Mighty River Power's new geothermal power station near Taupo has reached full capacity for the first time.
It is the third major geothermal plant for Mighty River and took over two years to build.
Development general manager Mark Trigg said reaching full capacity is a milestone.
Testing at the station will continue for the next two months, but once it is fully operational it will increase Mighty River's geothermal electricity production to 40% of total generation. The station will run constantly.