The financial position of the Tiwai Point aluminium smelter has improved to its best level in years, but it has renewed its criticism of the high cost of power.
The smelter's owner, Pacific Aluminium, made an after-tax loss of $18 million for the year ending in December, compared with a net profit of $67m the year before, because of an accounting write down in the value of contracts it used to insure against power price volatility.
However, the underlying profit was $75m, up from $25m in 2016, as it benefited from a 23 percent rise in world aluminium prices.
Tiwai Point chief executive Gretta Stephens said it continued to be hit by unreasonable power transmission costs - $72m last year - and would rise again this year.
"We believe businesses should pay a fair price for the transmission services they receive. This is not what is happening under the current system."
She said the overall result had given greater confidence about the smelter's long-term future.
"But predictions are for aluminium market conditions in 2018 to be volatile and [the smelter] remains vulnerable to that market volatility as well as movements in the New Zealand dollar against the US dollar," Ms Stephens said.
