Electricity supply in developed countries is straining to cope with demand, an International Energy Agency (IEA) report suggests.
California's power outages in 2001 may have been a sign of things to come
In a report called 'Saving Electricity In A Hurry', the agency predicts there will be outages like those experienced in the United States, Japan and Canada.
Several developed countries have experienced power shortages and more are likely to occur, it says.
A mix of factors lead to power cuts but pre-planning rarely happens, it adds.
The report lists recent electricity outages in the United States, Japan, New Zealand and Canada and says there is "reason to believe that this list will grow".
"There is every reason to expect that another shortage... will appear soon," the report concludes.
Consumers may see higher electricity prices, but this could reduce the risk of further crises in the long term.
"Saving electricity in a hurry is not an elegant localised operation like building a new power plant; it is a messy chaotic activity with groups scrambling all over (and sometimes bumping into each other)," the report lays out.
"It can be expensive in unfamiliar directions, such as for advertising, rebates, and other subsidies.
"But this may be the only alternative to much more severe economic dislocation and disruption," the IEA warns.
The Californian electricity crisis of 2001 was triggered by a variety of factors including "bungled deregulation" and "outright market manipulation" by energy companies, it says.
Power outages can be attributed to a mix of factors
This was then exacerbated by a drought and "mandatory price caps" that kept electricity cheap.
The end result was a crisis that was estimated to cost the state at least $893m (£490m; 730m euros).
The report looks at how consumers can be encouraged to save energy.
"In a crisis, it is acceptable to request consumers to make themselves more uncomfortable, hotter in the summer, colder in the winter, and be inconvenienced," says the report.
'TV in the dark'
Some of the advice peppered through the report makes almost amusing reading.
During a power shortage in New Zealand, people were asked to watch TV in the dark.
During the electricity crisis of 2001, Californians were asked to "unplug their second (or third) refrigerators".
The IEA also recommends "shorter showers", making traffic lights flash instead of remain on permanently and even reducing the speed of lifts and escalators in commercial buildings.
When power is short, maybe one fridge will do
Tips on how to save energy could be printed on "paper tray liners in fast-food restaurants".
Measures as radical as changing the clocks to fit daylight hours are suggested as possible energy savers.
"Britain exploited the energy-saving aspects of Daylight Saving during World War Two. Clocks were changed two hours ahead of GMT during the summer (which became known as Double Summer Time).
"The clocks also remained one hour ahead of GMT though the winter."
Of course, even Rebecca Loos and Abi Titmuss may be called upon to help out were Britain about to be plunged into darkness.
"A vital element of the campaign is raising conservation to the level of a civic obligation, patriotism and, if possible, fashionable and 'cool'," says the report.
"The information campaigns in Tokyo, California, New Zealand and Brazil enlisted celebrities in their television and print advertisements to help achieve that goal."