Greenhouse gas emissions during this year's dry autumn rose 25% on the same period last year, as the country resorted to fossil fuels to avert a possible electricity shortage.
A big drop in hydro generation, because of low lake levels, corresponded with a leap in the amount of electricity generation from fossil fuels.
Electricity output from coal and gas fired power stations rose 15% on a year earlier.
There was lower output from windfarms, due to a large number of still days.
The figures come from the Ministry of Economic Development and cover the June quarter.
Generator to be looked at
A decision five years ago, to create a back-up electricity generator to ward off a power crisis, is to be scrutinised.
A diesel-powered generator was set up at Whirinaki, north of Napier, after the 2003 electricity crisis - which was the second in two years.
Critics believe the use of diesel makes the power from Whirinaki too expensive.
They also say its location is at the wrong end of an already inadequate transmission line from Auckland, the region with the biggest demand.
An inquiry into this year's electricity concerns, led by the former Contact Energy chief executive, David Hunt, will look at both of these issues before wrapping up in November.