The Minister for Communications, Climate Action and the Environment has said it is disappointing that permission to redevelop the West Offaly Power Station in Shannonbridge has been refused.
Richard Bruton said the ESB will need to evaluate why this decision was taken and assess the implications.
Speaking on RTÉ's News At One, Mr Bruton said it is still a priority of the Government to support Bord na Móna's plan to have an "orderly exit" from peat, and to provide alternative employment.
"The ESB will have to look at this and see what the implications for the future are. I think it's premature to be drawing any conclusions.
"From the Government's point of view, we want to ensure that the strategy that Bord na Móna want to pursue - which is to have an orderly exit from peat and to create alternative employment - that remains the priority for Government."
The ESB met workers this afternoon to outline the implications of the decision by An Bord Pleanála.
Willie Noone of the Bord na Móna Group of Unions said there were real fears now for the future of 800 peat workers on the midlands bogs.
He called on Minister Bruton, to intervene and said workers who had been promised a just transition from peat harvesting were now being "dropped off the edge" into redundancy.
ESB Lough Ree Power had sought planning for the continued operation for the peat-fuelled power station to facilitate the failed transition to firing it with biomass.
The planning application had been opposed by An Taisce and other environmental groups.
They claimed the continued burning of peat even for a limited period could not be justified and questioned the viability of the sourcing of biomass by Bord na Móna.
An Bord Pleanála stated the reasons and considerations for its ruling were: "It is considered that the provision of a regionally significant power generating facility, dependent upon the burning of a fuel imported into the facility, needs to be associated with and aligned with strategic energy management, planning and renewable energy policies and plans in order to achieve balanced, orderly development.
"Furthermore, it is considered that the development of such energy infrastructure pursuing optimum sustainable utilisation of renewable energy emanating from the power production process is required in order that such development positively contributes to the environment and that the siting of such development, with accessibility to the supply network of the intended fuel sources, is appropriately located.
"Finally, it is considered that the cessation of the use of peat as a fuel is essential in addressing the generation of excessive greenhouse emissions from the established facility to assist in meeting the State's climate change obligations in the energy sector."
Fianna Fáil's Spokesperson on Public Expenditure and Reform Barry Cowen said the decision must be appealed.
The Offaly TD said the decision is another blow to Bord na Mona and ESB workers in the Midlands who have seen their livelihoods decimated bit by bit.
He accused the Government of being "lethargic" in dealing with the issue, adding that the "speed at which plants are closing and jobs are being lost is completely disproportionate to any investment in the region and the Midlands will be left behind".
Former environment minister Denis Naughten said the refusal is a "devastating blow to the whole region" and called on the Taoiseach to hold an emergency meeting to come forward with proposals aimed at securing local jobs in the short-term "while the current road map for the transition away from peat is re-evaluated".
A spokesperson for the Department of Communications, Climate Action and Environment said: "The Department of Communications, Climate Action and Environment notes the decision of An Bord Pleanála not to renew planning permission for the West Offaly Power station.
ESB and Bord na Móna will now study the implications of this decision carefully. The Department will liaise with both companies to consider the impact of this decision and future steps.
The Government's overall objective is to ensure Bord Na Móna implements its Strategic Plan for the phased transition away from peat and the creation of new, long-term, sustainable employment opportunities for the Midlands into the future."