UPDATED 3.41PM Our last remaining coal power plants are sticking around for longer than expected, but the Government says it's still focusing on cleaner energy.

The two units at the Huntly Power Station were due to close in 2018, but that's now been extended by four years, to 2022.

Energy Minister Simon Bridges said it was necessary to extend it, as Genesis needed more time to make the transition.

"Even though it's been kept on, if you like, to give us a back-up, it's only going to run if there's real problems which security of supply, that is if there's a real fear the lights are going to go out."

Mr Bridges said he is confident 2022 is the final closure date, with no further extensions.

"Genesis made it quite clear in terms of its business it doesn't see any need for this plant."

Grid owner Transpower is relieved at the news, saying it would be hard to meet the country's demand for power if Huntly was turned off in 2018 as originally proposed.

But Greenpeace climate campaigner Jeff Harrison said power companies should be turning to cleaner, cheaper sources like wind farms, but instead are sticking to the status quo - with coat the dirtiest fuel on the planet.

Mr Harrison said coal generates less than four percent of our power yet accounts for 28 percent of our electricity pollution, with the Huntly Power Station being the biggest single source of New Zealand’s carbon emissions.

Green Party energy spokesman Gareth Hughes said the extension shouldn't be necessary.

"They've had eight years to prepare for more renewable electricity, but in fact their policies have seen more coal being burnt in New Zealand at a time when the rest of the world's walking away from the most polluting types of fuel."