New Zealand's biggest electricity generators are embarking on an investment drive that could boost the country's wind generation capacity by more than 70 per cent in coming years and lift geothermal power capacity by as much as 10 per cent.

Govt won't 'die in a ditch' for 100 per cent renewable target

The potential spending, more than $1 billion, is being driven by a desire to reduce emissions and an expectation that in 2022, Contact Energy will close the country's second-largest gas-fired power station — the 23-year-old Taranaki Combined Cycle plant.

Mercury NZ is planning a 119 megawatt