Tomari is a 2,000 MW nuclear power station in Hokkaido, Japan. It is operated by Hokkaido. Based on its capacity (estimated), it can supply roughly 4,505,142 homes (estimated). It ranks #31 of 659 Japan power plants by installed capacity. As a non-combustion source, it has no direct CO₂ emissions from generation. In context, nuclear supplies about 9.1% of Japan's electricity; the national grid averages 477 gCO₂/kWh (32.7% low-carbon) (2025).
Plant data: WRI Global Power Plant Database (CC BY 4.0), id WRI1000674.
Installed capacity (MW), WRI Global Power Plant Database (CC BY 4.0).
Operated by Hokkaido. All plants by this company →
This nuclear plant uses heat from nuclear fission to raise steam for a turbine-generator. It sits in a warm-summer humid continental climate (Köppen Dfb) — Northern Hemisphere, latitude 43.0°N — which shapes how much energy it can produce and how its output varies through the year.
Monthly mean temperature
Heating degree-days here run 77% above the median power plant in this dataset — a proxy for how much extra energy heated equipment must replace through its surfaces in winter.
Climate heat-demand index: 89/100 — this site sits in the top third of the power plants we cover by heating degree-days.
In colder climates, uninsulated hot equipment (boilers, turbines, valves, steam lines) loses proportionally more heat to ambient air — exactly the loss Inzonex modular insulation is designed to cut.
Climate normals: WorldClim 2.1 (1970–2000 monthly normals, 10 arc-min, CC BY 4.0); zone: Köppen-Geiger world climate classification (Kottek et al. 2006, 0.5° grid). Degree-days & heat-demand index computed by PowerAtlas — a modelled heat-demand proxy, not a measured site figure.
The #9 largest nuclear power plant of 16 in Japan by capacity.
Japan has 16 nuclear power plants in this dataset, together about 42,537 MW of capacity.
Coordinates 43.0367, 140.5125 from WRI Global Power Plant Database (CC BY 4.0). View on OpenStreetMap.
