A safe and efficient hydrogen storage mechanism will be crucial for the successful transition towards a green hydrogen economy. Underground storage of hydrogen can be a viable option for short to long-term storage to meet the fluctuations in energy demand. However, there is limited understanding of the pore-scale displacement and trapping mechanisms for hydrogen-brine systems, especially in...
The goal of reducing carbon emissions relies heavily on the world’s energy sectors to undergo significant energy transformations. The hydrogen economy plays a critical role in achieving that goal by harvesting hydrogen and using it as an energy carrier. The current storage options limit hydrogen's large-scale adaptation to a major energy form. For that reason, underground hydrogen storage has...
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The success of large-scale geological storage of gases requires proper understanding of the interfacial behavior among the participating phase. In this work a systematic study on the impact of pressure and brine salinity on the interfacial tension (IFT) of binary H2-brine systems as well as wettability within ternary systems comprising H2-brine-shale are investigated....
The decarbonization of energy mainly requires the substitution of fossil fuels with low-carbon alternatives. Heavy industries require high-temperature heat that cannot be supplied through electricity. Moreover, the production of renewable electricity requires a storage medium to compensate for their intermittent behaviour. Hydrogen is a favorable medium for storing the excess low-carbon...
Hydrogen is considered a low-carbon fuel that can potentially contribute to the large-scale decarbonization of different sectors, including power generation, heating, transportation, and industry. Blending hydrogen into national gas distribution networks can also help decarbonize distributed carbon emissions from domestic consumers where carbon capture is not feasible. More pilot projects...
Gas injection and withdrawal in the subsurface can be considered as a long-term energy storage solution. Green gas can be produced from the excess electricity during peak production and can subsequently be injected into the surface reservoir and withdrawn during times of high demand. Repeated injection and withdrawal of gas causes capillary pressure hysteresis – in this work we use X-ray...
Underground hydrogen storage (UHS) in porous media offers a long-term and large-scale storage solution which is vital for a sustainable H2 economy. Despite growing interest in the topic, the understanding of the physical processes during cyclic H2 flow is not yet adequate. Here we use microfluidics to experimentally investigate multiple cycles of H2 injection and withdrawal under a range of...
The bulk of renewable energy production varies in a way that typically does not align with time-dependent energy consumption. This can lead to an energy surplus or a shortage of the energy supply causing a challenge in supporting the baseload requirements. Enormous storage capacity is required to accommodate these fluctuations in supply and enable large-scale storage of excess renewable...
Over the last years the interest in molecular hydrogen (H2) has soared: in many countries an accelarating energy transition is considering hydrogen as the main energy carrier of the future. To enable large scale storage for hydrogen, research on subsurface storage options in geologic structures as artificially created caverns in evaporites (e.g. salt domes) or depleted gas fields mainly in...
Geological porous reservoirs are seen as an attractive solution for large scale underground hydrogen storage (UHS). Microbes are expected to be abundant in these reservoirs and could have a significant impact on the UHS process as the stored hydrogen can be used in their metabolism. Next to adverse effects such as hydrogen loss, H2S formation and clogging, microbial activity could alter the...
We use high-resolution three-dimensional X-ray imaging to study hydrogen injection and withdrawal in the pore space of Bentheimer sandstone. The results are compared with a replicate experiment using nitrogen. We observe less trapping with hydrogen because the initial saturation after drainage is lower due to channelling. Remarkably we observe that after imbibition, if the sample is imaged...
Numerical modelling with commercial software (CMG) was used to analyse of the effect of contrasting permeabilities on fluid flow and hydrogen plume development in subsurface, porous media employed in underground hydrogen storage. Increasing heterogeneities were introduced to reservoir-scale simulations, based upon the Navajo sandstone, Utah in an aquifer-supported system. Initial...
As a strategy to match renewable energy supply and demand, surplus energy can be converted into hydrogen gas and stored in the pore space of geological subsurface formations such as saline aquifers and depleted gas reservoirs. Although similar operations with natural gas and CO2 are well studied, H2 has unique chemical and physical properties which, combined with cyclic injection and...
Hydrogen for clean energy is in the national and international spotlight. Offshore wind presents an extensive renewable energy source in the UK, and a large green hydrogen resource, positioning the UK to be a major player in the emerging global hydrogen market. In the UK and around the globe there’s a handful of likely subsurface hydrogen storage sites and it is widely recognised that hydrogen...
To meet the global commitments for net zero carbon emissions our energy mix must transition away from fossil fuels. Hydrogen is gaining increasing recognition as a low carbon energy option to support this energy transition, tackling the hard to abate sectors such as decarbonising domestic and industrial heat, power generation and heavy-duty transport. It can also promote increased renewable...
The characterisation of multiphase flow properties is key to predict large-scale fluid behaviour in the subsurface, such as the migration of a carbon dioxide (CO2) plume at a Carbon Capture and Storage (CCS) site. Many CCS sites have displayed unexpected fluid flow behaviour, where the CO2, once injected, migrated away from injection wells at significantly higher rates and in different...
