I agree completely with James.
Even if one company was complete green (red?), those forms of generation are so inconsistent that anytime there is a shortfall from the wind turbines it has to be made up by something like the diesel generator in Hawkes Bay. Besides about 65% of NZ's power is renewables anyway, mainly from the hydro in the SI and geothermal from the central NI. Ironically the power companies don't seem to be able to get resource consent to develop new generation based on these energy sources because it either upset the local iwi or ruins the fishing. The Meridian CEO recently admitted that wind turbines only run at full efficiency 25-30% of the time. How can a country base its energy policy on something so unpredictable?
Meanwhile we are exporting millions of tons of lignite to China and India every year from Southland. The whole system is completely insane, but that's what happens when political ideologues take over the asylum.