Climate campaigners have called for a halt to plans to build an incinerator to burn all of north London’s waste, after the cost figures quoted by the waste authority skyrocketed – almost doubling from £650m to £1.2bn.

The major piece of public infrastructure in Edmonton was given the go-ahead by the government two years ago, and would burn all of the rubbish from Hackney, Islington, Barnet, Camden, Enfield, Haringey and Waltham Forest to generate electricity.

The existing plant - which dates back to 1969 - is coming to the end of its operational life, and the North London Waste Authority (NLWA) says it needs to be replaced to avoid putting rubbish into landfill - which it claims would produce more carbon dioxide than incineration.

In July the NLWA told the Gazette the estimated cost of the whole of the North London Heat and Power project, which includes the incinerator or "energy recovery facility", was £650m. The project includes a community centre to promote the circular economy and a resource recovery facility to separate recycled waste.

Four months on the cost of the project is now quoted at £1.2bn.

The NLWA claims it is "inaccurate" to say the cost has doubled, claiming: "NLWA has always been clear that the details of the final cost would be determined between 2017 and 2020."

The figure offered now includes £250m for "comprehensive works to prepare the site and delivering the project in the next decade" and a "risk allowance" of £250m which it says is "proportionate for a project of this scale".

"If we're serious about tackling the climate emergency, any delay to this vital project would be completely irresponsible," said a spokesperson.

But Carina Millstone, who co-founded the campaign group Stop the Edmonton Incinerator Now, said it was an "absurd notion that we can somehow burn our way out of climate change, as incinerators emit large quantities of carbon dioxide".

Although in a February 2018 statement by the waste authority preparatory works were referenced, no additional cost was mentioned and Ms Millstone questioned why the new figure has only now been published.

"The total cost figure of £1.2bn is new, and indeed it basically sounds like it's doubled. This is a lot of public money," she said.

She called on the NLWA - the UK's second largest waste disposal authority, which deals with three per cent of the UK's waste - to pause the project - which has been 10 years in the making - to reflect on changes in legislation and policy recommendations following the declaration of a climate emergency.

"In an emergency, business-as-usual no longer work and decisions must be reviewed," said Ms Millstone.

"We are asking that before they commit £1.2bn for a piece of infrastructure that will be there for the next 50 years, why don't we just review the project now."

In June the European Union's sustainable finance taxonomy report recommended that incineration should be viewed as contrary to the circular economy. The UK government's resources and waste strategy recommends promoting a circular economy, which aims to eliminate waste and the continual use of resources.

The EU report states the "waste to energy" incineration model is no longer sustainable and that it harms the circular economy by producing toxic waste, air pollution and contributing to climate change, as well as removing the possibility of ever recycling what is burnt.

Ms Millstone said: "There is undoubtedly a change within policy makers and the consensus that landfill is better than incineration no longer holds, both for climate and for the circular economy.

"Burning waste releases greenhouse gases immediately, whereas well managed landfill, with organic waste separated, out doesn't. And crucially, the material is lost forever if burnt, whereas if well managed in landfill, it could be mined and recycled when technologies become available."

A spokesperson for the NLWA said the taxonomy report has not yet been adopted in EU policy and said it preferred to stick with the EU's circular economy action plan, which has been adopted. This states that "when waste cannot be prevented or recycled, recovering its energy content is in most cases preferable to landfilling it, in both environmental and economic terms".

They cited a Wikipedia page which puts landfill at the bottom of the "waste hierarchy" based on a 2002 study.