A native Maori tribe and its co-owners in a geothermal generating field, have opened the plant to the public.NGAWHA, Northland, NZ, 2002-01-11 [SolarAccess.com] The facility is near the Ngawha Hot Springs health spa, which has provided mineral hot waters for more than a century. The Top Energy utility generates one third of the power in northern New Zealand using renewable energy. The utility is in a joint venture with the local tribe’s Tai Tokerau Maori Trust Board which owned the land. Two 6 MW Ormat organic binary cycle turbines from Israel were installed at a cost of US$12 million, to use hot brine extracted from two production wells and a 1 km steam line to heat the secondary working fluid, pentane. The cooled brine and condensate are pumped along a 3 km re-injection line and disposed of in two re-injection wells. The geothermal station was built in 12 months, and uses a closed system design where corrosive or toxic geothermal fluids are kept separate from mechanical parts of the plant and the surrounding environment, and then are re-injected into the geothermal field after use. Top Energy’s electricity grid spans an area of 6,822 square kilometres, using 4,500 km of power lines to serve an average of 5 customers per kilometre.