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About one million tons of CO2 have been injected into the Farnsworth unit to date. The target reservoir for CO2 injection is the Morrow B Sandstone, which is primarily made of quartz with lesser amounts of albite, calcite, chlorite, and clay minerals. The impact of CO2 injection on the mineralogy, porosity, and pore water composition of the Morrow B Sandstone is a major concern. Although numerical modeling studies suggest that porosity changes will be minimal, significant alterations to mineralogy and pore water composition are expected. Given the implications for CO2 storage effectiveness and risk assessment, it is crucial to verify the accuracy of theoretical model predictions through laboratory experiments. To this end, batch reaction experiments were conducted to model conditions near an injection well in the Morrow B Sandstone and at locations further away, where the CO2 has been diluted by formation water. The laboratory experiments involved submerging thin sections of both coarse- and fine-grained facies of the Morrow B Sandstone in formation water samples with varying levels of CO2. The experiments were conducted at the reservoir temperature of 75 °C. Two experimental runs were conducted, one lasting for 61 days and the other for 72 days. The initial fluid composition used in the second run was the same as in the first. The mineralogy changes in the thin sections were analyzed using SEM and the Tescan Integrated Mineral Analyzer (TIMA), while changes in the composition of the formation water were determined using ICP-AES. During each experiment, a thin layer of white fine-grained particles consisting mainly of dolomite and silica formed on the surface of the thin sections, leading to significant reductions in Ca, Mg, and Sr in the formation water. This outcome is consistent with numerical model predictions that dolomite would be the primary mineral that would react with injected CO2 and that silica would be oversaturated in the formation water. Changes in mineral abundance in the thin sections themselves were much less systematic than in the theoretical modeling experiments, perhaps reflecting heterogeneities in the mineral grain size surface area to volume ratios and mineral distributions in the thin sections not considered in the numerical models.

Moving toward net zero emissions require new approaches and technologies, including capturing CO2 from industrial sources, especially in remote locations where currently using fossil fuels could be unavoidable for generating electricity or machinery for mining, production of cement, steel, hydrogen, gas processing, etc. Mineral carbonation could fix CO2 in a highly stable solid form. This study explores intensifying the carbonation process of natural Canadian silicates and minerals, kimberlite and wollastonite, which are available in mining sites where the emission occurs. Kimberlite is well-known for containing diamonds. After extracting the diamonds, the value of tailings can vary widely depending on the mineral content and the processing costs, while kimberlite is not as reactive as wollastonite for CO2 sequestration purposes. This study explored the effects of ball milling and various methods for intensifying the mineral carbonation process for CO2 sequestration. Calcium and magnesium hydroxides were used as reference materials to assess the effectiveness of the ball-mill reactor. Then, various parameters in the intensification of the carbonation process were investigated, and the effects of additives (sodium hydroxide and magnesium chloride), solvents (pure water and ethanol), and process parameters (temperature, reaction time, and CO2 level) on carbonation and reaction rate, CO2 uptake and mineral conversions were investigated. The carbonated samples were subjected to pH testing, calcimetry, XRD analysis and scanning electron microscopy (SEM). For most feedstocks, water as the main solvent led to higher carbonation and precipitating of different carbonates (hydromagnesite, aragonite, calcite, etc.), while for kimberlite, using NaOH led to higher performance. Ball-milling is designed for purposes such as milling, grinding, etc. The centrifugal forces and related phenomena could limit the contraction of CO2 and other materials in the ball mill jar. However, the results of this study suggest that ball-milling can assist in intensifying mineral carbonation reactions.

Major concerns of carbon dioxide (CO2) sequestration in subsurface formations are knowledge of the well injectivity and gas storage capacity of the formation, the CO2 pressure and saturation plume extensions during and after injection, and the risks associated with CO2 leakage and fault reactivation. Saline reservoirs are considered as one of the target formations for CO2 sequestration through structural, residual, dissolution, and mineral trapping mechanisms. The boundary condition of the saline reservoir dictates the pressure and saturation plume extension of the injected supercritical CO2 that could expand over large distances. This can lead to sources of risk, e.g., leakage and/or fault reactivation due to presence of wells, thief zones, and geological discontinuities. Therefore, there is a critical need to develop a model that describes how risk-related performance metrics (i.e., the CO2 saturation plume size, the pressure differential plume area, and the pressure differential at specific locations) vary as a function of the size of injection, time following injection, injection operations, and geologic environment. In this study, a systematic reservoir modeling studies of anthropogenic CO2 sequestration in Citronelle dome, Alabama, was performed where all relevant scenarios and conditions to address the questions of the saturation and pressure plume size in the area of review (AoR) and post-injection site care (PISC) are considered. The objective for this study was firstly to systematically simulate CO2 sequestration, i.e., saturation dynamics, and pressure behavior over a range of operational and geological conditions and to derive conclusions about the factors influencing saturation and pressure plume size, post-injection behavior, and the risk associated with them, by developing third-generation reduced order models (ROMs) for reservoir behavior. Finally, to assess the uncertainty associated with our studies, Latin Hypercube Sampling (LHS) together with an experimental design technique, i.e., Plackett–Burman design, was used. Application of Pareto charts and respond surfaces enabled us to determine the most important parameters impacting saturation and pressure plume sizes and to quantify the auto- and cross-correlation among different parameters in both history-matched and upscaled models.

Protection of the natural environment is one of the most significant global challenges for the international community. World problems arising as a result of the incineration of fossil fuels, excessive CO2 emissions, erosion and soil degradation, as well as air pollution with the accelerating greenhouse effect and changes to the climate condition, make it necessary to take action at many levels. Environmental protection and the protection of natural resources need to follow the principles of sustainable development. Looking for alternative energy sources is appropriate but not sufficient and should be conducted in various areas since natural environmental changes are accelerating with many consequences. Therefore, there is demand for implementation of applications aimed at protecting air, and soil, preventing waste formation and combating the greenhouse effect. Therefore, the multi-directional use of various biocarbon substances for activities related to renewable energy, land reclamation, and carbon dioxide capture from the atmosphere is a promising and significant direction. This paper presents multidirectional analysis related to the use of biocarbon obtained from biomass and MSW waste.

In order to reduce CO₂ emission, the CO₂ sequestration using particulate steelmaking slag in water is world widely being studied through a Ca-carbonation method. As consequence, the improved efficiency of Ca leaching from the steelmaking-slag particles contributes significantly to increasing the amount of fixed CO₂. Therefore, in this study, for the purpose of understanding the Ca leaching from steelmaking slag particles, the rate of Ca leaching in week acidic solution was analyzed by several leaching kinetics models such as the shrinking core model and the logarithmic rate law. In addition to Ca, the leaching rate of Fe which is one of the major elements was also investigated. The Ca and Fe leaching process with stirring could be fitted well by logarithmic rate law. Moreover, by the observation using SEM-EDX, it was observed that the residue after acetic acid leaching was porous material with the pores blocked. From these results, it was revealed that the mass transfer in the products blocking the pore surface of slag particles was very likely to be the rate-controlling step of Ca leaching. In fact, promoting mass transfer by ultrasonic irradiation could enhance the rate of Ca leaching remarkably. While the Ca leaching ratio reaches 56.6% at 300 min without ultrasonic irradiation, the leaching ratio reaches 57.3% just for 30 min leaching with ultrasonic irradiation. This study reveals that promoting the mass transfer in the products blocking the pore surface of slag particles is important for increasing the rate of Ca leaching.

Coal maceral composition has a great effect on gas adsorption and diffusion. The interaction between maceral composition and supercritical CO2 (SCCO2) fluid will affect gas diffusion behavior in coals. Thus, the diffusivity derived from adsorption kinetics of CH4 and CO2 in vitrinite- and inertinite-rich coals with low-violate bituminous rank collected from the Hancheng mine of the Weibei coalfield pre- and post-SCCO2 fluid exposure (SFE) were tested at the conditions of 45 °C and 0.9 MPa. In combination with pore distribution and functional group content, the possible mechanism of the alterations in gas diffusion characteristics in coals with various maceral compositions was addressed. The results show that for vitrinite-rich coals, SFE increases the macropore apparent diffusion coefficient of CH4, while this treatment decreases the micropore apparent diffusion coefficient of CH4. However, the reverse trend is found for CO2 diffusion–adsorption rate. For inertinite-rich coals post-SFE, CH4 diffusion–adsorption rate increases, while an increase and a decrease in diffusivity CO2 occur for macropore and micropore, respectively. Generally, SFE shows a stronger impact on CO2 adsorption rate than CH4 in coals. The results suggest that the diffusion of CH4 and CO2 in coals with different maceral compositions show selectivity to SCCO2 fluid. The possible reason can be attributed to the changes in pore structure and surface functional group content. SFE causes an increase in macro/mesopore volume of all samples. However, SFE induces a reduction in oxygen-containing species content and micropore volume of inertinite-rich coals, while the opposite trend occurs in vitrinite-rich coals. Thus, the changes in pore volume and surface functional group account for the difference in gas diffusivity of coals with different maceral compositions. With regard to the micropore diffusion–adsorption behavior of CH4 and CO2, the impact of oxygen-containing species is superior to pore volume. The oxygen-containing species favor CO2 diffusion–adsorption but go against CH4 transport. This effect accounts for the reduction in the micropore diffusion–adsorption rate of CH4 and the increase in micropore diffusivity of CO2 in vitrinite-rich coals, respectively. However, the aforementioned effect is the opposite for inertinite-rich coals. Overall, the changes in gas diffusion in coals with different maceral composition during the CO2-ECBM process requires further attention.

