The objective of the H2STORE ("hydrogen to store") project is to investigate the feasibility of storing hydrogen produced from excessive wind and solar power in porous geological formations as well as the investigation of in-situ methane generation processes. H2STORE is a three-year, joint research project of the universities Jena and Clausthal and the national research centers GFZ, Potsdam in Germany and CNRS, Nancy in France started in 2012. The project is supported by international industrial partners and funded by the German national research program on "energy storage".

So far, several studies on H2 storage in salt caverns have been published and pilot projects are already established (e.g. in the U.S. and U.K.). Hydrogen storage in porous geological formations, however, has received only limited attention in the past. In contrast to salt caverns, porous formations could potentially provide very high storage capacities. Several concerns like the high hydrogen diffusivity have to be investigated as well as the potential reactions of injected hydrogen, formation fluids, and the storage complex. The aim of the project is to evaluate the feasibility of hydrogen storage in converted gas fields by comprehensive investigation of geo-hydraulic, mineralogical, geochemical and biological processes, gas mixing processes, caprock integrity and fluid transport properties of the reservoir rocks during the storage of hydrogen in porous rock formations.

The hydrogen impact on fundamental reservoir properties and mineralogy will be investigated experimentally as well as geochemical and gaseous phase mixing numerical simulations are included in the project activities of H2STORE. Industrial partners will provide site-specific rock material and experimental facilities for treatment of the samples under reservoir conditions have been designed and built as part of the research program.

The experimental results will be included in numerical reservoir simulation work comprising:

(a) Modeling of hydrogen propagation in the subsurface reservoir formation supplemented by its mixing with the residual gases, (b) Simulation of the geochemical reactions of gas mixtures with rock minerals, organic substances and formation water, and (c) Modeling of coupling of bio-dynamic processes and the processes of reactive transport in porous media. The simulations shall enable the transfer of experimental results from the laboratory to the field-scale and help formulating requirements on hydrogen storage in converted gas fields.

An overview on the concept, objectives and goals of the collaborative work will be presented, which may serve as an impulse for ongoing investigations on hydrogen and energy storage in porous underground rocks.

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