Results and Configurations for the paper "Integrating Geothermal Potential and Hydrogen Imports in PyPSA-Earth: Application to Japan's 2050 Energy System"

Japan is positioning itself as a major global hydrogen importer while simultaneously hosting one of the world’s largest untappedgeothermal resources. Leveraging domestic geothermal energy could reduce import dependency, enhance energy security, andcontribute to a climate-neutral energy system. This study extends the open-source energy system model PyPSA-Earth by integratingspatially explicit Enhanced Geothermal Systems (EGS) potentials and hydrogen import options across 10 aggregated regionalnodes for Japan’s 2050 net-zero transition.Through a co-optimized capacity expansion and dispatch framework, we evaluate the systemic impacts of EGS deployment acrosspower, heating, transport, and hydrogen sectors. Results show that EGS acts as a vital base-load power source, with 35.0 GWeldeployed (271.5 TW h/a, capturing 21.3 % of total power generation). Geothermal deployment concentrated in Kyushu replacesland-intensive variable renewables—avoiding 104 GW of open-field utility PV and 26 GW of onshore wind—and lowers stationarybattery discharge capacity requirements by 70.4 % (-45.3 GW). Although inter-regional AC transmission grid expansion costsescalate to 1.267 billion e/a, net annual system costs decrease by 6.1 % (yielding net annual savings of 4.29 billion e/a).In centralized district heating, direct geothermal heat achieves a dominant 67.3 % share (3.5 TW h/a). Regarding hydrogen supply,maritime imports dominate at 80.4 % under the baseline CIF import target (1.49 AC/kg H2). However, increasing import costs to2.24 AC/kg H2 triggers a sharp structural shift: imports collapse to 1.9 TW h/a, shifting supply to domestic SMR with carbon captureand co-located EGS-electrolysis. These quantitative insights highlight deep geothermal energy as a crucial, land-saving domesticanchor for island energy transitions, while demonstrating new open-source capabilities within PyPSA-Earth.