Microalgae cultivation can be used to increase the sustainability of carbon emitting processes, converting the CO2 from exhaust gases into fuels, food and chemicals. Many of the carbon emitting industries operate in a continuous manner, for periods that can span days or months, resulting in a continuous stream of gas emissions. Biogenic CO2 from industrial microbiological processes is one example, since in many cases it becomes unsustainable to stop these processes on a daily or weekly basis. To correctly sequester these emissions, microalgae systems must be operated under continuous constant conditions, requiring photobioreactors (PBRs) that can act as chemostats for long periods of time. However, in order to optimize culture parameters or study metabolic responses, bench-scale setups are necessary. Currently there is a lack of studies and design alternatives using chemostat, since most works focus on batch assays or semi-continuous cultures. Therefore, this work focused on the development of a continuous bench-scale PBR, which combines a retention vessel, a photocollector and a degasser, with an innovative recirculation system, that allows it to operate as an autotrophic chemostat, to study carbon sequestration from a biogenic CO2-rich constant air stream. To assess its applicability, the PBR was used to cultivate the green microalga Haematococcus pluvialis using as sole carbon source the CO2 produced by a coupled heterotrophic bacterial chemostat. An air stream containing ≈0.35 vol% of CO2, was fed to the system, and it was evaluated in terms of stability, carbon fixation and biomass productivity, for dilution rates ranging from 0.1 to 0.5 d−1. The PBR was able to operate under chemostat conditions for more than 100 days, producing a stable culture that generated proportional responses to the stimuli it was subjected to, attaining a maximum biomass productivity of 183 mg/L/d with a carbon fixation efficiency of ≈39% at 0.3 d−1. These results reinforce the effectiveness of the developed PBR system, making it suitable for laboratory-scale studies of continuous photoautotrophic microalgae cultivation. info:eu-repo/semantics/publishedVersion

The objective of the present study was to explore three types of vibro-compacted precast concrete mixtures replacing fine and coarse gravel with a recycled/mixed concrete aggregate (RCA or MCA). The portlandite phase found in RCA and MCA by XRD is a “potential” CO2 sink. CO2 curing improved the compressive strength in all the mixtures studied. One tonne of the mixtures studied could be decarbonised after only 7 days of curing 13,604, 36,077 and 24,635 m3 of air using natural aggregates, RCA or MCA, respectively. The compressive strength obtained, XRD, TGA/DTA and carbon emission evaluation showed that curing longer than 7 days in CO2 was pointless. The total CO2 emissions by a mixture using CO2 curing at 7 days were 221.26, 204.38 and 210.05 kg CO2 eq/m3 air using natural aggregates, RCA or MCA, respectively. The findings of this study provide a valuable contribution to carbon emission evaluation of CO2 curing in vibro-compacted precast concrete with recycled/mixed concrete aggregates (RCA or MCA). The technology proposed in this research facilitates carbon capture and use and guarantees enhanced compressive strength of the concrete samples.

To reduce the carbon footprint of cement and concrete industry, CO2 curing has been recognized as one of the sufficient ways. However, the amount of CO2 uptake by the normal structural concrete is limited because of their low permeability. Compared to curing the traditional concrete members, CO2 curing of pervious concrete is expected to sequester more CO2 due to the well-connected pore network and high permeability. In addition, studies on the effective utilization of resources found that the carbonation of recycled concrete aggregates (RCAs) prepared from the demolition building waste can improve the bonding between RCAs and the cement matrix. In this study, we propose to combine two carbonation steps (carbonation of RCAs and carbonation of precast pervious concrete) together to improve concrete quality and maximize CO2 sequestration in carbonated concrete. The preliminary experimental results show that the amount of CO2 captured by the carbonated pervious concrete with carbonated RCAs is higher than the normal concrete. Compared with non-carbonated RCAs, the strength of concrete with carbonated RCAs is improved. These results prove to a certain degree that the way of using the carbonation method to massively produce the precast pervious concrete is a feasible approach to mitigate carbon footprint of cement industry without scarifying the property of pervious concrete. ISSN:2211-0844

Koldioxidutsläpp (CO2) från energiproduktionsindustrin och transportsektorn globalt påverkar miljön negativt. Länder har enats om att minska utsläppen för att nå målet om en genomsnittlig temperaturökning på 1,5 °C till 2030. Trots detta förväntas de globala utsläppen av CO2 från fossila bränslen och industriella processer vara cirka 40 Gton per år fram till 2100. För att dra nytta av CO2-utsläppen och skapa värdefulla produkter med negativa utsläpp är mineralkarbonatisering en önskvärd process. Denna process innebär att CO2 och mineraler löses upp i en alkalisk lösning och bildar stabila produkter. Faktorer som partikelstorlek hos mineralerna och CO2-lösningshastigheten påverkar mineralkarbonatiseringens hastighet. Experiment utfördes med en batchreaktor från Paebbl AB och en matematisk modell utvecklades i Matlab. Resultaten jämfördes för olika partikelstorlekar i tre motståndsfall. Större partikelstorlek hos olivin visade sig öka tiden för total konvertering, oavsett motståndstyp. De modellerade motstånden beskrev inte tillräckligt processen och indikerade att alla tre motstånd har en samtidig och enhetlig effekt på olivinmineralisering, utöver eventuella begränsningar som föroreningar och biprodukter. Mineraliseringsexperiment med 20 μm partiklar under en timme gav 34,4% omvandling, medan 10 μm partiklar under två timmar gav 46,7% omvandling. En inledande undersökning av massöverföringsbegränsningar visade att CO2-lösningshastigheten inte är den begränsande faktorn, utan lägre omrörningshastigheter och beteendet hos (CO2 + olivin)-systemet behöver ytterligare studeras. Framtida forskning bör fokusera på att lösa dessa begränsningar. Carbon dioxide (CO2) emissions from the energy production industry and the transportation sector globally negatively affect the environment. A prominent example is the interconnection of carbon with the greenhouse effect. Countries have agreed to mitigate their emissions and try to fulfill the target of 1.5 oC average temperature increase by 2030, but in order to do so the global emissions of CO2 from fossil fuels and industrial processes will still lead up to the astonishing amount of 40 Gtons of CO2 each year until 2100. It is apparent that processes that try to take advantage of the emitted CO2 creating valuable products with negative emissions are highly desired. One of these is mineral carbonation, where CO2 and minerals dissolve in an alkaline solution and form stable products. Many factors affect the rate at which mineral carbonation happens. The effect of the particle size of the mineral in the process will be investigated, along the CO2 dissolution rate through the overall gas-liquid mass transfer coefficient (kLa), in order to get a better understanding of the process. Experiments were conducted with a batch reactor provided by Paebbl AB and a mathematical model was developed in Matlab. The experimental and numerical results, in regards to the particle size, were then compared for the cases of three resistances. This model can be developed further for use in a continuous mineralization process. The results revealed that increasing the particle size of olivine leads to a significant increase in the time required for total conversion, irrespective of the resistance type. The modelled resistances were found to inadequately describe the process, suggesting a simultaneous and uniform effect of all three resistances on olivine mineralization, in addition to the effect of other possible limitations such as impurities and by-products. Mineralization experiments with 20μm particles and a duration of 1 hour led to 34.4% conversion, whereas experiments with 10μm particles and a duration of 2 hours resulted in 46.7% conversion. Finally, the initial investigation of the mass transfer limitations in a system of CO2 and water led to an average kLa coefficient of 191 h-1, suggesting that the CO2 dissolution rate is not the limiting factor. However, the impact of lower stirring rates remains unexplored due to the absence of appropriate instrumentation and the behaviour of the (CO2 + olivine) system should also be studied. Future research should aim to address these limitations.

The gasification of Polish coal to produce hydrogen could help to make the country independent of oil and gas imports and assist in the rational energy transition from gray to green hydrogen. When taking strategic economic or legislative decisions, one should be guided not only by the level of CO2 emissions from the production process, but also by other environmental impact factors obtained from comprehensive environmental analyses. This paper presents an analysis of the life cycle of hydrogen by coal gasification and its application in a vehicle powered by FCEV cells. All the main stages of hydrogen fuel production by Shell technology, as well as hydrogen compression and transport to the distribution point, are included in the analyses. In total, two fuel production scenarios were considered: with and without sequestration of the carbon dioxide captured in the process. Life cycle analysis was performed according to the procedures and assumptions proposed in the FC-Hy Guide, Guidance Document for performing LCAs on Fuel Cells and H₂ Technologies by the CML baseline method. By applying the CO2 sequestration operation, the GHG emissions rate for the assumed functional unit can be reduced by approximately 44% from 34.8 kg CO2-eq to 19.5 kg CO2-eq, but this involves a concomitant increase in the acidification rate from 3.64·10−2 kg SO2-eq to 3.78·10−2 kg SO2-eq, in the eutrophication index from 5.18·10−2 kg PO3−4-eq to 5.57·10−2 kg PO3−4-eq and in the abiotic depletion index from 405 MJ to 414 MJ and from 1.54·10−5 kg Sbeq to 1.61·10−5 kg Sbeq.

