Scotland is likely to lose all of its electricity-generating capacity from large plants within 25 years, an independent inquiry has found.
The inquiry is calling for supply to be diversified
The research, Inquiry into Energy Issues for Scotland, was carried out by the Royal Society of Edinburgh (RSE).
It said urgent steps must be taken to achieve a secure, competitive and low carbon emissions energy supply.
Renewable technologies should be developed, but new nuclear plants should not be ruled out altogether.
The inquiry by the RSE, which is an independent and non-party political educational charity, was set up to review energy supply and demand in Scotland until 2050.
The report predicts that between 2000 and 2050 demand for power will increase by 50%.
But at the same time the production of North Sea gas and oil is dropping and coal and nuclear plants are approaching the end of their economic lives.
The report made 37 recommendations "critical to the security of supply".
These should include a variety of sources, such as renewable power and new-build clean coal, gas and nuclear stations.
Among those were improving performance on waste management and improving energy loss in buildings.
No 'magic bullet'
Sir Michael Atiyah, president of the RSE, said urgent action was needed to avoid an energy gap.
He said: "We have to do something, it's vital that we do and decisions have to be taken very soon because of the long timescales involved.
"Diversity of supply will be key as there is no 'magic bullet'.
"We must all work together to achieve a balance of security of supply, continued economic growth, low carbon emissions and affordable fuel for all."
He appealed to the leaders of all the main political parties to engage in an open debate with people in Scotland and across present party-political divides to seek a consensus solution.
Friends of the Earth Scotland criticised the RSE report.
Chief executive Duncan McLaren said: "Despite making some strong recommendations on energy efficiency and the need for a Scottish energy policy, this report offers merely a conventional centralised vision of electricity generation which would fail Scotland and the Scottish economy.
"By seeking to leave new nuclear build as an option - despite public opposition - investment in renewable energy and energy efficiency will be undermined."
Environmentalists want more focus on green energy methods
Maf Smith, chief executive of Scottish Renewables, said the report contained interesting recommendations but said it was a "bit of a curate¿s egg".
He added: "Unfortunately many of its recommendations fail to see what is already happening in Scotland: our energy future has a strong renewable heart, and we need to see investment in a range of renewable technologies, so that we can ensure security of supply from clean energy sources."
Responding to the report, a Scottish Executive spokesman said: "It is clearly important for us to have a mature and well-informed debate around the choices and opportunities related to the creation of a secure, affordable, low carbon energy future for Scotland.
"The work of the UK Energy Review is ongoing and we expect its conclusions later this summer.
"We will therefore consider the RSE's report in greater detail in due course, in the context of the UK Energy Review, and alongside other contributions to the energy debate."
The SNP's energy and environment spokesman Richard Lochhead said the report "got it wrong" on the nuclear issue.
He added: "The bottom line is that with Scotland's enormous renewables potential, there is no need for nuclear in 21st-century Scotland."
Alex Johnstone, Scottish Conservative's energy spokesman, called for a "more balanced approach in supporting other renewable technologies", while the Liberal Democrats described the report as "oddly backward looking".