oxygen carrier to fuel ratio of 1.3, steam to fixed carbon ratio of 2, and a blend ratio of 0.3. The optimum combustion performance was found to be 0.98, 0.78, and 0.96 for SCB/WP and 0.99, 0.62, and 0.96 for SCB/PW, respectively. • The process performance of the CLC of MSW/biomass blend was compared using ANN and RSM. • The optimal blend ratios for SCB/WP and SCB/PW blends were 1 (25% WP) and 0.3 (42.5% PW). • The combustion performance of the WP improved by 6.2% and 3.5% in terms of combustion efficiency and CO 2 yield, respectively. • The most significant input factors were discovered to be the blend of fuels ratio and the steam to fixed carbon ratio. [ABSTRACT FROM AUTHOR]

In recent years, there has been a notable surge in focus on the mitigation of carbon emissions, mostly motivated by the urgent concern about global warming and its adverse impacts on the Earth's climate. Power-to-gas (PtG) systems have emerged as a promising technological solution in the pursuit of mitigating carbon emissions. This paper presents a mathematical modeling framework that aims to accurately represent the power-to-gas system integrated with wind power plants while taking into account the technological constraints of the system in practical scenarios. To analyze the proposed system under the stresses, worst situations caused by existing uncertain parameters, especially wind power, is modeled using a risk modeling technique called downside risk constraints (DRC). The DRC endeavors to mitigate the likelihood of situations resulting in significant stresses by incorporating an expected downside risk into the proposed framework. This paper will provide a number of conservative tactics to be employed in the decision-making process under the realizations of uncertainties. These tactics, including strategic operational control strategies, provide a structured approach for decision-making under uncertain conditions. By incorporating downside risk constraints, the framework enables conservative decision-making that prioritizes mitigating potential losses and minimizing the operational risk within scheduling horizon of proposed PtG facility. The findings demonstrate that the implementation of PtG technology has the potential to yield a substantial reduction in external energy consumption, namely by 39.1 %. Additionally, it has been seen that PtG may effectively mitigate carbon emissions, resulting in a decrease of 38.9 %. The utilization of PtG technology and gas storage will result in a substantial reduction in wind curtailment, ultimately leading to a near elimination of curtailment. Further study is conducted on the model in order to explore the benefits of carbon and methane storage, as supported by the results obtained. [ABSTRACT FROM AUTHOR]

With the increasing severity of global warming, the goal of carbon sequestration and emission reduction in various industries has become an important responsibility for sustainable development. As an important part of carbon sink, the improvement of net carbon efficiency in the plantations industry will make a great contribution to the realization of the "double carbon" target in agriculture. However, there are large spatial and temporal differences in the net carbon efficiency of the plantations sector in various provinces, and there is still a large scope for increasing carbon sink and reducing carbon emission. In this paper, we have analyzed spatial and temporal trends in the net carbon sink efficiency of the plantations' production processes in 31 provinces in China (excluding Hong Kong, Macao and Taiwan) from 2000 to 2020. On this basis, we have analyzed the influencing factors of net carbon efficiency in the plantations' production process through an extended Kaya constant equation. Through the geographically and temporally weighted regression model, we explore the spatio-temporal heterogeneity of the influencing factors, and further analyze the driving and restraining factors of net carbon efficiency in plantations' production process, in order to propose appropriate countermeasures. The study shows that: (1) The net carbon efficiency of plantations sector in China increase between 2000 and 2020, and the development of net carbon efficiency is uneven across regions. (2) The geographic center of net carbon efficiency of China's plantations industry shift from the northeast to the southwest and is consistent with the migration direction of agricultural inputs. (3) The influencing factors of net carbon efficiency in the plantations sector show large regional differences, and can be specifically divided into four major types of zones. In this regard, this paper provides more appropriate countermeasure suggestions for increasing carbon sink and reducing carbon emission in each zone, with a view to achieving the goal of double carbon in agriculture with practical significance. • Net carbon efficiency is a new objective indicator to measure the carbon sink level of cropland. • Cultivated land carbon sink capacity is closely related to agricultural inputs. • Regional differences in the factors influencing net carbon efficiency. [ABSTRACT FROM AUTHOR]