The future emissions of carbon dioxide (CO2) are likely to increase beyond the current levels due to rapid industrialization in China. Several methods have been proposed as possible mitigation strategies to reduce the anthropogenically emitted CO2 from the atmosphere and water. This study provided the description of stratigraphic structure of the basin through analysis between the regional groundwater flow and the injection of carbon dioxide. The geological and geomechanical data was used to model the aquifer for geostatistical analysis. Data storage sites for geotechnical provided critical information to assess the potential risks and associated sequestration. The movement of groundwater occurred slowly with infiltration through the pores. CO2 was stored in deep aquifers for longer periods due to slow movement of water downstream. Over time, the injected CO2 dissolved water, forming minerals through chemical reactions, which converted it into carbonate minerals resulting in permanent sequestration.The chemistry of formation waters in this basin is important for many geological processes, such as the fluid-rock interaction, the migrating paths of fluid and the entrapment mechanisms of hydrocarbon. In this study, the emissions of CO2 were shifted several kilometers away from the storage area, such that the regional groundwater mixing affected the quality of surface water with consequent of toxicity to every living creature that depended on the available water from Urumqi River Basin. Injection of fluids into deep saline aquifers is therefore considered as the best mitigating strategy for CO2 abatement in water due to its enormous storage capacity.

Ugljikov dioksid, CO2, navodi se kao najznačajniji uzročnik učinka staklenika. Učinak staklenika povećava se proporcionalno s koncentracijom ugljikovog dioksida. Kako je koncentracija CO2 u atmosferi već odavno vrlo visoka, naš planet prolazi kroz globalno zagrijavanje koje se vrlo negativno odražava na klimu i uzrokuje katastrofalne štete. Neka od mogućih rješenja ovog gorućeg globalnog problema su smanjenje potrošnje energije, poticanje proizvodnje/potrošnje ekološki prihvatljivijih oblika energije, te ono jednako upečatljivo, a medijski podzastupljeno – sekvestracija CO2 iz atmosfere. Sekvestracija podrazumijeva dugoročno pohranjivanje CO2 u podzemlju, a može biti biotička i abiotička. Skladištenju CO2 prethodi hvatanje i pročišćavanje ili obrađivanje ukoliko je potrebno. Pojam sekvestracije sve se više spominje i u geoinženjerstvu. U geoinženjerstvo spada i tzv. DAC (engl. direct air capture) metoda. DAC metoda odnosi se na izravno prikupljanje CO2 iz zraka pomoću sorbensa. Prikupljeni CO2 može se skladištiti ili ponovno upotrijebiti. Na metodi izravnog hvatanja iz zraka temelji se i način djelovanja umjetnih drveća. Umjetna drveća su pasivni uređaji koji predstavljaju alternativu prirodnom drveću. Uz pomoć specifičnog sorbensa koji – kada je suh – ima visok afinitet za CO2, prikupljaju CO2 , a otpuštaju ga kada se sorbent smoči. Umjetno drveće ima svoje prednosti i nedostatke. Nedostaci su visoki troškovi, nepredvidivost i potreba za velikim prostorom. Prednosti su brzina prikupljanja CO2, mali utrošak energije i regenerirajući sorbent. U proteklih nekoliko godina, došlo je do razvoja tehnologija skladištenja CO2 te ovakvi projekti naoko imaju svijetlu budućnost, ali potrebna je veća potpora i educiranje šire zajednice., Carbon dioxide, CO2, is well known as the most significant contributor to the greenhouse effect. The greenhouse effect increases proportionally with the carbon dioxide concentration. As the concentration of CO2 in the atmosphere became very high, humanity is threatened by global warming, causing catastrophic damage due to more and more frequent extreme weather phenomena. Some of the possible solutions to this leading global concern are reducing energy consumption, encouraging the production/consumption of ecologically more acceptable energy sources, and just as important, but less media-prominent one: carbon sequestration. Carbon sequestration refers to the long-term storage of CO2 underground, either biotic or abiotic. CO2 storage is preceded by the capture and purification or processing if necessary. The concept of sequestration is being mentioned more and more in the realm of geoengineering. Geoengineering also includes the DAC (Direct Air Capture) method. The DAC method refers to the direct capture of carbon dioxide from the air using a sorbent. The captured CO2 can be stored or reused. The method of direct air capture is also the basis of artificial trees’ mechanism of action. Artificial trees are passive devices that represent an alternative to natural trees. With the help of a specific sorbent, which – when dry – demonstrates a high affinity for CO2, artificial trees collect CO2 and release it when the sorbent gets wet. Artificial trees have their advantages and disadvantages. Disadvantages are high costs, unpredictability, and a need for a large space area. The advantages are the speed of carbon collection, low energy consumption, and the possibility of sorbent regeneration. In the past few years, carbon dioxide storage technologies have been developed, and projects like this seem to have a bright future, but more support and education of a wider population are needed.

Public transport shelters provide an unused surface that can be utilized in various ways, including for unconventional landscaping. The benefits from greening of public transport shelters are insufficiently studied and unutilized. The article evaluates some of the benefits which may result from the construction of green public transport shelters in the central part of Sofia. There are a total of 2780 aboveground public transport stops in Sofia. In the surveyed area are located 257 stops, 150 of which currently have shelters. The potential of greened shelters to remove PM10 and CO2 from the ambient air is estimated for several different scenarios. If 250 public transport shelters are entirely greened (roof and 3 walls) with Festuca sp., the removed PM10 will be about 20 kg/yr, or 0.01% of the yearly emissions of PM10 from transport in the surveyed area. The sequestered CO2 will be 17047.3 kg /yr., or approximately the CO2 emitted by 40 diesel cars with an average daily mileage of 10 km per day for a year. The reduction of PM10 and CO2 is not significant, however, in a big city with intensive construction and a constantly increasing population, every possibility for greening needs to be explored. Green stops may be used in combination with other measures. Proper selection of plant species and design solutions maximizing the green surface will increase the benefits.

La importancia de los árboles para el ambiente se centra en los servicios que pueden ofrecer, siendo el de fijación de CO2 uno de los más destacados. El objetivo de la investigación fue estimar la cantidad de carbono capturado por el arbolado de las áreas verdes de la Universidad Laica Eloy Alfaro de Manabí. Para este propósito se realizó un inventario del estrato arbóreo. Se registraron todos los individuos con diámetro de 1.30 m (más menos 5 cm). Se evaluó la riqueza y abundancia, además de variables dendométricas (altura total, diámetro del tronco). Se calculó el carbono capturado a partir de la estimación de biomasa forestal. La densidad de la madera de las distintas especies se obtuvo de varias bases de datos forestales mundiales. Se identificaron 68 especies y 1200 individuos. La especie más abundante fue Azadirachta indica (37%). El secuestro de CO2 fue de 19 650.76 t. A pesar de que se fija una importante cantidad de carbono, muchos ejemplares se encuentran en conflicto con infraestructura física, lo cual requiere la remoción de estos. Se recomienda diseñar nuevas áreas verdes bajo estrictas normas de calidad, priorizando especies nativas., The importance of trees for the environment focuses on the services they can offer, CO2 fixation being one of the most prominent. The objective of the research was to estimate the amount of carbon captured by the trees in the green areas of the Universidad Laica Eloy Alfaro de Manabí. For this purpose, an inventory of the tree stratum was carried out. All individuals with a diameter at 1.30 m (plus minus 5 cm) were recorded. Richness and abundance were evaluated, as well as dendometric variables (total height, trunk diameter). The carbon captured was calculated from the estimate of forest biomass. The wood density of the different species was obtained from various global forestry databases. 68 species and 1200 individuals were identified. The most abundant species was Azadirachta indica (37%). CO2 sequestration was 19 650.76 t. Although a significant amount of carbon is fixed, many specimens are in conflict with physical infrastructure, which requires their removal. It is recommended to design new green areas under strict quality standards, prioritizing native species., A importância das árvores para o ambiente centra-se nos serviços que podem oferecer, sendo a fixação de CO2 um dos mais destacados. O objetivo da pesquisa foi estimar a quantidade de carbono capturada pelas árvores nas áreas verdes da Universidad Laica Eloy Alfaro de Manabí. Para tanto, foi realizado um inventário do estrato arbóreo. Todos os indivíduos com diâmetro de 1.30 m (mais menos 5 cm) foram registrados. Foram avaliadas a riqueza e abundância, bem como as variáveis dendométricas (altura total, diâmetro do tronco). O carbono capturado foi calculado a partir da estimativa da biomassa florestal. A densidade da madeira das diferentes espécies foi obtida de vários bancos de dados florestais globais. 68 espécies e 1200 indivíduos foram identificados. A espécie mais abundante foi Azadirachta indica (37%). O sequestro de CO2 foi de 19 650.76 t. Embora uma quantidade significativa de carbono seja fixada, muitos espécimes estão em conflito com a infraestrutura física, o que exige sua remoção. Recomenda-se projetar novas áreas verdes sob rígidos padrões de qualidade, priorizando espécies nativas.

