Unions at troubled Kellingley Colliery have written to government ministers urging them to secure a long-term future for the pit.
UK Coal - backed by £20m of investment from the government and private sector - plans to close Kellingley, with the loss of 700 jobs, by December 2015.
But a report published on behalf of the Trades Union Congress (TUC) and the National Union of Mineworkers (NUM) claims the deal would cost the government a total of £75 through loss of income tax and costs in unemployment benefits.
Instead, the unions urged the government to apply for European Union state aid, which they claim would keep Kellingley - and under-threat Thoresby Colliery in Nottinghamshire – open until at least 2018.
Chris Kitchen, NUM general secretary, said: “I’m hoping the government will listen to us that’s why we’ve spent so much money on the report.
“It’s a Conservative-led coalition government, with a Conservative energy minister, and there’s obviously a lot of history between miners and the Conservatives.
“But this report has been done by an independent consultant and it proves it would be more beneficial to fund a longer-term future.”
Andrew Mackintosh, UK Coal’s director of communications, said the firm was still working on preventing an immediate closure of Kellingley.