Spectrum for 15 May 2011

Wind strength and constancy make The Tararua Wind Farm, on the ranges behind Palmerston North, one of the world's most efficient electricity producing sites. One turbine, with 90 metre diameter blades, made by the Danish firm Vestas, generates enough electricity in two and a half hours to keep a home supplied for a year. Spectrum's Jack Perkins explores the site and climbs inside one of the 60 metre high towers.