The four 50 MW units were decommissioned and removed in 2001, and used in the construction of the Valley Power Peaking Facility in Australia.

In February 1995, the board of inquiry concluded that the station's operation would significantly increase New Zealand's emissions of carbon dioxide and make it more difficult for the Government to meet its obligation to reduce the emission of greenhouse gases to their 1990 levels as committed to under the United Nations Framework Convention on Climate Change.

[3] In March 1995, Upton approved the expansion of the station to 400-megawatts on the condition that forests were planted to create a carbon sink or the effect of emissions was reduced by greater efficiency elsewhere.

[4] In June 2003, a hearing committee of the Taranaki Regional Council granted an application to delete the consent conditions requiring mitigation of carbon dioxide emissions.

It comprises two LMS100 gas turbine units in open cycle configuration,[7] and is used as a peaking power plant, to complement hydro and wind generation.