| 1. |
- Eliasson Störner, Felicia, 1994, et al.
(författare)
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An improved method for feeding ash model compounds to a bubbling fluidized bed – CLC experiments with ilmenite, methane, and K 2 CO 3
- 2023
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Ingår i: Greenhouse Gases: Science and Technology. - 2152-3878. ; 13:4, s. 546-564
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Tidskriftsartikel (refereegranskat)abstract
- Biomass conversion with carbon capture and storage (Bio-Energy CCS; BECCS) is one of the options considered for mitigating climate change. In this paper, the carbon capture technology chemical-looping combustion (CLC) is examined in which the CO2 is produced in a stream separate from the combustion air. A central research topic for CLC is oxygen carriers; solid metal oxides that provide oxygen for the conversion process. Biomass and waste-derived fuels contain reactive ash compounds, such as potassium, and interactions between the oxygen carrier and the ash species are critical for the lifetime and performance of the oxygen carrier. This work develops and demonstrates an improved method for studying the interactions between ash species and oxygen carriers. The method uses a lab-scale reactor operating under fluidized conditions, simulating CLC batch-wise by switching between feed gas. The novelty of the setup is the integrated system for feeding solid particles of ash model compounds, enabling the simulation of ash species accumulating in the bed. Ilmenite is a benchmark oxygen carrier for solid fuel conversion and was used in this study to evaluate the method using K2CO3 as a model ash compound. Experiments were done at 850 and 950°C. Methane conversion in CLC cycles and fluidization was evaluated with gas analysis and pressure drop measurements. Scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray diffraction (XRD) analysis of bed particles were done after the experiments to establish changes in the morphology and composition of the ilmenite. The method for feeding the ash model compound was concluded to be satisfactory. At 950°C, K accumulated in the particles forming K-titanates and agglomeration was enhanced with K2CO3 addition. The agglomeration mechanism was solid-state sintering between the Fe-oxides forming on the particle surfaces. The bed defluidized at 950°C, but no such effect was seen at 850°C. The method is suitable for studying the Fe-Ti-K system with ilmenite and potassium without the influence of other ash species. © 2023 The Authors. Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley & Sons Ltd.
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| 2. |
- Hildor, Fredrik, 1992, et al.
(författare)
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Metal impregnation on steel converter slag as an oxygen carrier
- 2023
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Ingår i: Greenhouse Gases: Science and Technology. - : Wiley. - 2152-3878. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Oxygen carriers used in chemical looping processes operated with biofuel are affected by the inorganic matter of the fuel. It is therefore expected that the lifetime of the oxygen carrier is limited, and preferably low-cost oxygen carriers should be used. Oxygen carriers based on iron ore or steel manufacturing waste products are available in significant quantities at low cost. However, it is common for these types of materials that their reactivity is low. This study investigates the effect of adding small amounts of more reactive elements into steel converter slag, also called LD slag. Slag particles were wet impregnated with 2 or 5 wt.% of Ni, Cu, Mn, or Ce. The new material’s morphology was evaluated using X-Ray Diffraction and SEM-EDS. Changes in reactivity towards CO, CH4 and the model tar molecule benzene were evaluated using a bench-scale laboratory fluidized bed reactor. It was observed that even small amounts of either Ni, Cu, or Mn could increase reactivity toward CO. Both Cu and Mn formed phases with LD slag that released oxygen via CLOU (chemical looping with oxygen uncoupling) and increased the conversion of methane and benzene. Ni and Ce doping also increased methane conversion but had only a minor effect on the benzene conversion.
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| 3. |
- Iglesias, Rodrigo S., et al.
(författare)
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Carbon capture and geological storage in Brazil : an overview
- 2015
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Ingår i: Greenhouse Gases. - : Wiley-Blackwell. - 2152-3878. ; 5:2, s. 119-130
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Tidskriftsartikel (refereegranskat)abstract
- Brazil is recognized for possessing a low carbon-intensive energy matrix, with most of its power being generated from hydroelectricity. Its greenhouse gas emissions profile is dominated by deforestation and land-use change. Despite this characteristic, the country has been committed to the development of carbon capture and geological storage (CCS) research since this technology started to be recognized as a relevant solution for greenhouse gas emission reductions. This development has gained attention recently owing to the beginning of the production of pre-salt reservoirs, which may contain significant amounts of CO2 in the produced fluids. The work has been carried out mostly through the efforts of the academia and industrial enterprises. This paper presents a summary and a brief description of the recent activities being carried out by these sectors, aiming to develop and promote CCS in Brazil.
