Numappara is a 675 MW hydro power station in Tochigi, Japan. It is operated by EPDC. Based on its capacity (estimated), it can supply roughly 676k homes (estimated). It ranks #128 of 692 Japan power plants by installed capacity. Commissioned in 1973, it is around 53 years old — an older, legacy facility. As a non-combustion source, it has no direct CO₂ emissions from generation. In context, hydro supplies about 7.2% 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 WRI1000726.
Known, modelled and calculated values are kept separate. Missing fields are shown as unavailable.
The capacity and/or fuel fields on this page include a source-backed provenance label from GEM, an official registry, Wikidata, OSM, or a cross-source match.
capacity: GEM tracker 2026 (location L100000602279); fuel: WRI source-record fuel
At 675 MW, Numappara is well above the median hydro plant in Japan (350 MW). Technically it is described as pumped storage. Hydropower converts the energy of falling or flowing water into electricity; output depends on rainfall and reservoir level, and large dams also provide grid balancing and storage.
Capacity comparison computed from the WRI Global Power Plant Database; fuel-type context is general engineering background.
Installed capacity (MW), WRI Global Power Plant Database (CC BY 4.0).
Operated by EPDC. All plants by this company →
This hydro plant converts the energy of falling or flowing water through hydro turbines. It sits in a warm-summer humid continental climate (Köppen Dfb) — Northern Hemisphere, latitude 37.1°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 52% 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: 80/100 — this site sits in the top third of the power plants we cover by heating degree-days.
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.
For a plant’s outdoor hardware — heat-recovery steam generators (HRSG), expansion joints, valves, flanges and their insulation — the local climate sets how fast unprotected steel and coatings degrade. This site sits in a moderately corrosive environment (estimated ISO 9223 class C3 — Medium), with humidity / wetness the leading environmental stress.
Higher environmental severity is exactly where protective removable insulation pays back most: a sheltered micro-climate slows corrosion, UV and thermal-cycling damage and extends outdoor hardware service life. This is an indicative site-climate context — not a condition assessment of any specific plant or operator.
Indicative estimate via the ISO 9223:2012 informative method (atmospheric corrosivity from temperature, time-of-wetness and airborne salinity), using WorldClim climate normals, the Köppen-Geiger class and coast distance. Indicative, not a measured corrosion rate.
The #16 largest hydro power plant of 55 in Japan by capacity.
Japan has 55 hydro power plants in this dataset, together about 27,749 MW of capacity.
Coordinates 37.0938, 139.9116 from WRI Global Power Plant Database (CC BY 4.0). View on OpenStreetMap.
Numappara is a 675 MW source-record hydro power plant in Tochigi, Japan, commissioned in 1973.
Its output is enough to supply roughly 675,771 homes (estimated).
Numappara is operated by EPDC.
