In contrasting results for two of the country's electricity generators, profits at Genesis Energy have risen Mighty River's tumbled.
Genesis Energy tripled its first-half net profit due to one-off rises in asset values as well as a strong underlying performance.
Net profit for the six months ended December rose to more than $68.2 million from $19.7 million in the same six months the previous year. Genesis owns 31 percent of the Kupe oil and gas field.
Chief executive Albert Brantley said the improved performance came despite challenging electricity and gas retail conditions, mixed weather, lower export crude oil prices and some of its stations being offline at times.
The company lost 3 percent of its electricity customers in the six months, to 517,492.
However Mighty River Power's profit dropped tumbled after it quit its international geothermal plans.
It made a net profit of $8 million in the six months to December, compared with $124 million in the same period a year earlier.
Mighty River booked $83 million in impairment costs from ending its involvement in developing geothermal sites in Chile and Germany.
Gross earnings fell four percent to $259 million due to lower hydro generation and commercial sales.
The company, which is 51 percent owned by the Government, said it remained on track to pay a full year dividend of 14 cents a share.