South Africa is the largest CO2 emitter on the African continent. These emissions stem from a heavy reliance on coal as the primary energy fuel and contributor toward socio-economic development. The South African government has targeted reducing CO2 emissions by more than half in the next 10 years. To meet climate change mitigation scenarios, while alleviating continued emissions, South Africa will look to technologies such as carbon capture, utilisation and storage. Initial assessments of South Africa’s potential for CO2 storage have focused on deep saline aquifers within volcano-sedimentary sequences along the near and offshore regions. Sustaining the Just Transition will, however, require additional storage capacity. In this study, we make an initial assessment of possible CO2 storage in basaltic sequences of the Ventersdorp Supergroup. Geological and mineralogical information was ascertained from borehole data. The geological information suggests that the subsurface extent of the Ventersdorp Supergroup is at least 80 000 km2 larger than previously mapped, extending beneath major point-source CO2 emitters and active coalfields. Furthermore, petrographic analyses suggest pore space of up to ca 15% with minimal alteration, and preservation of mafic silicate minerals that would enable reactive carbonation of injected CO2. Notable metasomatic and hydrothermal alteration is confined to significant contact horizons, such as the lowermost Ventersdorp Contact Reef. These results suggest that basaltic sequences may exponentially increase South Africa’s CO2 sequestration storage capacity and may have a significant impact on the country’s Just Transition. Significance: This study shows that basaltic sequences may support the permanent storage of anthropogenic CO2 in South Africa, in particular, proximal to significant point-source CO2 emitters. South Africa has voluminous and widespread basaltic sequences, which, in combination, increase South Africa’s geological CO2 storage potential by several orders of magnitude. These storage reservoirs can have a direct impact in South Africa by enabling a sustainable Just Transition toward a low-carbon economy while meeting intended climate change mitigation scenarios.

The record floods experienced along the Tisza River between 1998 and 2001 brought a paradigm shift in infrastructural solutions for flood protection. A flood peak polder system was built for transient water storage without any substantial change in land use in the polders, despite the potential to do so under the new scheme. The recent improvement of quantified flood risk assessment methodologies and stronger foundations for the valuation of carbon sequestration benefits now provide more information on the magnitude of missed opportunities and the potential for comprehensive land use and flood risk management solutions. This paper evaluates and combines the results of three cost-benefit type analyses on the conflicting relations of pursuing flood risk mitigation and land management goals. Although the studies were conducted at different locations of the same river stretch, they are all inspected using the same flood waves. Results assert that as EU-CAP agricultural subsidies stabilize individual benefits from arable land use in the short-run, public benefits and long-term individual benefits fail to reach their potential value. The combined analysis of flood risk change and CO2 sequestration provides the economic rationale for the ecological revitalization along rivers with flood peak polders, helping to solve the conflict between hydrological and ecological objectives in floodplains. Capitalizing the value of the community benefits of forests in terms of CO2 sequestration is limited by the unresolved property rights allocation of this natural capacity between landowners and the state, the latter being responsible for fulfilling international CO2 reduction agreements; this uncertain legal background is an obstacle to the creation of sustainable economic conditions for the development and expansion of beneficial land management processes along rivers.

We perform large-scale numerical simulations to study Rayleigh–Darcy convection in three-dimensional fluid-saturated porous media up to Rayleigh–Darcy number $Ra=8\times 10^4$ . At these large values of $Ra$ , the flow is dominated by large columnar structures – called megaplumes – which span the entire height of the domain. Near the boundaries, the flow is hierarchically organized, with fine-scale structures interacting and nesting to form larger-scale structures called supercells. We observe that the correlation between the flow structure in the core of the domain and at the boundaries decreases only slightly for increasing $Ra$ , and remains rather high even at the largest $Ra$ considered here. This confirms that supercells are the boundary footprint of megaplumes dominating the core of the domain. In agreement with available literature predictions, we show that the thickness of the thermal boundary layer scales very well with the Nusselt number as $\delta \sim 1/ Nu$ . Measurements of the mean wavenumber – inverse of the mean length scale – in the core of the flow support the scaling $\bar {k} \sim Ra^{0.49}$ , in very good agreement with theoretical and numerical predictions. Interestingly, the behaviour of the mean wavenumber near the boundaries scales as $\bar {k} \sim Ra^{0.81}$ , which is distinguishably different from the presumed linear behaviour. We hypothesize that a linear behaviour can only be observed in the ultimate regime, which we argue to set in only at $Ra$ in excess of $5\times 10^5$ , whereas a sublinear behaviour is recovered at more modest $Ra$ . The present results are expected to help the development of long desired reliable models to predict the large- and fine-scale structure of Rayleigh–Darcy convection in the high- $Ra$ regime typically encountered in geophysical processes, such as for instance in geological carbon dioxide sequestration.

The geological sequestration of CO2 in deep saline aquifers is one of the most effective strategies to reduce greenhouse emissions from the stationary point sources of CO2. However, it is a complex task to quantify the storage capacity of an aquifer as it is a function of various geological characteristics and operational decisions. This study applies physics-based proxy modeling by using multiple machine learning (ML) models to predict the CO2 trapping scenarios in a deep saline aquifer. A compositional reservoir simulator was used to develop a base case proxy model to simulate the CO2 trapping mechanisms (i.e., residual, solubility, and mineral trapping) for 275 years following a 25-year CO2 injection period in a deep saline aquifer. An expansive dataset comprising 19,800 data points was generated by varying several key geological and decision parameters to simulate multiple iterations of the base case model. The dataset was used to develop, train, and validate four robust ML models—multilayer perceptron (MLP), random forest (RF), support vector regression (SVR), and extreme gradient boosting (XGB). We analyzed the sequestered CO2 using the ML models by residual, solubility, and mineral trapping mechanisms. Based on the statistical accuracy results, with a coefficient of determination (R2) value of over 0.999, both RF and XGB had an excellent predictive ability for the cross-validated dataset. The proposed XGB model has the best CO2 trapping performance prediction with R2 values of 0.99988, 0.99968, and 0.99985 for residual trapping, mineralized trapping, and dissolution trapping mechanisms, respectively. Furthermore, a feature importance analysis for the RF algorithm identified reservoir monitoring time as the most critical feature dictating changes in CO2 trapping performance, while relative permeability hysteresis, permeability, and porosity of the reservoir were some of the key geological parameters. For XGB, however, the importance of uncertain geologic parameters varied based on different trapping mechanisms. The findings from this study show that the physics-based smart proxy models can be used as a robust predictive tool to estimate the sequestration of CO2 in deep saline aquifers with similar reservoir characteristics.

Mineral carbonation is one of the most effective and widely used climate change mitigation technologies. Regardless of its efficiency, it is slow and energy intensive. The effectiveness and reactivity of different Alkali-feedstocks under different process conditions and parameters are investigated in this work using intensified mineral carbonation in a ball mill reactor. Different analyses were performed on the carbonated materials. The findings revealed that the reaction worked and that several carbonates were formed even though the reactor was not initially designed for this purpose. Then, an energy assessment and a life-cycle assessment of the process were provided to investigate the process costs and environmental concerns. The findings highlighted the process's potential for larger-scale implementation, as well as the use of carbonated minerals as a cement substitute in future building materials. Mitacs globalink

Compressed energy storage (CES) of air, CO2, or H2 in porous formations is a promising means of energy storage to abate the intermittency of renewable energy production. During operation, gas is injected during times of excess energy production and extracted during excess demands to drive turbines. Storage in saline aquifers using CO2 as a cushion or working gas has numerous advantages over typical air storage in caverns. However, interactions between CO2 and saline aquifers may result in potential operational limitations and have not been considered. This work utilizes reactive transport simulations to evaluate the geochemical reactions that occur during injection and extraction operational cycles for CES in a porous formation using CO2 as a cushion gas. Simulation results are compared with similar simulations considering an injection-only flow regime of geologic CO2 storage. Once injected, CO2 creates conditions favorable for dissolution of carbonate and aluminosilicate minerals. However, the dissolution extent is limited in the cyclic flow regime where significantly smaller dissolution occurs after the first cycle such that CO2 is a viable choice of cushion gas. In the injection-only flow regime, larger extents of dissolution occur as the fluid continues to be undersaturated with respect to formation minerals throughout the study period and porosity increased uniformly from 24.84% to 33.6% throughout the simulation domain. For the cyclic flow conditions, porosity increases nonuniformly to 31.1% and 25.8% closest and furthest from the injection well, respectively.

The paper addresses the problem of geomechanical effects in the vicinity of production/injection wells and their impacts on the processes of enhanced oil recovery by CO2 injection and CO2 sequestration in a partially depleted oil reservoir. In particular, it focuses on natural fracture systems and their dynamics caused by variations in the rock geomechanical state due to reservoir pressure changes during production/injection processes. The comprehensive approach to the problem requires the combined modeling of both geomechanical and flow phenomena associated with effective coupling simulations of their evolution. The paper applies such an approach to a real, partially depleted oil reservoir in Poland. An effective method of coupled geomechanical and dynamic simulations was used together with the natural boundary and initial conditions for both simulation types. In addition, typical operating conditions were applied in analyzing the processes of enhanced oil recovery by CO2 injection and CO2 sequestration. The detailed results of relevant modeling and simulations are presented and discussed focusing on various scale consequences, including the reservoir, well, and completion ones. Both general conclusions as well as the ones specific to the analyzed geological structure are drawn; they confirm the significant dependence of well performance on geomechanical effects and point out several key factors for this dependence. The conclusions specific to the analyzed structure concern fracture reactivation in tensile/hybrid failure mode caused by pressure build-up during CO2 injection and the importance of the fracture-induced aperture changes resulting from the normal stress, while the shear stress is found to be negligible.

