State-owned power company Genesis Energy has more than doubled its half year profit to $38.3 million for the six months to December.
The 125% increase on the same time a year earlier is due to higher gas and electricity sales and the company's one-third share of petroleum sales from the Kupe Oil and Gas Field.
The acquisition of Tekapo hydro stations and a 30% rise in the wholesale price boosted electricity revenue.
Chief executive Albert Brantley says earnings grew 37% to more than $190 million.
He says the industry is concerned about low hydro storage levels in the South Island but his company can draw on other assets to generate power.