Genesis increases natural gas prices by 4.5 per cent

Genesis Energy says it must pass on higher costs. Photo / Derek Flynn

Genesis Energy is pushing up gas prices for North Island customers by around 4.5 per cent, blaming increased wholesale prices from a field it has a stake in.

The company says this will mean a $3 to $5 a month increase for customers, dependent on how much natural gas they use, and their energy mix.

Genesis is the country's biggest energy retailer and will announce its annual profit on Wednesday. It says this is the first increase in gas prices since 2013.

''This current increase only impacts North Island customers who are on a Flexi Plan, customers on a fixed-term contract won't see any change until their existing contract expires,'' said a spokeswoman.

Natural gas isn't available in the South Island.

The change will affect 54,000 natural gas customers, LPG pricing isn't part of this review.

Genesis owns a 46 per cent share of the Kupe Oil and Gas Field and takes all of the natural gas from the field. Genesis also has a range of gas supply agreements with most of New Zealand's gas producing or supplying companies.

The retail price changes take effect from October, 1 2018. Customers will see the rise reflected in bills following this date.

Last year the company reported a net profit of $119 million.

It sells natural gas in the North Island and bottled LPG throughout the country. It supplies energy through two retail brands – Genesis and Energy Online – to about 480,000 customers across New Zealand.

Genesis has power stations throughout the country including at Huntly and hydro plants at Tekapo.

Kupe field was first discovered in 1986 and came on stream in 2009. The field is operated by Australia's Origin Energy with 50 per cent and besides Genesis NZOG has a 46 per cent stake.

In April the Government banned new exploration offshore for oil and gas. By some estimates the country has as few as seven years' supply from known sources.