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| 4. |
- Iglesias, Rodrigo S., et al.
(författare)
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Characterization and modeling of CO2‐water‐rock interactions in Hygiene Sandstones (Upper Cretaceous), Denver Basin, aimed for carbon dioxide geological storage
- 2018
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Ingår i: Greenhouse Gases. - : Wiley-Blackwell. - 2152-3878. ; 8:4, s. 781-795
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Tidskriftsartikel (refereegranskat)abstract
- Carbon capture and geological storage are among the most valuable technologies capable of reducing CO2 emissions. Long‐term interactions between CO2 and a reservoir, and the integrity of geological formations, are key factors in the selection of adequate reservoirs for permanent storage. Numerical models of CO2‐water‐rock geochemical interactions are often employed to predict the fate of CO2 stored in a reservoir over time. The Hygiene Sandstone, in the Denver Basin, Colorado, USA, is a geological formation with potential for CO2 storage, and was therefore studied in this work, in which we collected and characterized outcrop samples in order to supply the input parameters for numerical simulations. Four representative thin sections of Hygiene Sandstone outcrops were quantified in terms of detrital constituents, diagenesis, and porosity on the basis of conventional petrography. Sandstone mineralogy included, in decreasing order, quartz, K‐feldspar, muscovite, albite, illite, smectite, kaolinite, poikilotopic calcite, and siderite. Porosity ranged from 4% to 13%. A geochemical modeling study of CO2‐water‐rock interactions performed with two characterized samples and brine data from the Hygiene Sandstones, simulating reservoir conditions, suggested that the mineralogy of the sandstone is quite stable under the conditions that were tested and only minor mineralogical and porosity alterations would occur within a thousand years of storage.
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| 5. |
- Johnsson, Filip, 1960
(författare)
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Perspectives on CO2capture and storage
- 2011
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Ingår i: Greenhouse Gases: Science and Technology. - : Wiley. - 2152-3878. ; 1:2, s. 119-133
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Tidskriftsartikel (refereegranskat)abstract
- The last decade has seen a signifi cant increase in the research and development of CO2 capture and storage (CCS) technology. CCS is now considered to be one of the key options for climate change mitigation. This perspective provides a brief summary of the state of the art regarding CCS development and discusses the implications for the further development of CCS, particularly with respect to climate change policy. The aim is to provide general perspectives on CCS, although examples used to illustrate the prospects for CCS are mainly taken from Europe. The rationale for developing CCS should be the over-abundance of fossil fuel reserves (and resources) in a climate change context. However, CCS will only be implemented if society is willing to attach a suffi ciently high price to CO2 emissions. Although arguments have been put forward both in favor and against CCS, the author of this perspective argues that the most important outcome from the successful commercialization of CCS will be that fossil-fuel-dependent economies will fi nd it easier to comply with stringent greenhouse gas (GHG) reduction targets. In contrast, failure to implement CCS will require that the global community agrees almost immediately to start phasing out the use of fossil fuels; such an agreement seems more unrealistic than reaching a global agreement on stringent GHG reductions. Thus, in the near term, it is crucial to initiate demonstration projects, such as those supported by the EU. If this is not done, there is a risk that the introduction of CCS will be signifi cantly delayed. Among the stakeholders in CCS technologies (R&D actors in industry and academia), the year 2020 is typically considered to be the year in which CCS will be commercially available. Considering the lead times for CCS development and the slow pace of implementation of climate policy (post-Copenhagen), the target year of 2020 seems rather optimistic.
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| 6. |
- Joodaki, Saba, et al.
