A climate change campaign to get everyone to switch off their lights will not reduce carbon emissions, according to electricity experts.
Published: 8:00AM GMT 27 Mar 2010
Earth Hour, organised by the World Wildlife Fund (WWF), will see millions of people switch off their lights for an hour this weekend.
But the fall in electricity use for such a short period is unlikely to result in less energy being pumped into the grid, and will therefore not reduce emissions.
Even if power stations are turned off, the upsurge in turning the lights back on one hour later will require power stations that can fire up quickly like oil and coal.
Energy experts said it could therefore result in an increase in carbon emissions "rendering all good intentions useless at a flick of a switch".
But WWF said the campaign was about raising awareness and saving energy in the long term, rather than a short-term fix.
Millions of buildings around the world are expected to go dark at 8.30pm on Saturday including the Sydney Opera House and Big Ben.
WWF Earth Hour is designed to raise awareness of climate change and has been supported by Al Gore and the United Nations.
This year more than 50 million people are expected to take part on every continent in the globe in the biggest Earth Hour since the event began three years ago.
Ross Hayman, of the National Grid, said only a small fall in demand is expected in the UK, meaning the event will not cause less energy to be put into the grid.
However, he warned that even if there is a significant drop and supply is turned off, the reduction in energy will be offset by the surge needed to turn bring energy back onto the grid from firing up coal or gas stations.
"It might not have an effect on overall carbon emissions because we might have to use more carbon intensive power sources to restore supply afterwards," he added.
Mr Hayman said the best thing for climate change would be for people to insulate their homes and get into the habit of turning appliances off at night.
"People ought to focus on general efficiency measures to reduce their energy use overall rather than switch everything off for an hour because that might not have an efficiency effect on the network overall," he said.
James Millar, managing director of the sustainable lighting company Greenled, said when the lights come back on there is "enormous strain thrust upon the national grid".
“Energy companies always retain spare capacity and will continue to produce energy at the same rate throughout the hour-long demonstration which will end up being dumped off the grid with the loss of millions of tonnes of energy due to lack of demand; thereby, rendering all the good intentions of Earth Hour useless – at the flick of a switch,” he added.
But Colin Butfield, Head of Campaigns at WWF, said it was not about saving energy for just an hour but raising awareness.
"Earth Hour is an opportunity for people to show that they care about climate change and want global leaders to take action. Earth Hour is not about saving energy, it’s a positive inspiring event that will show the level of public concern about climate change, and for that reason we will not be measuring energy saved during the hour or reduction in CO2 emissions," he said.