Mercury generates most of its energy from nine hydro stations on the Waikato River and five geothermal plants in the central north island as well as a number of wind farms.

[4] Mercury also service industrial and wholesale market customers offering electricity and natural gas products.

Four years later, law changes obligated AEPB to sell the electricity retailing and generation part of the business.

In 2004, Mighty River Power announced plans to refurbish the Marsden B plant to fire it on coal to increase supply security north of Auckland.

In 2009, Mighty River Power sold the Marsden B plant for $20 million to an Indian company, United Telecom.

Mighty River Power was to be the first company to be partially sold in September 2012, pursuant to legislative changes and market conditions.

[7] However, threatened legal action and unfavourable market conditions saw the Government delay any sale until March 2013 at the earliest.

[8] On 5 March 2012, the Government began taking registrations of interest from the public in Mighty River Power shares.

The Government was slightly disappointed, blaming the Labour-Green policy for putting off many more potential shareholders, with the Finance Minister indicating before the policy was announced that the price would be in the $2.70 to $2.80 range[12] The government retained 51.78 percent of the shareholding, with another 1.02 percent owned by other Crown interests (mainly the New Zealand Superannuation Fund).

On 29 July 2016, after merging its retail and generation businesses the company changed its name to Mercury NZ Limited.

[18] At the same time, the first power from the newly built wind farm at Turitea was generated[19] – adding to the existing portfolio of nine hydro stations[20] on the Waikato River and five geothermal plants[21] located in the central North Island.