(författare)
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The effect of designing parameter of WAG injection on enhancement of CO2trapping in heterogeneous formations: A numerical study
- 2017
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Ingår i: Greenhouse Gases. - : Wiley. - 2152-3878. ; 7:6, s. 1008-1019
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Tidskriftsartikel (refereegranskat)abstract
- Dissolution and residual trapping of CO2 injected in saline aquifers can be influenced by injection strategies applied. In this study, we focus on the water-alternating-gas (WAG) strategy and investigate the importance of parameters needed to design an effective WAG injection sequence, including (i) CO2 and water injection rates, (ii) WAG ratio, and (iii) number of cycles. Using TOUGH2-ECO2N, we perform 3D numerical simulations of sequences of CO2 and water injection into a heterogeneous formation. Hysteresis in relative permeability and capillary pressure functions is considered based on the Land trapping model. Results show that to design a WAG injection in a high permeable formation, the WAG ratio and number of injection cycles are more important parameters than the CO2 and water injection rates. Increasing the total amount of water injection (i.e., decreasing the WAG ratio for given total amount of injected CO2) improves the CO2 dissolution and residual trapping. It is also shown that increasing the number of injection cycles has a negative effect on both residual and dissolution trapping as measured at the end of the injection sequence, because both the free-phase and the dissolved CO2 plumes in the one-cycle injection scenario reach farther distances and occupy larger reservoir volumes than in the multi-cycle injection. This result means that while water injection following the CO2 injection improves trapping in comparison with the CO2-only injection strategy, the WAG scheme with multiple cycles should not be chosen to enhance trapping for the scenario considered in this study.
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| 7. |
- Purnomo, Victor, 1992, et al.
(författare)
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Interactions between potassium ashes and oxygen carriers based on natural and waste materials at different initial oxidation states
- 2023
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Ingår i: Greenhouse Gases: Science and Technology. - : Wiley. - 2152-3878. ; 13:4, s. 520-534
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Tidskriftsartikel (refereegranskat)abstract
- One of the most essential features of an oxygen carrier is its ability to be oxidized and reduced in order to transfer oxygen in a chemical looping system. A highly reduced oxygen carrier can experience multiple performance issues, such as decreased reactivity, agglomeration, and defluidization. This is crucial for processes that require limited oxygen transfer from the air reactor to the fuel reactor. Meanwhile, biomasses as environmentally friendly fuel options contain ashes, which would inevitably react with oxygen carriers and exacerbate the performance issues. To mimic the interactions between a highly reduced oxygen carrier and biomass ash compounds, four iron-based oxygen carriers, based on natural ores and waste materials, and three potassium salts, K2CO3, KH2PO4, and K2SO4, were investigated in a tubular reactor under an atmosphere consisting of 2.5% H2 and 10% steam in Ar and N2 at 900°C for 3 h. The results from the X-ray diffraction (XRD) material analysis showed that both initially fully oxidized and highly reduced materials reach the same oxidation state after the experiment. Based on the scanning electron microscopy coupled with energy dispersive X-ray spectroscopy results, K from K2CO3 and K2SO4 diffuses in the oxygen carrier particles, while K from KH2PO4 always forms a distinct layer around the particles. The initial oxidation state of an oxygen carrier surface affects the interactions with the potassium salt only to minor extents. Thus, the final state of the material and its performance in a large-scale process are only occasionally and mildly affected by its initial oxidation state.
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| 8. |
- Rasmusson, Kristina, et al.
(författare)
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Distribution of injected CO2 in a stratified saline reservoir accounting for coupled wellbore-reservoir flow
- 2015
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Ingår i: Greenhouse Gases. - : Wiley. - 2152-3878. ; 5:4, s. 419-436
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Tidskriftsartikel (refereegranskat)abstract
- Geological storage in sedimentary basins is considered a viable technology in mitigating atmospheric CO2 emissions. Alternating high and low permeability strata are common in these basins. The distribution of injected CO2 among such layers affects e.g. CO2 storage efficiency, capacity and plume footprint. A numerical study on the distribution of injected CO2 into a multi-layered reservoir, accounting for coupled wellbore-reservoir flow, was carried out using the T2Well/ECO2N code. A site-specific case as well as a more general case were considered. Properties and processes governing the distribution of sequestrated CO2 were identified and the potential to operationally modify the distribution was investigated. The distribution of CO2 was seen to differ from that of injected water, i.e. it was not proportional to the transmissivity of the layers. The results indicate that caution should be taken when performing numerical simulations of CO2 injection into layered formations. Ignoring coupled wellbore-reservoir flow and instead adopting a simple boundary condition at the injection well, such as an inflow rate proportional to the transmissivity of each layer, may result in significant underestimation of the proportion of CO2 ending up in the shallower layers, as not all relevant processes are accounted for. This discrepancy has been thoroughly investigated and quantified for several CO2 sequestration scenarios.