In sequestered CO2 underground wells or in permanently abandoned wells, a cement plug is typically used as a well barrier material to ensure long-term zonal isolation of the well [1]. Proper plugging should prevent any flow of fluids from the well to the surrounding environment and the surface. It is assumed that the ability of the cement plug to fulfil its barrier function over the long term...
Carbon capture and storage (CCS) is a key technology to reduce CO2 emissions and reach long term climate goals, aiming to limit the temperature rise to 1.5 ◦C above pre-industrial levels. CCS consists of capturing CO2 from large industrial processes or from burning fossil fuels in power generation. The captured CO2 is thereafter transported via pipelines or ships and stored in appropriate...
Expansion and compression of fluids by injection or production in the reservoir leads to cooling or heating effects due Joule-Thomson and adiabatic processes. This effect on the near-wellbore temperature becomes significant in some applications such as carbon dioxide storage in a depleted gas reservoir. Commercial reservoir simulators using a compositional approach can model these effects....
After $\text{CO}_2$ is sequestrated into deep saline aquifers, it dissolves into underlaying brine. In presence of $\text{Ca}^{2+}$, extensive precipitation reaction may emerge. However, how precipitation reactions impact $\text{CO}_2$ dissolution kinetics is still an open question that affects the evaluation of sequestration safety and efficiency. Three mechanisms are possible: (1) suspended...
CO$_2$ storage at climate-relevant scales will involve rapid deployment of projects worldwide in diverse geological settings, with each involving several millions of tons injection per annum. CO$_2$ transport also can be varied, with pipeline transport being supplemented by direct injection from ship or other land-based transport. Successful projects should have low risk of injectivity loss to...
One of the toxic greenhouse gases that significantly alters the climate is CO2, and it may be possible to lower its emission by sequestering it in an appropriate geological subsurface formation. For a secure and effective sequestration, it is necessary to answer questions relating to enhancing the reaction rates of rock minerals to speed up sequestration, understanding the critical reservoir...
Geological heterogeneities impact the timescale and distribution of capillary trapping of CO$_2$ in aquifers [1,2]. Natural capillary pressure barriers trap the non-wetting phase at saturations greater than expected from pore-scale residual trapping processes alone, potentially providing greater CO$_2$ storage capacity. Capillary heterogeneity trapping has the potential to significantly...
In geological storage of carbon dioxide (CO2), CO2 captured from large emission sources, such as thermal power plants, is injected into the brine-saturated reservoir under a supercritical condition with a density of 600-700 kg/m3. One of the primary concerns in geological storage is the leakage of CO2 due to buoyancy force. The dissolution of CO2 into formation brine improves CO2 storage...
Permanent CO2 storage in basalts by means of mineralisation is a promising cost-effective way to achieving reduction of carbon emissions in view of climate change mitigation. CO2 is dissolved in water before injection in the subsurface, resulting in increased trapping safety, since solubility has already taken place. Storage of dissolved CO2 in basalts at shallow depth has additional...
Storing CO2 in the depleted North Sea chalk reservoirs represents a potentially attractive and cost-effective way to reduce the environmental consequences of emissions of CO2. In this study we present a comprehensive investigation of CO2 injection in chalk under different in-situ conditions which includes characterization of 1) the response of chalk to CO2 injection in the short and long...
In wells for carbon capture and storage (CCS), fractures can develop in the cement due to strong thermal shocks upon pressurized CO2 injection into the subsurface. The network of these fractures forms leakage pathways that can impair well integrity, and thus impede successful geological storage of CO2. In this study, we investigate how thermal shocks affect cement integrity under unconfined...
Sequestration of captured CO2 in geological formations to reduce its content in the atmosphere is one proposed solution to mitigate global warming. This solution, generally referred as carbon geo-sequestration (CGS), involves the injection of CO2 into depleted reservoir or saline aquifers. The success of CGS relies on many technical aspects, including CO2 plumes extension, gravity segregation,...
Most CO2 geological storage sites, such as saline formations and depleted hydrocarbon reservoirs, rely on structural trapping provided by the caprock and fault gouge material as one of the trapping mechanisms. Clay- and quartz-rich caprocks are expected to be water-wet at reservoir conditions and create a positive capillary pressure to ensure CO2 trapping. However, most...
Capillary trapping (also known as “residual trapping”) of supercritical carbon dioxide (‘‘scCO$_2$’’) is a key mechanism contributing to the safety and security of geologic sequestration operations for carbon capture and storage (CCS). Recent experimental studies have suggested that cycles of scCO$_2$ and brine injections alter surfaces of sandstone grains and increase capillary trapping. We...
One of the most important trapping mechanisms in CO2 geologic storage is convective dissolution. When CO2 is dissolved, it slightly increases the brine density, resulting in natural convection in the form of dense fingers. In most previous studies, natural groundwater flow and the associated hydrodynamic dispersion were neglected. In this work, we study the effect of hydrodynamic dispersion...
CO$_2$ sequestration and storage in deep saline aquifers is a promising technology for mitigation of the excessive concentration of the greenhouse gas in the atmosphere. The assessment of the CO$_2$ plume migration depends on the complex multi-physics-based numerical simulation approaches which require prohibitively high computational costs due to the highly non-linear coupled governing...
