In the face of escalating power costs rural Maori settlements are turning to generation of their own power from local resources.
NGATI KEAROA NGATI TUARA, one of three Te Arawa sub tribes in Te Arawa River Iwi Trust, has completed a micro-hydro project at its marae at Kearoa, south west of Rotorua (becoming the first marae to generate its own power).
The idea emerged at a renewable energy hui at Kearoa Marae in 2011 and a feasibility study identified the nearby Pokaitu Stream as suitable for a micro-hydro unit. At the turn of last century, the stream site had been used to power a waterwheel for a flax mill.
A 600mm pipe conveys the water to the headstock where the turbines are located. The headstock is designed to hold six turbines, but only three have been installed so far. A flow rate of approximately 50 litres per second is required for each turbine, so the maximum requirement for the system is 300 litres per second. This is less than half of the summer low flow (700 litres per second).
The water drives the propeller turbines as it falls around three metres back to the river via draft tubes. The water returning to the river falls on solid rock, which prevents erosion.
It was estimated that each turbine should generate 700 to 800 kilowatts. The three turbines produce 2.5 kilowatts per hour, powering the marae and a nearby iwi-owned trust farm that grows vegetables in hydroponic glasshouses. Excess power is sold into the grid.
Project manager Eugene Berryman-Kemp says the unit has been so effective it has saved over $4000 in power costs over the past year.