Thermo-Mechanical Subsurface Energy Storage

Prosjektet har oppnådd flere resultater, som har blitt formidlet på internasjonale konferanser (bl.a. ENuMath, SIAM Geosciences, Gordon Research Conference on Porous Media etc.), såvel som i topp internasjonale tidsskrift. Alle fire PhD studenter finansiert av prosjektet har fullført sine avhandlinger og disputert. De publiserte arbeidene har hovedsakelig omhandlet effektive numeriske løsningsmetoder for koblede ligninger som beskriver deformasjon av- og flyt i bergarter. Videre har prosjektet oppnådd innsikt knyttet til varmeutbredelse og mineralutbredelse forbundet med energilagring, såvel som diverse tilstøtende resultater.

Prosjektet har ført til betydelig kompetanseheving blant deltagerene, og flere nye prosjekter har blitt intiert som utforsker problemstillinger som har blitt synliggjort gjennom prosjektperioden. Prosjektet sine resultater er godt sitert internasjonalt, og har styrket internasjonalt samarbeid i form av økt utveksling på forsker og PhD-nivå.

Intermittent renewable energy (IRE) such as wind and solar are among the fastest growing energy sources, and are critical for the transition to a low carbon emission society. A characteristic feature of these IRE sources is their great variability, on both short (sub-daily) and long (seasonal) time-scales. In contrast, the majority of industrial demand, as well as seasonal household consumption such as heating and cooling, remain fixed or seasonal in nature. We are interested in subsurface energy storage in the context of energy storage in geological permeable layers such as saline aquifers or depleted oil and gas reservoirs. These geological features are found globally, and as such provide an attractive venue for energy storage. Our particular interest lies in thermo-mechanical storage: Hot fluids at temperatures above 50°C are injected at elevated pressure, and both thermal and mechanical energy can be recovered during extraction. To date, large-scale TheMSES has not been applied in the context of IRE. We identify the following key novel challenges associated with TheMSES, which are absent in the state-of-the art from other subsurface flow applications: 1. Cyclical thermo-mechanical weakening of the rock leading to continuous development of fracture networks during operation. 2. High fluid pressure fluctuations and high thermal fluctuations leading to coupled flow-mechanical-chemical systems. 3. Extreme flow-rates needed to accommodate rapid oscillations in the production-demand gap leading to non-equilibrium flow conditions. In this project, we will develop the mathematical tools necessary to address these challenges. Specifically, we will derive models necessary to understand the dominant processes, and develop suitable simulation technology.