Geological energy storage in Aotearoa New Zealand a technical, geological and social overview

Aotearoa New Zealand is transitioning to a low emissions economy with an aspirational target of 100% renewable electricity production by 2030. The renewable energy sources that are increasingly relied upon bring with them challenges relating to intermittency of supply over the short term as well as over the medium to long term (as a result of varying rainfall impacting hydro generation). Long-term and high-capacity energy storage solutions are therefore critical to the government’s Just Transitions renewable energy strategy. Geological Energy Storage (GES) is a potential solution for Aotearoa New Zealand’s energy storage needs. The geological subsurface is an efficient long-term and high-capacity energy storage medium for compressed gas or fluids which can be stored and later decompressed and used to regenerate energy. GES has been proven to be feasible in natural and manmade underground voids (i.e. salt caves, mine shafts, tunnels, and boreholes), and in subsurface pore spaces (i.e. saline aquifers and depleted gas and oil reservoirs) where the highest storage potential is found. This work provides a high-level overview of technical, geological, and social aspects of this alternative energy storage solution, focusing on the Taranaki region and the Just Transitions energy action plan as it may be implemented there.