At a Glance
15 GWh (EST)
Esk Hydroelectric Power Scheme demonstrates how we are expanding our generation assets in innovative and environmentally-sensitive ways. This new Scheme sits in steep hill country, at 450-880 metres (m) in altitude. From here, Rimu and Toronui Power Stations take advantage of a relatively high head, or height from intake to generation, to produce electricity from a small volume of water.
Rimu Power Station has a head of 340 m and uses a maximum flow of one cubic metre a second (m3/s) of water to produce up to 2.4 MW of power. Toronui Power Station has a head of 140 m and uses no more than 1.2 m3/s to produce up to 1.4 MW.
Production efficiency is maximised by state-of-the-art equipment, notably vertical Pelton turbines with high-efficiency generators.
Resource Consents and land access agreements are in place for all of the Scheme components and transmission.
Environment and recreation
Toronui Power Station has a headpond to store water for peak-power-use hours, but it’s only about 4,000 cubic metres. Both Rimu and Toronui are referred to as ‘run-of-river’ Schemes.
Any water taken for generation is above the consented minimum river flow, so the natural river environment is maintained. At Rimu Station, the water used for generation is returned to the natural river within 2 kilometres. At Toronui Station the water is returned within 700 m.
As a result, hydroelectric generation at Esk has a minimal impact on the environment, while providing a significant boost to New Zealand’s energy availability.