Te Rapa cogeneration

{{Use dmy dates|date=July 2019}}

{{Use New Zealand English|date=July 2019}}

{{Infobox power station

| name = Te Rapa cogeneration

| image =

| image_caption =

| location = Te Rapa, Hamilton

| country = New Zealand

| coordinates = {{coord|37|42|59|S|175|13|0|E|region:NZ_type:landmark|display=inline,title}}

| owner = Contact Energy

| status = O

| th_fuel_primary = Natural gas

| ps_cooling_source = River water cooling tower

| ps_cogeneration = Yes

| ps_combined_cycle =

| ps_units_operational = GE frame 6B

| ps_electrical_capacity = 44 MW

| commissioned = 1999

| decommissioned = July 2023 (planned)

}}

The Te Rapa cogeneration plant is a 44 MW cogeneration plant owned and operated by Contact Energy. It is located at the Fonterra dairy factory, at Te Rapa near Hamilton in New Zealand, and was commissioned in 1999.{{Cite web |date=23 February 1999 |title=Contact Energy Limited |url=https://www.beehive.govt.nz/release/contact-energy-limited |access-date=2023-03-14 |website=The Beehive |language=en}}

The construction of the plant came as part of a wider upgrade to the dairy factory proposed in 1997. The original capacity applied for under the Resource Management Act was 150 MW, but there was opposition from Greenpeace about the carbon dioxide emissions and Tainui about pollution of the Waikato River; Subsequently the planned capacity was reduced to 45 MW and the change was announced at an Environment Court prehearing. The Waikato Times reported that “Greenpeace was pleased [with the change] but said even the smaller plant would pump out 100,000 tonnes of carbon dioxide”.{{cite news |id={{ProQuest|313469427}} |last1=Fox |first1=Andrea |title=Opponents welcome plan to cut Te Rapa power plant size |newspaper=Waikato Times |date=19 December 1997 }}

The plant is based on a gas turbine (a GE frame 6B) that can produce up to 44 MW of electricity. Hot exhaust gases from the turbine are ducted to a heat recovery steam generator (HRSG) to raise steam. The HRSG has duct burners to increase steam output, which can be up to 180 tons of steam per hour.{{Cite report |url=https://www.mbie.govt.nz/assets/2020-thermal-generation-stack-update-report.pdf |title=2020 THERMAL GENERATION STACK UPDATE REPORT |date=29 October 2020 |pages=33–34}}

The cogeneration plant is designed for flexible operation, and can provide electricity to the dairy factory, export electricity to the local network or import electricity for use in the dairy factory. A common operating mode is 30 MW of electricity exported and 15 MW plus 120 tons per hour of steam provided to the dairy factory.

A 127 MW gas/diesel fired auxiliary boiler is used when the cogeneration plant is not in operation.{{Cite web |last=Stagg |first=David |date=20 November 2019 |title=Waikato Regional Council - S42A Report Fonterra Re Rapa Air Discharge |url=https://www.waikatoregion.govt.nz/assets/compiled-s42A-report-Fonterra-Te-Rapa.pdf |access-date=2023-03-14 |website=www.waikatoregion.govt.nz |page=6 |format=PDF}}

Fonterra has been authorised by the Waikato Regional Council to install and commission an alternative combustion plant if the co-generation plant ceases to be available.