Steam methane reforming (SMR) needs the reaction heat at a temperature above 800 °C provided by the combustion of natural gas and suffers from adverse environmental impact and the hydrogen separated from other chemicals needs extra energy penalty. In order to avoid the expensive cost and high power consumption caused by capturing CO 2 after combustion in SMR, natural gas Chemical Looping Reforming (CLR) is proposed, where the chemical looping combustion of metal oxides replaced the direct combustion of NG to convert natural gas to hydrogen and carbon dioxide. Although CO 2 can be separated with less energy penalty when combustion, CLR still require higher temperature heat for the hydrogen production and cause the poor sintering of oxygen carriers (OC). Here, we report a high-rate hydrogen production and low-energy penalty of strategy by natural gas chemical-looping process with both metallic oxide reduction and metal oxidation coupled with steam. Fe 3 O 4 is employed as an oxygen carrier. Different from the common chemical looping reforming, the double side reactions of both the reduction and oxidization enable to provide the hydrogen in the range of 500–600 °C under the atmospheric pressure. Furthermore, the CO 2 is absorbed and captured with reduction reaction simultaneously. Through the thermodynamic analysis and irreversibility analysis of hydrogen production by natural gas via chemical looping reforming at atmospheric pressure, we provide a possibility of hydrogen production from methane at moderate temperature. The reported results in this paper should be viewed as optimistic due to several idealized assumptions: Considering that the chemical looping reaction is carried out at the equilibrium temperature of 500 °C, and complete CO 2 capture can be achieved. It is assumed that the unreacted methane and hydrogen are completely separated by physical adsorption. This paper may have the potential of saving the natural gas consumption required to produce 1 m3 H 2 and reducing the cost of hydrogen production. • A mid-temperature chemical looping reforming hydrogen production method via natural gas was proposed. • We provide a possibility of methane hydrogen production from more than 800 °C to about 500 °C under atmospheric pressure. • This paper may have the potential of saving the natural gas consumption and reducing the cost of hydrogen production. • It would be combined with medium-temperature industrial waste heat or parabolic trough concentrating solar energy. [ABSTRACT FROM AUTHOR]

Blue carbon, a concept that emerged in the last decade, has received increasing attention in recent years. The development of blue carbon as a nature-based solution is crucial to global climate governance, biodiversity conservation, and restoration of fishery resources. This study utilized CiteSpace visualization software to conduct bibliometric and systematic analyses of 3474 papers retrieved from the Web of Science Core Collection in 2003–2022, depicting a comprehensive framework of international research on blue carbon, exploring hotspots and trends, and proposing future directions and implications for ocean and coastal management. Overall, blue carbon research has experienced the early exploration period (2003–2007) based on scientific concepts, the development period (2008–2015) of research on carbon sequestration mechanisms and functions of different organisms and ecosystems, and the outbreak period (2016–2022) of carbon sink system quantification and management based on model prediction. Co-authorship analysis indicated that blue carbon research collaborates well across intuitions and countries, while collaboration among authors needs to be strengthened. Thematic evolution and hotspot analysis based on cited references and keywords revealed that coastal wetlands, especially mangroves, are a popular research theme, and the functional protection and development of management strategies for coastal ecosystems are major current research hotspots. In addition, it emphasized the need to focus on the protection, restoration and creation of blue carbon ecosystems (BCEs), develop sustainable marine ranching to promote blue carbon trading, explore more potential emerging blue carbon, and strengthen the management of blue carbon from the social level in the future. This paper combines traditional bibliometric review with modern visual analysis software to carry out network metrics, clustering and visualization of the blue carbon thematic literature from multiple perspectives, which reflects its novelty. It provides the latest, in-depth and comprehensive insights into blue carbon research that will serve as valuable reference for relevant scholars, managers and governments. [Display omitted] • Blue carbon field has experienced exploration, development and outbreak periods. • Blue carbon research is well-collaborated across institutions and countries. • Coastal wetlands, especially mangroves, have been a popular central research area. • Protection and management of coastal ecosystems are new hotspots in research. • Propose ocean and coastal management implications for realizing the potential of blue carbon. [ABSTRACT FROM AUTHOR]

• Carbon dioxide capture and mitigation are key to the technological response to combat climate change and reduce CO 2 emissions. • Proposal of a novel system for performance improvement of the conventional post-combustion process. • Thermodynamic, economic, and environmental analyses of the proposed cycles. • The desorption column has the largest contribution to the exergy destruction 257.48 k W. • The solvent regeneration energy decreases to 2.77 G J / t C O 2 , 20.17 % lower compared to the conventional system. An optimum process with a novel method for improving the thermodynamic efficiency of the conventional post-combustion process based on a mono-ethanolamine (MEA) 30 wt% solvent is presented. The presented process, by preheating the rich solvent stream twice and using lean vapor compression (LVC), causes the solvent regeneration energy (E regen) to decrease, the exergy efficiency of the desorption column to increase, and the net CO 2 emission to diminish. According to the simulation results, the solvent regeneration energy in the base process is 3.47 GJ/t CO2 and has a value of 2.77 GJ/t CO2 in the proposed scheme, which exhibits a 20.17% decrease. The exergy analysis showed that the desorption column contributes the most to the exergy destruction in the post-combustion process. According to the performed analysis, in the proposed scheme, the exergy destruction in the desorption column reduces from 476.67 kW to 257.48 kW, which shows a 45.98% decrease. Under these conditions, the exergy efficiency of the desorption column is improved by 12.2%. Comparing E r e g e n parameter with that of previous studies demonstrated that the proposed scheme in this paper has significant superiority regarding optimizing the reboiler's energy. Due to the addition of a compressor, heat exchanger, expansion valve, and separator, the annual capital expenditure (CAPEX y) of the proposed scheme is 13.71% higher than the conventional process, which results in a 12.5% increase in the cost of CO 2 capture ( C o s t C O 2 , c a p t u r e ). [ABSTRACT FROM AUTHOR]