Hydro power plant in Waikato, New Zealand. Approximate location -38.6158, 176.1425.
HydroWaikatoNew Zealandrun-of-river
Aratiatia is a 78 MW hydro power plant in Waikato, New Zealand. It is operated by Mercury Energy. Based on its capacity (estimated), it can supply roughly 78k homes (estimated). It ranks #31 of 50 New Zealand power plants by installed capacity. Commissioned in 1964, it is around 62 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 WRI1000323.
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 L100000602818); fuel: WRI source-record fuel
At 78 MW, Aratiatia is below the median hydro plant in New Zealand (90 MW). Technically it is described as run-of-river. 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 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 38.6°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 16% 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: 59/100 — this site sits in the mid 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 #15 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 -38.6158, 176.1425 from WRI Global Power Plant Database (CC BY 4.0). View on OpenStreetMap.
Aratiatia is a 78 MW source-record hydro power plant in Waikato, New Zealand, commissioned in 1964.
Its output is enough to supply roughly 78,089 homes (estimated).
Aratiatia is operated by Mercury Energy.
