Lined rock caverns:A hydrogen storage solution

The inherent intermittency of renewable energy sources frequently leads to variable power outputs, challenging the reliability of our power supply. An evolving approach to mitigate these inconsistencies is the conversion of excess energy into hydrogen. Yet, the pursuit of safe and efficient hydrogen storage methods endures. In this perspective paper, we conduct a comprehensive evaluation of the potential of lined rock caverns (LRCs) for hydrogen storage. We provide a detailed exploration of all system components and their associated challenges. While LRCs have demonstrated effectiveness in storing various materials, their suitability for hydrogen storage remains a largely uncharted territory. Drawing from empirical data and practical applications, we delineate the unique challenges entailed in employing LRCs for hydrogen storage. Additionally, we identify promising avenues for advancement and underscore crucial research directions to unlock the full potential of LRCs in hydrogen storage applications. The foundational infrastructure and associated risks of large-scale hydrogen storage within LRCs necessitate thorough examination. This work not only highlights challenges but also prospects, with the aim of accelerating the realization of this innovative storage technology on a practical, field-scale level.</p

Injection of CO2-saturated brine in geological reservoir: a way to enhanced storage safety

Injection of free-phase supercritical CO2 into deep geological reservoirs is associated with risk of considerable return flows towards the land surface due to the buoyancy of CO2, which is lighter than the resident brine in the reservoir. Such upward movements can be avoided if CO2 is injected in the dissolved phase (CO2aq). In this work, injection of CO2-saturated brine in a subsurface carbonate reservoir was modelled. Physical and geochemical interactions of injected low-pH CO2-saturated brine with the carbonate minerals (calcite, dolomite and siderite) were investigated in the reactive transport modelling. CO2-saturated brine, being low in pH, showed high reactivity with the reservoir minerals, resulting in a significant mineral dissolution and CO2 conversion in reactions. Over the injection period of 10 yr, up to 16% of the injected CO2 was found consumed in geochemical reactions. Sorption included in the transport analysis resulted in additional quantities of CO2 mass stored. However, for the considered carbonate minerals, the consumption of injected CO2aq was found mainly in the form of ionic trapping.Peer ReviewedPostprint (author's final draft

Artificial Neural Network-Based Caprock Structural Reliability Analysis for CO2 Injection Site—An Example from Northern North Sea

publishedVersio

Insights into past tectonism from authigenic quartz

Authigenic quartz grains carry information that is diagnostic for the thermal history and thereby the burial depth and uplift of sediments. Recycled quartz grains with embayed or rounded authigenic remnants have been observed globally, but the value of these grains in unravelling past tectonism is presently underexplored. In this study, we launch a new method to demonstrate that cathodoluminescence (CL) in combination with fluid inclusion data and textural characteristics of authigenic quartz can provide important information about past tectonic activity. Vital in the method is the realisation that recycled quartz grains can be distinguished from other quartz grains by their geochemical CL fingerprint, allowing tracking of uplifted source terrains in a direction towards higher fractions of the recycled grains. Furthermore, regional mapping can reveal both intra-basinal recycling as well as recycled grains transported into the basin from external sources. The new proposed method is simple and does not require more than a standard Scanning Electron Microscope equipped with a CL detector, available at many geoscientific institutions worldwide. This innovative approach applies to a wide section of geoscientific disciplines, and complement and supplement other conventional methods used for unravelling past tectonism.publishedVersio

Injection of CO2-saturated brine in geological reservoir: a way to enhanced storage safety

Injection of free-phase supercritical CO2 into deep geological reservoirs is associated with risk of considerable return flows towards the land surface due to the buoyancy of CO2, which is lighter than the resident brine in the reservoir. Such upward movements can be avoided if CO2 is injected in the dissolved phase (CO2aq). In this work, injection of CO2-saturated brine in a subsurface carbonate reservoir was modelled. Physical and geochemical interactions of injected low-pH CO2-saturated brine with the carbonate minerals (calcite, dolomite and siderite) were investigated in the reactive transport modelling. CO2-saturated brine, being low in pH, showed high reactivity with the reservoir minerals, resulting in a significant mineral dissolution and CO2 conversion in reactions. Over the injection period of 10 yr, up to 16% of the injected CO2 was found consumed in geochemical reactions. Sorption included in the transport analysis resulted in additional quantities of CO2 mass stored. However, for the considered carbonate minerals, the consumption of injected CO2aq was found mainly in the form of ionic trapping