Experimental studies have confirmed the permeability reduction of coal samples upon the adsorption of CO2. However, these studies were carried out under limited experimental conditions. In this study, CO2 flow behaviors in a macro-scale coal sample were numerically simulated using a coupled gas flow, mechanical deformation, and sorption-induced deformation finite element model. The simulation results show that the effect of the reduction of effective stress on the enhancement of permeability is greater than the negative effect of permeability reduction due to CO2 adsorption for low injection pressures. CO2 pressure development in the sample increases with increasing injection pressure due to the enhanced advection flux for sub-critical CO2 injections, while for super-critical CO2 injections, CO2 pressure development, as well as concentrations in the sample, decreases compared to sub-critical CO2 injections because of greater density and viscosity of super-critical CO2 as well as coal matrix swelling induced by the adsorption of super-critical CO2. Increasing axial stress (buried depth) obstructs CO2 migration in the sample due to the increased effective stress, and this effect is more influential for low injection pressures, which indicates that high CO2 injection pressures are preferred for CO2 sequestration in deep coal seams.

Recently there have been significant advances in the viscosification of CO2 using a low concentration of oligomers. The new engineered molecules do not adsorb onto rock. This paper studies the effects of different CO2-enhanced viscosity levels in subsurface aquifers and reservoirs. The study was conducted using numerical modeling and simulation tools in homogeneous, heterogenous, fractured, and unfractured media. The viscosity enhancement of CO2 varied from 2- to 20-fold. The simulations included homogeneous, layered, and fractured domains in 2D and in 3D for improved oil recovery. The results showed that in unfractured, homogenous, and layered media, a 10-fold viscosity increase leads to significant increases in oil recovery. In a fractured medium with a highly connected fracture network, a 20-fold viscosity enhancement may have a considerable effect in delaying breakthrough and improving oil recovery. Simulations were performed in a compositional three-phase flow based on higher-order discretization. The algorithm included Fickian diffusion, which may add to oil recovery performance when there is a sufficient surface area between the CO2-rich phase and the oil phase. In CO2 sequestration, an increase in the viscosity of CO2 and consequent mobility control promotes CO2 dissolution in the aqueous phase. Due to the increase in the density of the aqueous phase from CO2 dissolution, the CO2 is carried away from the cap rock to the bottom of the formation. This work is of particular importance in improved oil recovery and in safe CO2 sequestration due to solubility trapping and mitigation of pressure increase. The higher-order numerical scheme used in this simulation guarantees a level of accuracy not obtained in traditional simulators.

Injecting power plant flue gas into a goaf stores CO2 in the flue gas and effectively prevents the spontaneous combustion of the coal remaining in the goaf. Here, we investigated the adsorption behavior of three types of coal at normal temperature and pressure using a self-developed adsorption experimental device. We used a specific surface area and porosity analyzer to study the effects of pore structure, mineral content, and moisture content on CO2 adsorption in coal. Based on the experimental data, we designed a multifactor CO2 adsorption prediction model based on a backpropagation (BP) neural network. The results indicated that the pore size of most micropores in coal was in the range of 0.5–0.7 and 0.8–0.9 nm. The specific surface area and pore volume were positively correlated with the CO2-saturated adsorption capacity, whereas the mean pore diameter, mineral content, and moisture content were inversely associated with the CO2-saturated adsorption amount. The accuracy of the multifactor BP neural network prediction model was satisfactory: the determination coefficients (R2) of the training and test sets were both above 0.98, the root mean square error (RMSE) and mean absolute error (MAE) of the test set were both less than 0.1, and the prediction results satisfied the requirements. To optimize the prediction performance of the model, we used the random forest algorithm to calculate the importance of each factor. The sum of the importance weights of the specific surface area, moisture content, and pore volume was 91.6%, which was much higher than that of the other two factors. Therefore, we constructed an optimization model with specific surface area, moisture content, and pore volume as input variables. The R2 values of the training and test sets in the simplified model were improved compared with those of the multifactor model, the RMSE and MAE were reduced, and the fitting effect was ideal. The prediction model of CO2 adsorption in coal based on the BP neural network can predict the CO2 adsorption capacity of coal under different physical and chemical conditions, thereby providing theoretical support for the application of CO2 storage technology in goafs.

Reliable regional-scale permeability data and minimum sustained injectivity rate estimates are key parameters required to mitigate economic risk in the site selection, design, and development of commercial-scale carbon sequestration projects, but are seldom available. We used extensive publicly available disposal well data from over 4000 disposal wells to assess and history-match regional permeability estimates and provide the frequency distribution for disposal well injection rates in each of 66 disposal formations in the Alberta Basin. We then used core data and laboratory analyses from over 3000 cores to construct 3D geological, geomechanical and petrophysical models for 22 of these disposal formations. We subsequently used these models and the history-matched regional permeability estimates to conduct coupled geomechanical and reservoir simulation modeling (using the ResFrac™, Palo Alto, CA, USA, numerical simulator) to assess: (i) well performance in each formation when injecting carbon dioxide for a 20-year period; (ii) carbon dioxide saturation and reservoir response at the end of the 20-year injection period; (iii) reliability of our simulated rates compared to an actual commercial sequestration project. We found that: (i) the injection rate from our simulations closely matched actual performance of the commercial case; (ii) only 7 of the 22 disposal formations analyzed appeared capable of supporting carbon dioxide injectors operating at greater than 200,000 tons per year/well; (iii) three of these formations could support injectors operating at rates comparable to the successful commercial-scale case; (iv) carbon dioxide presence and a formation pressure increase of at least 25% above pre-injection pressure can be expected at the boundaries of the (12 km × 12 km) model domain at the end of 20 years of injection.

The possibility of utilizing non-ferrous slags for CO₂-mineralization is explored in this study by investigating their dissolution behaviors in CO₂-environments, since dissolution is usually considered as a major rate-limiting step during CO₂-mineralization. Dissolution of two copper slags and a lead slag are studied at the liquid to solid ratio (w/w) of 1000 at combinations of two temperatures (30 and 60 °C) and two CO₂-pressures (1 and 10 barg) with time (30, 60, 120, and 240 min). Among the systems in which the slags are dissolved in CO₂-environments, the lead slag exhibits Fe-dissolution of up to 10%, and the copper slags up to 5–6% within four hours. The solution-pH were between 4 and 5 in almost all the observations. The dissolution rates of the slags are found to be in the range of 10−7-10−9 mol/m²/s which are comparable with the dissolution of natural fayalite in (in)organic acids. Following the dissolution during the initial 30–60 min, the systems at a higher temperature (at constant CO₂-pressure) and higher CO₂-pressure (at constant temperature) exhibit higher (or comparable) [Ca], [Fe], [Si], and solution-pH. Moreover, even though the systems at higher temperature and CO₂-pressure exhibit higher solution-pH following the initial 30–60 min of dissolution, they continue to exhibit higher dissolution rates throughout the study. Since the residues like non-ferrous copper and lead slags are readily available compared to the analogous natural minerals (like olivines) that usually need to be pre-processed before carbonation, they are proposed as promising sources for CO₂-mineralization.

Investigating the adsorption characteristics of CO2, N2 and CH4 on kaolinite clay is beneficial for enhanced shale gas recovery by gas injection. In this paper, the experiments of CO2, N2 and CH4 adsorption at 288 K, 308 K and 328 K on kaolinite clay were conducted, and the thermodynamics analysis of adsorption of three gases was performed. The findings reveal that the order of the uptakes of three gases on kaolinite clay is as follows: N2

The investigation into the combined processes of CO2-EOR and geologic carbon sequestration was seen to be a viable solution to reducing CO2 emissions from the atmosphere, while boosting production from mature oil fields. However, the practicality of the combined process hinges on the determination of an optimum injection pressure to maximize the application of both methods. In addition, the success of these two operations is also contingent upon the dynamic sealing capacity of bounding faults, to allow hydrocarbon accumulation and trapping of injected CO2. Consequentially, the goal of this research is to optimize the implementation of combined CO2-EOR with simultaneous CO2 sequestration and investigate the enhancing/diminishing aspects of fault reactivation and CO2 migration. The study was approached from two scenarios; the first was the determination of an optimum injection pressure for the combined process, with the main focus on maximizing recovery from a mature oil field. The results saw a maximum cumulative recovery of 73.7090 Mbbls being facilitated at an optimal injection rate of 722 Scf/day. The second scenario entailed the investigation of the occurrence or lack thereof, of injection-induced fault reactivation at this predetermined injection rate of 722 Scf/day. Simulations reflecting the characteristics of fault reactivation were conducted, and are indicative of relations between fault opening stress, reactivation time, hydraulic fracture permeability, fracture propagation length, and leakage. Conclusively, the viability of the combination of CO2-EOR and sequestration were seen to depend on the technicalities of fault reactivation. In some cases, reactivation resulted in increases of accessible storage capacity, whereas, in other instances, it led to the leakage of the injected CO2.

