Marcel McKeigue, Carl Thornton and Graham Hawrysh, the directors of liquidated firm Cleartrade, have been disqualified for 15 years each - the maximum period handed out by the High Court.
The ban means the directors cannot promote, manage, or be a director of a limited company until 2031.
An Insolvency Service investigation found that between November 2011 and October 2012, Cleartrade sold voluntary emission reductions (VERs) to members of the public which had no potential to show a return.
The carbon credits were sold at highly inflated prices and conned investors out of a total of £1m.
The disqualifications come after an investigation by the Public Interest Unit, a specialist team of the Insolvency Service, which decided to wind up the company.
Anthony Hannon, official receiver in the Public Interest Unit, said: “This company’s claims about the profits to be made by buying its carbon credits were quite simply untrue and only the company and those working for it made money.
“The lengthy periods of disqualification handed down in this case show that this kind of behaviour will not be tolerated by the Insolvency Service nor by the Court.”
The trio are the latest fraudsters in the UK caught running dubious investments in renewable energy scams.
Last December, three former directors of Worldwide Commodity Partners Limited (Worldwide), another scheme selling worthless VERs, were banned by a UK court for a total of 44 years after investors in the fraudulent investment lost almost £3m.