International collaboration on research into deep superhot roots of geothermal resources through IEA Geothermal

Abstract

Research into the deep, superhot roots of geothermal systems, which potentially host supercritical fluids, has been actively pursued by several member countries of the International Energy Agency Geothermal Technology Collaboration Program (IEA-Geothermal TCP), including New Zealand, Iceland, USA, Italy and Japan. To date the work has been focused on: a) identification and delineation of superhot geothermal resources that are prospective and accessible by drilling; b) advancing technology to enable reliable energy production from these superhot prospects; and c) a realistic assessment of the potential thermal energy that might be available from these deeper geothermal resources to sustainably support the low carbon energy futures that member countries are all actively pursuing.
Recent advances have seen significant improvements in knowledge of the geochemical and physical conditions to be expected in these superhot settings through experiments in fluid-rock interactions and advanced simulation models. Improvements in deep drilling and well completion technology are also progressing. This paper discusses these aspects, especially from a New Zealand perspective, and summarizes lessons learnt from past superhot geothermal projects, seeking to share knowledge acquired, inform interested parties and direct future enquiry.
In addition, this paper introduces a new collaboration task that was initiated by IEA-Geothermal in 2025. The purpose of the new task is to encourage further collaborative activity to help accelerate novel geothermal energy technology development. Although the focus is on >400°C, the scope is inclusive of >300°C where novel fracture stimulation efforts are informative. Key components will include: a) develop reliable and cost-effective technology that can be used in the superhot energy production infrastructure; b) inform appropriate regulatory regimes and economic frameworks that will provide adequate certainty to support the investment needed; c) construct a shared data repository; and d) promote global testbed activities. The overall goal is to achieve expanding impact by reducing costs and increasing deployment through innovation and demonstration.