Industrial activities for the phosphoric acid production cogenerate a large amount of phosphogypsum waste, emitting significant quantities of toxic gas in the surrounding environment. In the context of recovered materials to handle greenhouse gases more precisely CO2 as one of the most toxic gases responsible for the global climate change, an affordable and effective method for CO2 mineral sequestration using phosphogypsum by-product is developed in this investigation. The obtained results show the high efficiency of portlandite Ca(OH)2 resulting from the dispersion of phosphogypsum in alkaline potash solution followed by releasing of potassium sulphate as a co-product. Furthermore, the carbonation experiments show a total conversion of the Ca(OH)2 to calcium carbonate as final product at ambient temperature and atmospheric pressure. The approach suggested in this research shows permanent and safe solution to face the storage of phosphogypsum and carbon dioxide, which were causes a serious problems for the ecosystems and human health. As well as, the valorization of the co-products in different fields, e.g., potassium sulphate as a fertilizer while calcium carbonate has various uses as raw material for construction.

CO2 is one of the key greenhouse gases that cause climate change and various ways are being explored to curb CO2 emission in the atmosphere. Mineral carbonation method is one such technique to capture atmospheric CO2 and store it in a carbon sink. However, due to the high cost, the mineral sequestration process is preferred for small emitters (>2.5 Mt CO2). In this study, the mineral carbonation is explored to study its effectiveness in the process of CO2 sequestration. Further, the use of CO2 as a feedstock in the production of different industrial chemicals is explored. In the end, the efficacy of the mineral carbonation process in combating climate change is analyzed.

Spreading olivine powder in seawater to enhance alkalinity through weathering reactions has been proposed as a potential solution to control atmospheric CO2 concentration. Attention has usually been paid to the chemical properties of seawater after the addition of olivine within lab and modeling studies. However, both microbial acclimation and evolution in such manipulated natural environments are often overlooked, yet they are of great importance for understanding the biological consequences of whether olivine addition is a feasible approach to mitigating climate change. In this study, an olivine addition experiment was conducted to investigate variation in bacterial diversity and community composition in the surface and bottom seawater of a representative marine ranch area in the Muping, Yantai. The results show that the composition of the particle-attached microbial community was particularly affected by the application of olivine. The relative abundance of biofilm-forming microbes in particle-attached fraction increased after the addition of olivine, while no significant variation in the free-living bacterial community was observed. Our study suggests that olivine addition would reshape the bacterial community structure, especially in particle-attached microenvironments. Therefore, the risk evaluation of alkalinity enhancement should be further studied before its large-scale application as a potential ocean geoengineering plan.

The present German energy policy is focussed on further increase of renewable capacity and power consumption to achieve net zero GHG emissions by 2045 while maintaining security of energy supply. The planned pace of the rollout of renewables looks ambitious but feasible and could result in phasing out substantial volumes of unabated coal-fired power production by 2030. However, it will miss the net zero target in 2045 by decades even if the issues surrounding the low readiness level of electrolysis and yet-to-be-provided hydrogen infrastructure, especially storage, could be resolved in time. For a realistic chance to meet net zero in 2045 adding an ambitious CO2 capture and sequestration policy is essential. The present German legislation bars CO2 sequestration but CO2 capture and transport for export are explicitly possible. Norway with a sequestration potential of 70 Gt CO2 would be an obvious partner for Germany, but such a partnership would require the introduction of missing German standards and procedures to handle CO2 and ratifying the amendment of the London protocol by Germany. By adding a pragmatic CO2 sequestration policy such as those in the US, UK and the Netherlands, Germany would have a realistic chance to reach net zero by 2045 without jeopardizing its industrial basis.

The increased concern about climate change is revolutionising the building materials sector, making sustainability and environmental friendliness increasingly important. This study evaluates the feasibility of incorporating recycled masonry aggregate (construction and demolition waste) in porous cement-based materials using carbonated water in mixing followed (or not) by curing in a CO2 atmosphere. The use of carbonated water can be very revolutionary in cement-based materials, as it allows hydration and carbonation to occur simultaneously. Calcite and portlandite in the recycled masonry aggregate and act as a buffer for the low-pH carbonated water. Carbonated water produced better mechanical properties and increased accessible water porosity and dry bulk density. The same behaviour was observed with natural aggregates. Carbonated water results in an interlaced shape of carbonate ettringite (needles) and fills the microcracks in the recycled masonry aggregate. Curing in CO2 together with the use of carbonated water (concomitantly) is not beneficial. This study provides innovative solutions for a circular economy in the construction sector using carbonated water in mixing (adsorbing CO2), which is very revolutionary as it allows carbonation to be applied to in-situ products.

Mineral carbonation of construction and demolition waste is a viable alternative for the reduction of CO2 emissions from industry. Concrete and cement, together with ceramic blocks, are the primary sources of calcium for mineral carbonation in which CO2 is fixed in a stable and inert process. One type of concrete was selected from 5 for the carbonation tests. Crushed, separated into size fractions, moistened to 20% and tested at 10 bars of CO2 for 24 to 720h. Destruction of portlandite and ettringite phases was determined. Calcite precipitated as carbonate phase. Maximum carbonation was reached after 72h, fixing 6.5% of CO2. La carbonatación mineral de los residuos de construcción y demolición es una alternativa viable para la reducción de las emisiones de CO2 de la industria. El hormigón y el cemento, junto con los bloques de cerámica, son las principales fuentes de calcio para la carbonatación mineral en la que el CO2 se fija en un proceso estable e inerte. Se seleccionó un tipo de hormigón de entre 5 para las pruebas de carbonatación. Triturado, separado en fracciones de tamano, ˜ humedecido al 20% y probado a 10 bares de CO2 durante 24 a 720 horas. Se determinó la destrucción de las fases de portlanita y ettringita. La calcita se precipitó como fase de carbonato. La máxima carbonatación se alcanzó después de 72 horas, fijando el 6,5% de CO2. Junta de Andalucía P12-RNM-568

Since 1980, one of the most promising solutions for the exploitation of natural gas hydrate reservoirs was found to be the replacement of methane with carbon dioxide in order to improve the efficiency of methane recovery and, at the same time, permanently store carbon dioxide. However, the process efficiency is still too low and far from reaching technical maturity and becoming economically competitive. In this sense, studying the intrinsic properties of CO2 hydrates formation and dissociation processes may help in better defining the reasons for this low efficiency and finding feasible solutions. This work deals with carbon dioxide hydrates formation in a natural silica-based porous medium and in fresh water. A lab-scale apparatus was used for experiments, which were carried out consecutively and with the same gas–water mixture in order to detect the possible occurrence of the “memory effect”. Six tests were carried out: the quantity of gas available for the formation of hydrates led to an initial pressure equal to 39.4 bar within the reactor (the initial pressure was 46 bar; however, the dissolution of CO2 in water during the first test caused a reduction in the quantity of gas available for the process). Each experiment started and ended at temperatures equal or higher than 20 °C. Considering the local pressures, these temperatures ensured the complete dissociation of hydrates. Besides thermodynamic parameters, the gas consumption and the rate constant were evaluated throughout the whole of the experiments. Conversely to what is asserted in the literature, the results demonstrated the weak persistence of the memory effect at a temperature slightly above 25 °C. As expected, ice formation competed with hydrates; however, during tests, it caused the partial release of carbon dioxide previously trapped into hydrates or dissolved in water. Finally, the rate constant completely agreed with the labile Cluster Theory and proved that primordial clusters and hydrate crystals formed and dissociated during the whole test. The first phenomenon was predominant during the formation phase, while the opposite occurred during the following step. The rate constant was found to be an effective parameter to quantify differences between measured and real equilibrium conditions for the system.

Η παρούσα έρευνα με θέμα «Τεχνητή επιλογή υψηλοπαραγωγικών κλώνων ταχυαυξών δασικών ειδών για δέσμευση διοξειδίου του άνθρακα και παραγωγή βιοενέργειας», έχει ως κύριο σκοπό τη μελέτη των χαρακτηριστικών των φυτειών ταχυαυξών δασικών ειδών και του τρόπου με τον οποίο μπορούν να χρησιμοποιηθούν αποδοτικότερα για την παραγωγή βιομάζας. Για την επίτευξη του σκοπού αυτού αρχικά συγκεντρώθηκε η υπάρχουσα βιβλιογραφία και έγινε συλλογή των απαραίτητων δεδομένων της μέσης παραγωγής βιομάζας για κάθε κλώνο ανά είδος (λεύκη, ψευδακακία, πλάτανος). Έπειτα έλαβαν χώρα υπολογισμοί του μέσου όρου καθώς και της τυπικής απόκλισης αναφορικά με την παραγωγή βιομάζας και υπολογίστηκε το γενετικό κέρδος κάθε είδους, ο ρυθμός του ανά έτος και η αναμενόμενη παραγωγή στην επόμενη γενιά. Έχοντας ως βάση την αναμενόμενη παραγωγή στην επόμενη γενιά και μέσω καταλλήλων μετατροπών έγινε η αναγωγή στο ποσό της δέσμευσης του διοξειδίου του άνθρακα και η εκτίμηση της παραγόμενης βιοενέργειας. Σύμφωνα με τα αποτελέσματα όσο λιγότεροι κλώνοι εμπλέκονται σε μια φυτεία, τόσο μεγαλύτερο είναι το γενετικό κέρδος και η αναμενόμενη παραγωγή (εφόσον βέβαια η επιλογή γίνεται από το υψηλοπαραγωγικότερο προς το λιγότερο παραγωγικό κλώνο) με τη διαφορά αμιγούς από μικτές φυτείες να κυμαίνεται από 24%-35%.Συμπερασματικά οι αμιγείς και μικτές φυτείες ταχυαξών δασικών ειδών με χρήση γενετικά βελτιωμένου υλικού στην Ελλάδα παρουσιάζουν υψηλές δυνατότητες παραγωγής βιομάζας, υψηλό ενεργειακό δυναμικό και υψηλή ικανότητα δέσμευσης CO2., The present study on "Artificial selection of elite fast-growing clones for carbon dioxide sequestration and bioenergy production", has as its main purpose the study of the characteristics of fast-growing forest species and how they can be used more efficiently for biomass production. To achieve this goal, the existing literature was initially compiled and the necessary data on the average biomass production for each species were collected (Populus, Robinia pseudoacacia, Platanus). Then the calculation of the average and the standard deviation, regarding the production of biomass took place as well as the genetic gain of each species, its rate per year and the expected production in the next generation. Based on the expected production in the next generation and using the appropriate altitude number and the conversion factor, it was reduced to the amount of carbon dioxide sequestration and the generated bioenergy. According to the results the fewer clones we use in a plantation, the bigger is the genetic gain and the produced biomass (provided that the choice is from the highest productive clone to the lowest one), with the difference of pure and mixed plantation ranged from 24% to 35%. In conclusion pure and mixed plantation of fast-growing forest tree species with the usage of genetically diversity material in Greece present high potentials for biomass production, high energy potential and high capacity for CO2 sequestration.

