Wairakei field

Story

The Wairakei Power Station is a geothermal power station near the Wairakei Geothermal Field in New Zealand. Wairakei lies in the Taupo Volcanic Zone.HistoryThe power station was built in 1958, the first of its type in the world, and it is currently owned and operated by Contact Energy. A binary cycle power plant was constructed in 2005 to use lower-temperature steam that had already gone through the main plant. This increased the total capacity of the power station to 181MW. The Wairakei power station is due to be phased out from 2013, replaced by the Te Mihi geothermal power station. The Poihipi Power Station was built in 1996 at a nearby site in the same field.UnitsWairakei A station Unit 1 – 11.2 MW intermediate pressure Unit 4 – 11.2 MW intermediate pressure Unit 7 – 11.2 MW low pressure Unit 8 – 11.2 MW low pressure Unit 9 – 11.2 MW low pressure Unit 10 – 11.2 MW low pressure Units 2, 3, 5 and 6 were decommissioned in 1984.Wairakei B station Unit 11 – 30 MW intermediate/low pressureUnit 12 – 30 MW intermediate/low pressureUnit 13 – 30 MW intermediate/low pressure Wairakei Unit 14 – 4 MW intermediate/low pressureWairakei Binary Plant – 14 MW binaryEffectsThe use of steam from the field has had a number of visible effects on the local environment. Visible geothermal activity has increased (due to changes in the water table / water pressure allowing more steam to be created underground, upsurging at places like Craters of the Moon), while there has also been some land subsidence and reduction in steam volumes from the field after some decades of use. Recent total electrical production has been sustained or increased with the investment in additional power stations such as the binary plant of 2005 designed for lower-temperature generation, but the total still does not reach the early power levels such as the 192MW reported in 1965 (NZED Annual Statistics), for instance. Some power stations in the field are now capped in their extraction capacities and a substantial part of the water / steam is being reinjected after use.