Hydro power plant in Waikato, New Zealand. Approximate location -38.0714, 175.6433.
HydroWaikatoNew Zealand
Arapuni is a 192 MW hydro power station in Waikato, New Zealand. It is operated by Mercury Energy. Based on its capacity (estimated), it can supply roughly 192,219 homes (estimated). It ranks #9 of 43 New Zealand power plants by installed capacity. Commissioned in 1929, it is around 97 years old — an older, legacy facility. As a non-combustion source, it has no direct CO₂ emissions from generation. In context, hydro supplies about 54.8% of New Zealand's electricity; the national grid averages 93 gCO₂/kWh (88.5% low-carbon) (2025).
Plant data: WRI Global Power Plant Database (CC BY 4.0), id WRI1000316.
Installed capacity (MW), WRI Global Power Plant Database (CC BY 4.0).
Operated by Mercury Energy. All plants by this company →
This hydro plant converts the energy of falling or flowing water through hydro turbines. It sits in a temperate oceanic climate (Köppen Cfb) — Southern Hemisphere, latitude 38.1°S — which shapes how much energy it can produce and how its output varies through the year.
Monthly mean temperature
Heating degree-days here run 25% below 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: 40/100 — this site sits in the mid 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 #7 largest hydro power plant of 24 in New Zealand by capacity.
New Zealand has 24 hydro power plants in this dataset, together about 4,388 MW of capacity.
Coordinates -38.0714, 175.6433 from WRI Global Power Plant Database (CC BY 4.0). View on OpenStreetMap.