Coal seam gas is an important energy resource worldwide. The methane extraction from coal seam is often accompanied by CO2 injection to enhance the gas recovery and reduce the greenhouse gas emission footprint. Amongst all processes active in coal seam gas extraction, understanding and characterizing the coal effective stress and its evolution with time need special attention. The reservoir characteristics of coal seam that control its effective stress evolution, however, differ from that of other hydrocarbon resources in granular sediments. In conventional reservoirs, it is the pore volume determining the gas storage, but in coal seams, it is the pore surface area that defines the capacity through adsorption. As naturally fractured reservoirs, coal seams often contain an extensive fracture network called cleats thus, the coupled relationship between the mechanical behaviour and sorption effect can significantly influence the effective stress and in turn permeability. The main aim of this dissertation is thus to investigate and model the interaction of effective stress evolution and adsorption/desorption processes using advanced and innovative laboratory experiments and numerical simulations. This dissertation includes four parts consisting of the modelling and fundamental studies employing novel experimental and numerical techniques. The first part of the dissertation seeks to understand the characteristics of sorption-hydromechanical behaviour through the microscale and non-destructive investigation using micro-computed tomography (μCT), ultrasonic and their combined measurements. These fundamental investigations shed light on the coupled physical processes in different coal samples extracted from the Sydney Basin Australia through tracking 3D internal geometry. Using an X-ray transparent triaxial system, a range of stress-pore pressure boundary conditions are applied on different coals to obtain the 3D internal structure. The different coal components and their fracture patterns are analysed with respect to the bulk, matrix, and fracture compressibilities. In a further step, the coupled stress and swelling strain responses of coal when exposed to carbon dioxide (CO2) and helium (He) are studied by imbedding ultrasonic sensors in the X-ray transparent triaxial system. With the real-time visualisation of fracture porosity due to different adsorption levels, the effects of CO2 adsorption and involved processes on ultrasonic responses are investigated. The combined physical and numerical methods determine the main factor influencing wave propagation in coal to i) assist developing the representative constitutive model and ii) be used in the acoustic-driven parameterisation in the final part of the dissertation. The micro-scale investigation highlights the importance of internal structure affecting the mechanical properties in coal and the acoustic wave velocity allows evaluating the changes in facture characteristics during CO2 adsorption. Using detailed understanding of the physical processes involved in coal multiphysics, a constitutive model based on the continuum mechanics and non-equilibrium thermodynamics is developed in the second part of the dissertation. The model considers changes in gas content in the tight coal matrix through sorption and diffusion processes along with gas leakage from the matrix into fractures where Darcy type flow takes place. Also, the time dependency of coupling processes is accounted for especially the volumetric strains induced by gas sorption and their overall effects on changes in the fracture aperture, hence in the bulk flow conductivity. The novelty of the proposed model specially lies in the derivation of the thermodynamically consistent formulation of time-dependent effective stress law. The next part of the dissertation seeks to validate the developed effective stress law experimentally and to investigate i) the performance of commonly used theoretical models for swelling stress estimation, ii) the validity of thermodynamics coupling coefficient defining the swelling stress and iii) the effect of external stress on coal volumetric strain response. Especially designed experiments on two coal samples are conducted, including time-dependent diffusion and volumetric strain experiments under various stress and CO2 pressure conditions. A new experimental method is proposed to characterize the key input of the model which is the swelling coupling coefficient. Results of these series of experiments also show that the stress induced compression has minor effect on gas desorption. Since the wave velocity and porosity are interrelated, in the last part of the dissertation, some key parameters involved in the set of developed hydromechanical relationships are measured/modelled using acoustic measurement and finite element simulation. First, the effective stress coefficient is predicted using the percolation theory and hydromechanical and ultrasonic laboratory measurements on coal samples. The swelling coefficient representing adsorption induced volumetric strain development is next studied using acoustic simulation. As a newly proposed coupling coefficient in the model development, the relationship between the coefficient and wave velocity are correlated in three pore pressure conditions and its response to each condition is collected and analysed. Finally, the fracture permeability in coal seams is estimated using a novel physics-informed neural network (PINN) technique. In the training of PINN model, a synthetic dataset is built from several ultrasonic measurements and numerical simulations, with input variables of wave velocity and density. This model is successfully applied in a field case study where downhole geophysical logging data is available. In general, the acoustic-driven technique provides a strong and useful pathway to predict model parameters using geophysical logging data in a field setting, where sonic logs are available.

In this study, we explored the capability of coda wave interferometry (CWI) for monitoring CO2 storage by estimating the seismic velocity changes caused by CO2 injection. Given that the CWI method is highly efficient, the primary aim of this study was to provide a quick detection tool for the long-term monitoring of CO2 storage safety. In particular, we looked at monitoring with a cross-well geometry. We also expected that CWI could help to reduce the inversion errors of existing methods. Time-lapse upgoing waves and downgoing waves from two-component datasets were utilized to efficiently monitor the area between the wells and provide a quick indication of possible CO2 leakage. The resulting mean velocity changes versus the depth indicated the depth where velocity changes occurred. Combining the upgoing and downgoing wavefields provided a more specific indication of the depth range for changes. The calculated velocity changes were determined using the time shift between the time-lapse wavefields caused by CO2 injection/leakage. Hence, the resulting velocity changes were closely related to the ratio of propagation path length through the CO2 injection/leakage layer over the length of the entire travel path. The results indicated that the noise level and repeatability of the time-lapse datasets significantly influenced the results generated using CWI. Therefore, denoising and time-lapse processing were very important for improving the detectability of any change. Applying CWI to time-lapse cross-well surveys can be an effective tool for monitoring CO2 in the subsurface at a relatively low computational cost. As a highly efficient monitoring method, it is sensitive to changes in the seismic response caused by velocity changes in the subsurface and provides additional constraints on the inversion results from conventional travel time tomography and full waveform inversion.

Strategies for depleting carbon dioxide (CO2) from flue gases are urgently needed and carbonic anhydrases (CAs) can contribute to solving this problem. They catalyze the hydration of CO2 in aqueous solutions and therefore capture the CO2. However, the harsh conditions due to varying process temperatures are limiting factors for the application of enzymes. The current study aims to examine four recombinantly produced CAs from different organisms, namely CAs from Acetobacterium woodii (AwCA or CynT), Persephonella marina (PmCA), Methanobacterium thermoautotrophicum (MtaCA or Cab) and Sulphurihydrogenibium yellowstonense (SspCA). The highest expression yields and activities were found for AwCA (1814 WAU mg−1 AwCA) and PmCA (1748 WAU mg−1 PmCA). AwCA was highly stable in a mesophilic temperature range, whereas PmCA proved to be exceptionally thermostable. Our results indicate the potential to utilize CAs from anaerobic microorganisms to develop CO2 sequestration applications.

The cyclic injection of CO2, referred to as the huff-n-puff (HnP) method, is an attractive option to improve oil recovery from unconventional reservoirs. This study evaluates the optimization of the CO2 HnP method and provides insight into the aspects of CO2 sequestration for unconventional reservoirs. Furthermore, this study also examines the impact of nanopore confinement, fluid composition, injection solvent, diffusivity parameters, and fracture properties on the long-term recovery factor. The results from over 500 independent simulations showed that the optimal recovery is obtained for the puff-to-huff ratio of around 2.73 with a soak period of fewer than 2.7 days. After numerous HnP cycles, an optimized CO2 HnP process resulted in about 970-to-1067-ton CO2 storage per fracture and over 32% recovery, compared to 22% recovery for natural depletion over the 30 years. The optimized CO2 HnP process also showed higher effectiveness compared to the N2 HnP scenario. Additionally, for reservoirs with significant pore confinement (pore size ≤ 10 nm), the oil recovery improved by over 3% compared to the unconfined bulk phase properties. We also observed over 300% improvement in recovery factor for a fluid with a significant fraction of light hydrocarbons (C1–C6), compared to just a 50% improvement in recovery for a fluid with a substantial fraction of heavy hydrocarbons (C7+). Finally, the results also showed that fracture properties are much more important for CO2 HnP than natural depletion. This study provides critical insights to optimize and improve CO2 HnP operations for different fluid phases and fracture properties encountered in unconventional reservoirs.

