The Highbank Power Station is a small run of the river hydroelectric generator in Mid Canterbury. Owned and operated by Manawa Energy, the station generates power from the Rangitata Diversion Race (RDR) irrigation scheme when agricultural water demand is low. The water is discharged into the Rakaia River when in operation as a generating site, following upgrades made, the site is also capable of pumping water out of the Rakaia River back up the penstock to increase the water availability for agricultural irrigation during the peak summer months.

On 16 June 1945 (1945-06-16) the Minister of Works, Bob Semple, opened the power station, and "set the 36,000bhp in motion".

The Highbank Power Station was constructed as part of the Rangitata Diversion Race (RDR) irrigation scheme by the Public Works Department.

The primary purpose of the RDR scheme was for the irrigation of farmland, not the generation of Electricity. This irrigation diversion race is the source of the water for the Highbank Power Station. When agricultural demand for water is low the water is used by the station to generate electricity, this is typically during the winter months.

Work began in the early 1940s, starting with the construction of an access road.

The outbreak of World War II saw the project delayed due to manufacturing, material, and manpower shortages. The projects completion in June 1945 had followed the completion of the RDR in September 1944.

An unfortunate event was the sinking by enemy action of the ship which was carrying to New Zealand the stator for the generator at Highbank. This necessitated the manufacture of a new stator in England.

There was considerable damage by flooding in the area of the Highbank irrigation and power scheme due to floods in February 1945, this necessitated the village of Highbank being relocated 390 m (0.24 mi) upstream of the powerhouse and a new approach road made.

Construction began in 1939 with the power house structure finished in 1942, The Modern Reinforced concrete structure is some 37 m (120 ft) long and 16 m (52 ft) wide. The height of approximately 16 m (52 ft) allowed for the installation of both the 90 Ton crane, and 10 Ton aux hoist.

Both the Generator and Turbine were manufactured by English Electric co and installed from 1942 till the commissioning in 1945. The Generator installed was the largest in New Zealand at the time of its installation.

The single large vertical shaft generator is driven by a 36,000 bhp (27 MW) francis turbine at 300 rpm. The English Electric Generator is rated for 26.5MW of output with a synchronous speed of 300rpm, making it a 20 pole unit so as to match the 50hz of the National Grid

The Highbank Power Station is connected to EA Networks 66kV network. The 66kV line is a spur line beyond Methven, connecting back to the Methven Substation "Methven66" (MTV). The power is generated at 11kV and stepped up to 66kV for transmission on site.

In the 1970s the station generation capacity had reduced to approximately 65% of the original rated capacity due to sediment build-up and wear on mechanical components. This led to the turbine runner being replaced along with improvements in sediment control at the canal intake and ongoing removal of sediments to reinstate the original performance

TrustPower (now Manawa Energy) installed and operates river intake, fish screening, and pumping facilities to deliver the water from the Rakaia River to the RDR using some of the existing Highbank Power Station facilities. The Highbank Power Station has been equipped with an array of six 1.5 MW pumps that allow it to take water from the Rakaia River and pump it up the power station penstock 104 m (342 ft) into the RDR. The water is then available for irrigators to use.

TrustPower(now Manawa Energy) generation manager Mike Kedian believed pumping water back through the penstock was a New Zealand first.

Pumping water up hill is not without its challenges, and one of these is the volume and pressure of the water contained in the pipeline when being pumped. In order to protect the penstock from pressure fluctuations an air-chamber has been installed adjacent to the pump station to maintain pipeline pressure within acceptable bounds.

Manawa Energy plans to Replace the existing assets with 1 new 29MW turbine and a new generator. Replacement of both generator and turbine provide for a more efficient generation of electricity using the available water. (+8GWh pa). The project is estimated by Manawa Energy to take 18 months and cost NZ$30.5m, Replacement commenced October 2024. The nearly 80 year old equipment had reached end of life, along with the generator and turbine other mechanical and electrical equipment on the site will be replaced.

The Highbank generator being synchronized before being reconnected to the rest of the network is vital, The generator can suffer irreparable damage if it is not in sync. Manawa Energy shuts down the Highbank generator to guard against out of synchronism events before reconnecting, this protects the generator, but leads to inefficiencies and delays in bringing its capacity back online.

This project has been postponed until 2025.

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