Production of electricity from geothermal power plants is rising fast.
The Ministry of Economic Development's energy quarterly says electricity from this source rose to 11% of total generation in the three months to December.
The opening of a new station at Kawerau was a major contributor, but other geothermal projects are being developed.
Geothermal electricity is expected to ultimately exceed 20% of all electricity.
This form of energy is favoured by the Government because it is cheap, renewable and has only limited greenhouse gas emissions.
The geothermal rush helped boost total renewable figures for the December quarter, in contrast to a dry winter when renewable electricity performed badly and coal and gas plugged the gap.