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| 9. |
- Rasmusson, Kristina, et al.
(författare)
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Exploring residual CO2 trapping in Heletz sandstone using pore-network modeling and a realistic pore-space topology obtained from a micro-CT scan
- 2021
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Ingår i: Greenhouse Gases. - : John Wiley & Sons. - 2152-3878. ; 11:5, s. 907-923
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Tidskriftsartikel (refereegranskat)abstract
- Geological storage of CO2 in deep saline aquifers mitigates atmospheric emissions. In situ storage is facilitated by several trapping mechanisms including residual trapping, which plays a major role in the containment of CO2. Understanding the underlying mechanisms of residual trapping is crucial for planning storage projects. Of special interest is the relationship between the initial and residual CO2 saturations-the so-called IR curve, needed for predictive macroscopic-scale simulations. This study aims to improve the understanding of residual trapping in sandstone from the Heletz site, where extensive field experiments have been performed, by using 3D-image analysis on core sample CT-data. This was done to gain knowledge on physical properties (such as radius, coordination number, aspect ratio, shape factor of pores, and pore connectivity) of importance to residual CO2 trapping. Pore-network flow modeling on a network representation, with the extracted pore-space topology, was employed to estimate the IR curve. The core sample exhibited pores with a large range of coordination numbers, a mean aspect ratio of 1.4, and shape factors mostly corresponding to triangular cross-sections. The estimated IR curve was monotonic, fitting an Aissaoui-type trapping model, displaying a lower sensitivity to the advancing contact angle than previously thought, and indicating a good ability to residually trap CO2. This study provides the first report of values for the three above mentioned properties for Heletz sandstone, and the first estimate of an IR curve for CO2/brine in Heletz sandstone based on pore-network modeling on a network with a topology retrieved from a core-sample CT-scan. (c) 2021 Society of Chemical Industry and John Wiley & Sons, Ltd.
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| 10. |
- Rasmusson, Maria, et al.
(författare)
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The impact of co-contaminant SO2, versus salinity and thermodynamic conditions, on residual CO2 trapping during geological storage
- 2018
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Ingår i: Greenhouse Gases. - : WILEY PERIODICALS, INC. - 2152-3878. ; 8:6, s. 1053-1065
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Tidskriftsartikel (refereegranskat)abstract
- During geological storage in deep saline aquifers, immobilization of CO2 in reservoir rock determines both storage safety and capacity. Assessment of the sensitivity of residual trapping to different parameters (interfacial tension and contact angles) and the storage conditions affecting these is therefore of great importance. One aspect of concern is the presence of co-contaminants such as SO2 in the injected gas. Using experimentally measured values of interfacial tensions and contact angles, we apply pore-network modelling (which accounts for pore-scale mechanisms such as snap-off, cooperative pore body filling and piston-type displacement) to a generic sandstone network to quantify the impact of SO2 co-injection on residual CO2 trapping, and its relative importance as compared to the influences of thermodynamic conditions and salinity. We show that the presence of small amounts of SO2 in the injected CO2 has a notable positive effect on the amount of CO2 becoming residually trapped (similar to 3% increase at 1 wt% SO2). However, this effect is small compared to that of the brine salinity (similar to 20% decrease in residually trapped CO2 over the salinity range 0.2 to 5 M NaCl). Still, co-injection of SO2 could potentially favour the residual trapping of CO2 in reservoir rocks, especially at storage sites with inclined aquifers where the CO2 is set to migrate hydro-dynamically over long distances. The salinity of the resident brine is of primary importance during storage site selection. Furthermore, sensitivity analysis shows that the advancing contact angle strongly impacts residual CO2 trapping.
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