Geothermal energy is a clean resource that underpins a decarbonised EU energy system. Both geothermal productivity and sustainability rely on connected subsurface fracture systems, so it is critical to understand how injection-induced fracture behaviour influences the reservoir circulation, thermal longevity and seismic hazards of geothermal systems. This project is an integrated geomechanical, hydrological and seismological investigation of the fundamental physics of injection-induced fracture and flow behaviour and permeability evolution in fractured hot rocks. The project aims to advance sustainable geothermal exploitation and enhance seismic hazard management to support unlocking the huge potential of geothermal deployment in the Netherlands.

• dr. André Niemeijer
• Laurens Kleijbeuker MSc
• Jing Li
• dr. Mark Jefferd

• Loes Buijze

A large number of coal mines in Europe are planning mine closure and a just post-closure transition. GeoSolar aims to repurpose end-of-life coal mines as huge thermal batteries for low-carbon, high-temperature district heating, making use of mine land for solar energy installations and mine workings and goaf for thermal energy storage. This project will develop innovative coupled mine water thermal and solar energy storage systems integrated with local district heat networks. Coupled multiphysics modelling of mine water flow and heat storage dynamics will be performed to evaluate the operability and efficiency of the coupled energy storage system during seasonal mine water thermal energy storage and recovery. The deployment of the proposed system is anticipated to achieve widespread societal benefits and social impact, in terms of green energy production, decarbonisation potential, economic growth, and green job creation. The proposed system is also projected to have a huge potential for efficient uptake at European end-of-life and abandoned coal mines.

• dr. André Niemeijer

Green hydrogen will play a pivotal role in future energy systems, requiring large-scale underground storage in porous geological formations. Depleted offshore and neighbouring onshore gas fields represent promising candidates for such storage in the Netherlands. Building upon extensive experience from geological carbon storage, this project aims to identify suitable storage sites and advance the understanding of large-scale hydrogen storage in subsurface formations. This project will investigate hydrogen flow and mixing dynamics, geochemical reactions, and geomechanical behaviour in fractured porous media. Particular emphasis will be placed on how the coupled interactions among these processes, together with cyclic hydrogen injection and withdrawal, influence caprock integrity, fault re-activation, and fluid-rock interactions. The outcomes will support the identification of optimal storage sites and the development of safe and efficient operational strategies for hydrogen storage in porous geological formations.

• Zijia Zhu
• dr. Suzanne Hangx
• prof. dr. Liviu Matenco