Constraints on natural global atmospheric CO2 fluxes from 1860 to 2010 using a simplified explicit forward model

Land-use changes until the beginning of the 20th century made the terrestrial biosphere a net source of atmospheric carbon. Later, burning of fossil fuel surpassed land use changes as the major anthropogenic source of carbon. The terrestrial biosphere is at present suggested to be a carbon sink, but the distribution of excess anthropogenic carbon to the ocean and biosphere sinks is highly uncertain. Our modeling suggest that land-use changes can be tracked quite well by the carbon isotopes until mid-20th century, whereas burning of fossil fuel dominates the present-day observed changes in the isotope signature. The modeling indicates that the global carbon isotope fractionation has not changed significantly during the last 150 years. Furthermore, increased uptake of carbon by the ocean and increasing temperatures does not yet appear to have resulted in increasing the global gross ocean-to-atmosphere carbon fluxes. This may however change in the future when the excess carbon will emerge in the ocean upwelling zones, possibly reducing the net-uptake of carbon compared to the present-day ocean

Interactions between CO2, saline water and minerals during geological storage of CO2

This doctoral thesis is based on the following papers: Paper A: Hellevang, H., Aagaard, P., Oelkers, E.H., and Kvamme, B., 2005. Can dawsonite permanently trap CO2? Environmental Science and Technology, 39, 8281-8287. Paper B: Hellevang, H., Kvamme, B., and Aagaard, P., 2004. Long term interactions between minerals and reactive fluids - Stability of dawsonite. In Proceedings of the Third Annual Conference on Carbon Capture and Sequestration DOE/NETL, Alexandria, VA, May 3-6, 1-7 Paper C: Hellevang, H., and Kvamme, B. CO2-water-rock interactions - ACCRETE simulations of geological storage of CO2. Submitted to Applied Geochemistry. Paper D: Hellevang, H., Kumar, S., Fladmark, G., and Kvamme, B. CO2 storage in the Utsira Formation – ATHENA 3D reactive transport simulations. Submitted to Basin Research. Paper E: Hellevang, H., and Kvamme, B. 2006. ACCRETE – Geochemistry solver for CO2-water-rock interactions. Paper submitted to GHGT8, Trondheim, June 19-22, 2006. Paper F: Khattri, S.K., Hellevang, H., Fladmark, G.E., and Kvamme, B. 2006. Deposition of Green House Gases by Compositional Simulator: Long Term Reactive Transport of CO2 in the Sand of Utsira. Submitted to Transport in Porous Media

Fluid‐Rock Interactions in Clay‐Rich Seals: Impact on Transport and Mechanical Properties

Fluid‐rock interaction in low‐permeable clay‐rich seal units is an important topic for the evaluation of the long‐term seal integrity during geological storage of CO2. In low‐permeable sealing units, the diffusion of CO2 into the matrix is a slow process, and studies of CO2‐initiated fluid‐rock interaction in seals are challenging. In this paper, we present an overview of CO2 transport mechanism and fluid‐rock interaction processes that might alter mechanical and transport properties of seals. The review includes theoretical considerations and simulations, experimentally demonstrated processes, and field examples of flow and fluid‐rock interaction in intact clay‐rich seals as well as for fractures. For clay‐rich seals dominated by minerals like quartz, illite, and smectite, the reactivity due to drop in pH is found to be low, and most reaction observed is found to involve calcite. Only minor porosity changes are observed, and implications for flow and CO2 transport are uncertain due to limited data available. Swelling and shrinking property of smectites due to CO2 sorption and CO2 alterations within fractures in clay‐rich seal is hardly addressed in the literature.Fluid‐Rock Interactions in Clay‐Rich Seals: Impact on Transport and Mechanical PropertiesacceptedVersio

Estimation of Mutual Solubility of Co2-H2o in Saline Aquifer Systems Using Epc-Saft Equation of State

A primary assessment of mutual solubility of CO2 and water for estimated max and min temperatures and pressures of the prospective reservoir formations of Aurora; Cook (at >2650 m depth) and Johansen (at >2700 m depth) have been done using ePC-SAFT equation of estate. Mole fraction of CO2 in H2O ranges from 0.025 to 0.027, and H2O in CO2 form 0.016 to 0.023 over pressure-temperature ranges of 265 – 283 bar and 95 – 110 °C. The potential for drying out effects (H2O to CO2) is significant, and there would be risk of salt precipitation in the near well area.publishedVersio