A record after-tax profit of almost $159.6 million, for the year to June 30, was declared by one of the country's biggest power companies Mighty River Power, up $49 million on the corresponding previous period. The company is a power generator and retailer, with more than 350,000 customers via its retail arm, Mercury Energy.

Another 30,000 customers, an increase in renewable energy, and favorable weather in the year under review, were seen as the key drivers behind the notable profit, by Chairwoman Carole Durbin.

She explained that the company's renewable generation capacity was enhanced due to the commissioning of the 100MW Kawerau Geothermal Power Station, which came into production earlier than expected, at a greater capacity and under budget.

"The Waikato Hydro System had higher than average generation of 700GWh more than last year, driven by - in the first quarter of the financial year - the highest-ever inflows in a 90-day period," she said.

Furthermore, prominent higher wholesale prices were received by these higher volumes in the first quarter, due to low South Island storage levels at that time.

The fuel costs were enormously reduced by a 60 percent, in production at Southdown.