CO2 injection technology into coal seams to enhance CH4 recovery (CO2-ECBM), therefore presenting the dual benefit of greenhouse gas emission reduction and clean fossil energy development. In order to gaze into the features of CO2 injection’s influence on reservoir pressure and permeability, the Thermal-Hydraulic-Mechanical coupling mechanism of CO2 injection into the coal seam is considered for investigation. The competitive adsorption, diffusion, and seepage flowing of CO2 and CH4 as well as the dynamic evolution of fracture porosity of coal seams are considered. Fluid physical parameters are obtained by the fitting equation using MATLAB to call EOS software Refprop. Based on the Canadian CO2-ECBM project CSEMP, the numerical simulation targeting shallow low-rank coal is carried out, and the finite element method is used in the software COMSOL Multiphysics. Firstly, the direct recovery (CBM) and CO2-ECBM are compared, and it is confirmed that the injection of CO2 has a significant improvement effect on methane production. Secondly, the influence of injection pressure and temperature is discussed. Increasing the injection pressure can increase the pressure difference in the reservoir in a short time, so as to improve the CH4 production and CO2 storage. However, the increase in gas injection pressure will also lead to the rapid attenuation of near-well reservoir permeability, resulting in the weakening of injection capacity. Also, when the injection temperature increases, the CO2 concentration is relatively reduced, and the replacement effect on CH4 is weakened, resulting in a slight decrease in CBM production and CO2 storage.

Carbon-dioxide-enhanced shale gas recovery technology has significant potential for large-scale emissions reduction and can help achieve carbon neutrality targets. Previous theoretical studies mainly focused on gas adsorption in one-dimensional pores without considering the influence from the pore geometry. This study evaluates the effects of pore shape on shale gas adsorption. The pure and competitive gas adsorption processes of CO2 and CH4 in nanopores were investigated using molecular simulations to improve the prediction of shale gas recovery efficiency. Meanwhile, quantitative analysis was conducted on the effects of the pore shape on the CO2-EGR efficiency. The results indicate that the density of the adsorption layer in pores is equally distributed in the axial direction when the cone angle is zero; however, when the cone angle is greater than zero, the density of the adsorption layer decreases. Smaller cone-angle pores have stronger gas adsorption affinities, making it challenging to recover the adsorbed CH4 during the pressure drawdown process. Concurrently, this makes the CO2 injection method, based on competitive adsorption, efficient. For pores with larger cone angles, the volume occupied by the free gas is larger; thus, the pressure drawdown method displays relatively high recovery efficiency.

The purpose of this paper is to discover the impacts of contradictory factors in the application of agricultural residue with sustainable biofuel benefits. Based on the Life cycle assessment (LCA) approach, the quantitative LCA assessment model and approach have been established, coupling upstream cultivation and downstream jet biofuel product, which would benefit agriculture residue choice. The LCA model investigated the effects of interaction factors on energy consumption, including land release and agriculture residue use change. The computational framework of the LCA model is classified into three sub-models, including the cultivation and harvesting model, the refining process and distribution model, and the flight model. According to uncertainty analysis by the LCA model, the positive energy gains have been conducted at a wide range of hydrogen production and methanol production. The application model is represented by six types of typical aircraft widely used in China, including the LTO cycle module, actual cruising distance and maximum cruising distance module, actual payload, and maximum payload module. In the whole life cycle assessment, GHGs of agriculture residue is 17.9 gCO2e/MJ while petroleum-based jet fuel is 90.2 gCO2e/MJ. The order of GHGs in WTW (well to wheel) is agriculture residue < corn stover < beanstalk < wheat straw < rice straw. The land release conducted obviously to the total GHGs emission for rice straw, which indicated that land release should involve in the LCA.

To prevent drastic climate changes due to global warming, it is necessary to transition to a carbon-neutral society by reducing greenhouse gas emissions in all industrial sectors. This study aimed to develop carbon utilization sequestration technology that uses the concrete slurry water generated during the production of concrete as a new CO2 sink to reduce CO2 emissions from the cement industry. This was achieved by performing supercritical CO2 carbonation by varying the concrete slurry waste (CSW) ratio. The study’s results confirmed that, according to the CSW ratio (5 to 25%), complete carbonation occurred within only 10 min of the reaction at 40 °C and 100 bar.

The possibility of impure carbon dioxide (CO2) sequestration can reduce the cost of these projects and facilitate their widespread adoption. Despite this, there are a limited number of studies that address impure CO2 sequestration aspects. In this study, we examine the convection–diffusion process of the CO2–nitrogen (N2) mixture dissolution in water-saturated porous media through numerical simulations. Cross-diffusion values, as the missing parameters in previous studies, are considered here to see the impact of N2 impurity on dissolution trapping in more realistic conditions. Homogeneous porous media are used to examine this impact without side effects from the heterogeneity, and then simulations are extended to heterogeneous porous media, which are a good representative of the real fields. Heterogeneity in the permeability field is generated with sequential Gaussian simulation. Using the averaged dissolved CO2 and dissolution fluxes for each case, we could determine the onset of different dissolution regimes and behaviors of dissolution fluxes in CO2–N2 mixture dissolution processes. The results show that there is a notable difference between the pure cases and impure cases. Additionally, a failure to recognize the changes in the diffusion matrix and cross-diffusion effects can result in significant errors in the dissolution process. At lower temperatures, the N2 impurity decreases the amount and flux of CO2 dissolution; however, at higher temperatures, sequestrating the CO2–N2 mixture would be a more reasonable choice due to enhancing the dissolution behavior and lowering the project costs. The results of the heterogeneous cases indicate that heterogeneity, in most cases, reduces the averaged dissolved CO2, and dissolution flux and impedes the onset of convection. We believe that the results of this study set a basis for future studies regarding the CO2–N2 mixture sequestration in saline aquifers.

CO2 sequestration in coal is mainly attributed to adsorption. The adsorption experiments of CO2 were conducted at injection pressures ranging from 1 to 3 MPa on coal samples with five kinds of particle sizes. The fitting degree of four classical adsorption models to experimental adsorption data was systematically compared. The adsorption properties of CO2 were comprehensively discussed. The temperature changes of coal samples at different positions during CO2 adsorption were measured by using the improved adsorption tank, and then the energy conversion law was obtained. The results showed increasing gas injection pressure can effectively increase the adsorption capacity of CO2 on coal samples. The BET equation had the best fitting accuracy for CO2 adsorption on various size coal samples. There was a significant exothermic effect during CO2 adsorption and storage. With the rise of injection pressure, the peak value of the rising temperature of coal samples increased, but the change rate decreased. The maximum temperature rise of coal samples was up to 13.6 °C at 3 MPa, which should be of great concern for the prevention of coal spontaneous combustion. During the sequestration process of CO2, the adsorption resulted in a decrease in coal surface free energy and then partial conversion to heat, leading to the rise of coal temperature. In addition, the CO2 adsorption on the pore surface caused the expansion and deformation of coal.

Despite the consensus that keeping global temperature rise within 1.5 °C above pre-industrial level by 2100 reduces the chance for climate change to reach the point of no return, the newest Intergovernmental Panel on Climate Change (IPCC) report warns that the existing commitment of greenhouse gas emission reduction is only enough to contain the warming to 3–4 °C by 2100. The harsh reality not only calls for speedier deployment of existing CO2 reduction technologies but demands development of more cost-efficient carbon removal strategies. Here we report an ocean alkalinity-based CO2 sequestration scheme, taking advantage of proton consumption during nitrate assimilation by marine photosynthetic microbes, and the ensuing enhancement of seawater CO2 absorption. Benchtop experiments using a native marine phytoplankton community confirmed pH elevation from ~8.2 to ~10.2 in seawater, within 3–5 days of microbial culture in nitrate-containing media. The alkaline condition was able to sustain at continued nutrient supply but reverted to normalcy (pH ~8.2–8.4) once the biomass was removed. Measurements of δ13C in the dissolved inorganic carbon revealed a significant atmospheric CO2 contribution to the carbonate alkalinity in the experimental seawater, confirming the occurrence of direct carbon dioxide capture from the air. Thermodynamic calculation shows a theoretical carbon removal rate of ~0.13 mol CO2/L seawater, if the seawater pH is allowed to decrease from 10.2 to 8.2. A cost analysis (using a standard bioreactor wastewater treatment plant as a template for CO2 trapping, and a modified moving-bed biofilm reactor for nitrate recycling) indicated that a 1 Mt CO2/year operation is able to perform at a cost of ~$40/tCO2, 2.5–5.5 times cheaper than that offered by any of the currently available direct air capture technologies, and more in line with the price of $25–30/tCO2 suggested for rapid deployment of large-scale CCS systems.