Dozens of experts have signed an open letter to the PM, saying Snowy 2.0 is turning into a “$10 billion white elephant”.

The letter, addressed to Prime Minister Scott Morrison and Premier of New South Wales Gladys Berejiklian, warns costs on the massive Snowy 2.0 pumped hydro project will blow out to around double original estimates – possibly hitting $10 billion.

The group of 37 Australian energy, engineering, economic and environmental experts behind the letter wrote to the PM and Premier back in March to warn of “overstated and false claims” used to prop up the Snowy 2.0 pumped hydro project.

The group says more revelations have emerged since then.

They take aim at recent projections by the Australian Energy Market Operator (AEMO), saying the figure highlight the “inefficient, unnecessary and damaging” nature of the project.

AEMO’s forecasts show Snowy 2.0 will not pay for itself, and will not actually be not needed until the 2030’s, by which time battery storage, demand response and other technologies will have come into their own.

“It is now even more clear that there are numerous alternatives that are lower cost, more efficient, quicker to construct, and incur less emissions and environmental impacts,” the letter says.

The experts raised concerns about costs too, saying; “the Business Case estimate of $3.8 – $4.5 billion is understated, also by around 100%”.

“It has been disclosed that the estimate does not include all project costs, and has already been exceeded by a $5.1 billion contract for just a portion of the works.

“Once all costs are added, including the associated transmission lines, we predict the total to be in the vicinity of $10 billion.

“Not only has output been overestimated by 100%, Snowy 2.0 is not urgent, nor critical for the transition to renewable energy, nor ‘renewable’,” the letter states.

“Snowy 2.0 should never have been approved and, if constructed, will be a $10 billion White Elephant.”

With $1 billion already spent on the project, the signatories say “it is well time to cut the losses – there is still $9 billion or more to be saved on behalf of Australian taxpayers and electricity consumers.”

“We again urge your Governments to undertake an independent expert review of Snowy 2.0. Recent information confirms that Snowy 2.0 is not critical, not viable, uncompetitive, wasteful, and will devastate vast areas of Kosciuszko National Park. There are far better alternatives.”