Renewable forms of energy are not enough to power Scotland alone, according to the Scottish secretary.
Mr Darling said the renewables industry should increase its share
Alistair Darling told the Scottish Renewables annual conference it was vital to keep an open mind about energy sources, including nuclear power.
Mr Darling attended the green energy trade body's Glasgow event on Monday.
The group warned the government that weakening its support for renewables would have dire results for the green energy sector and climate change goals.
There has been debate about whether or not there should be another generation of nuclear reactors in Scotland.
Scottish Executive ministers have already set a target of having 40% of Scotland's energy supplies from renewable sources, such as wind and wave power, by 2020.
However, Mr Darling told delegates that the UK should not rule out future contributions from any part of the industry, including nuclear.
He said: "Over the years we have maintained secure and reliable energy supplies derived from a balanced and diverse energy mix from nuclear, from coal and from gas.
"There has been a substantial leap forward in renewables and there will be more, but it isn't enough on its own.
"Underlying the energy review is a belief that we cannot afford to be anything but open minded now."
Mr Darling was also visiting Argent Energy in Motherwell, the UK's first biodiesel plant.
The visit came as plans were being made to introduce the Renewable Transport Fuels Obligation from 1 April, 2008.
The obligation requires that all suppliers of transport fuels in the UK ensure that 5% of fuel comes from renewable sources by 2010 in order to meet climate change directives.
At the conference, Mr Darling urged the renewables industry to use the government's energy review to increase its share.
The findings of the Department of Trade and Industry's review of energy needs will be published later in the year.
Scottish Renewables' response to the review included a report on Scotland's renewable future.
It stated that if the executive and UK Government maintained strong support for renewables, by 2010 Scotland's renewable energy sector could deliver up to 30% of the country's electricity needs and up to half by 2020.
Maf Smith, the trade body's chief executive, said: "So much more needs to be done.
"Energy used to heat our buildings accounts for more than half of all energy use and transport nearly 30%, but little is being done to tackle these.
"We call on the government to get to grips with these now."
Scottish National Party energy spokesman Richard Lochhead claimed Labour were already set on a nuclear future.
He said: "By turning their back on our renewable options Labour is denying Scotland the green future which would protect the environment, create jobs and secure our energy future."
Shiona Baird, the Green Party energy spokeswoman, also doubted the UK Government's "open mind".
"The nuclear option puts our future energy supply on incredibly shaky ground," she said.