Geothermal fluids tend to contain large quantities of dissolved gasses such as CO2 and N2. A drop in pressure towards the production well means that free gas bubbles can form as the solubility limits can be exceeded. These bubbles occupy part of the pore space thereby leading to a decrease of the water relative permeability, thus leading to reduced production of geothermal waters. In addition,...
Geological carbon dioxide (CO2) sequestration is considered as a technology for reducing the atmospheric content of CO2 [1, 2]. CO2 has been widely injected into saline aquifers or oil reservoirs for sequestration in recent decades [3]. This process involves displacing resident fluids from porous media, which is unstable due to the unfavorable mobility ratio between the resident and injected...
Subsurface carbon-dioxide (CO$_2$) and hydrogen (H$_2$) storage are considered a promising approach to reduce the greenhouse gas emissions of large polluters like the steel, chemical and cement industries. In order to develop gas storage techniques in geological formations it is crucial that we can describe and monitor the associated multiphase flows. Micro computed tomography (Micro CT, X-ray...
Geological storage of CO2 is currently considered as the most promising large-scale option to avoid emissions by industrial activities. As suitable subsurface containers, oil and gas reservoirs and the more abundant saline aquifers are considered. The injection of dry or under-saturated supercritical CO2 into water-bearing formations leads to the formation of a dry-out zone due to...
Mudstones and shales are commonly the primary control on the sealing efficiency for subsurface storage applications (e.g. energy, CO2, H2, waste). However, their fine-grained and heterogeneous nature makes their full characterisation highly challenging. Here we demonstrate the multi-scale and dynamic imaging approaches that can help meet these challenges and discuss limitations and future...
CO2 geologic sequestration in deep saline aquifers and depleted oil reservoirs is an effective option for large-scale and long-term carbon mitigation to address global climate challenges.[1] After being injected into the target geological formations with a low permeability caprock above them (structural trapping), CO2 is stored by trapping in the pores (residual trapping), dissolving in the...
Carbon storage (CS) in geological formations is a promising technology for mitigating climate change (IPCC, 2021). Historically, sandstone have been targeted for CS, but in the specific case of Denmark, chalk represents a more promising storage medium as it has a much higher storage potential (Bonto et al., 2021). Chalk, however, has a much higher reactivity with CO$_2$-saturated brines than...
Atmospheric CO2 concentrations are expected to double over the next three decades, and reducing its emissions alone will not be enough to reduce greenhouse gas emissions and limit anthropogenic warming. The removal of large quantities of CO2 from the atmosphere or the prevention of newly produced CO2 from reaching the atmosphere is possible through the combination of carbon mineralization in...
Particulate flow in porous materials is a common phenomenon and also one of the big challenges in flow dynamics. As one example, fines migration within porous rocks may block the pores and reduce the permeability, leading to formation damage in subsurface reservoirs. Varied physical and chemical parameters causing fines migration have been widely studied in many subsurface applications such as...
A significant part of the overall energy consumption is related to the provision of heat – for heating of buildings and tap water as well as for industrial processes (e.g. around 54% for Germany in 2010-2020 [1]). Considering this as well as the fact that this thermal energy is still mainly provided using fossil fuels (above 70% for Germany in 2020 [1]), energy transition is also a transition...
Due to a mismatch in energy production and energy demand a loss free method of storing energy is required. One class of materials suitable for this are salt hydrates. Salt hydrates release energy in the form of heat when subjected to water vapor by incorporating this water inside the crystal lattice (hydration/discharging). When subjecting the hydrated material to heat water is removed from...
Society is focusing progressively on the introduction of renewable energy systems to replace fossil fuels which can play a major role in reducing CO2 emissions [1]. Connected to these renewable alternatives is the intermittent character. Solar energy, as a pollution-free, inexhaustible, and affordable energy resource has vast potential [2]. However, one of the barriers for solar energy...
Solar-driven thermochemical fuel processing has shown potential for efficient large-scale solar fuel production due to its broadband solar absorption and favorable thermodynamics and kinetics at high operating temperatures. The porous media is one of the crucial components in the fuel production reactor, which directly converts concentrated solar radiation into heat, enhances heat and mass...
Simulations of two-phase flow in porous media are of interest in a wide range of fields such as groundwater remediation, oil and gas extraction, and hydrogen storage devices [1–5]. In the field of hydrogen storage, the flow of gases and liquids in porous media layers of fuel cells greatly impact their performance [6]. Historically, continuum models have been the most prominent as they are...
In this work, the impact of clay minerals on formation damage of sandstone reservoirs is studied to provide a better understanding of the problem of deep geothermal reservoir permeability reduction due to fine particle dispersion and migration. In some situations, despite the presence of filters in the geothermal loop at the surface, particles smaller than the filter size (<1 µm) may...
Geothermal systems in crystalline basement rocks require fractures and faults to allow economic heat production. Sufficient permeability of these flow paths is vital and affects the lifetime of such systems. As fluids are produced and reinjected, the resulting flow, fluid mixing as well as related pressure and temperature changes affect the geochemical equilibria between fluids and host rock....
