So-called greener alternatives to a waste-burning power plant have been rejected as unviable by the seven north London boroughs behind the scheme.

The North London Waste Authority (NLWA) will press ahead with plans for a new incinerator in Edmonton – claiming a delay to the project would undermine efforts to tackle the Climate Emergency.

Environmental group Extinction Rebellion had called for the scheme to be paused so an independent review could be carried out to look at more eco-friendly alternatives.

The campaign group claimed the plant would pump out harmful emissions and – at an overall cost of £1.2 billion – saddle councils with a large debt burden.

But in a letter published on Tuesday (April 21), the NLWA – made up of Enfield, Barnet, Haringey, Waltham Forest, Camden, Hackney and Islington councils – described the alternatives proposed by Extinction Rebellion as “untested and unrealistic”.

NLWA chairman Cllr Clyde Loakes says in the letter: “We cannot rely on the unproven, inefficient, unsustainable and frankly ill-informed solutions proposed by Extinction Rebellion for the tonnages we are ultimately responsible for.

“The North London Heat and Power Project continues to be the only sustainable and responsible solution.”

The new incinerator at Edmonton EcoPark – lying to the north of the North Circular and west of the River Lee – will process up to 700,000 tonnes of waste a year at peak capacity, while generating electricity and heat for up to 127,000 homes.

According to Cllr Loakes, alternatives to the plant were rigorously analysed as part of the planning process – but each of them was found to have “major limitations”.

His letter describes “distributed modular gasification” as “under development and unproven, even on a small scale”.

Cllr Loakes claims mechanical biological treatment “increases the carbon footprint of waste treatment and comes at a higher cost than energy recovery”.

Another alternative, pyrolysis and gasification, is described as “still unproven at the scale required to treat north London’s non-recyclable waste”.

Cllr Loakes pointed out that while the waste authority plans to boost recycling rates significantly, there will still be residual waste that cannot be recycled – and this should not be sent to landfill.

He said the new facility would be equivalent to a 215,000-tonne carbon saving when compared to landfill, which is “like taking 110,000 cars off the road every year”.

And he said the published analysis “shows categorically that no concentrations of pollutants from the facility will breach any air quality or public health standards”.

The new incinerator will be fitted with filters to capture particulate matter and extract pollutants from the emissions it produces.

Cllr Loakes also claimed the project had been “subject to a rigorous and independent planning process, which fully considered environmental factors, alternative options for treating non-recyclable waste and air quality impacts”.

Construction of the new incinerator is due to begin in 2022. It will be accompanied by a “resource recovery facility” designed to extract wood, plastics and metal for recycling.

Extinction Rebellion has been approached for comment.