New Zealand's use of fossil-fuel produced electricity jumped by 40 per cent in the second quarter as drought conditions in the South Island put pressure on hydro generation.
That's according to a report published by the Ministry of Business, Innovation and Employment, which showed thermal power generation- electricity made from burning gas, coal, oil and recycling waste heat - rose to 3918 gigawatt hours in the three months to June 30, compared with 2820GWh in the first three months of the year.
Meanwhile electricity generated from hydro lakes fell 6.3 per cent to 4872GWh, which the report said was due to "record low hydro inflows in the South Island for much of the first half of the year".
That saw the renewable share of electricity generation drop to 64 per cent from 72 per cent in the first quarter and 79 per cent a year ago.
The ministry said the decline in hydro generation could have resulted in a sharper drop off of in the renewable ratio had it not been for additional wind and geothermal production which has come online in recent years.
The official figures show wind and geothermal sourced power rose modestly by 1.4 per cent and 0.8 per cent respectively to 498GWh and 1469GWh.
Still, the spike in thermal electricity saw greenhouse gas emissions double on a yearly basis to 2412 kilo tonnes of carbon dioxide equivalent emissions.
Energy sector emissions account for about half of the greenhouse gas produced in New Zealand, with the remainder coming from agriculture.
The report said energy sector emissions are almost 5 per cent above 1990 level on a per capita basis, but were down from levels seen in the year 2000.