Clegg, delivering a major environmental address Wednesday at London's Canary Wharf, said the country's "Big Six" power utilities -- British Gas, E.On, NPower, Scottish and Southern Energy, EDF and Scottish Power -- have agreed to distribute yearly notices to customers spelling out which alternative tariff schemes would best suit their usage profiles.
Some consumers could save more than $150 per year by switching plans and the measure would encourage overall energy efficiency, Clegg said.
"I can announce today that we have secured a landmark deal with the six big energy companies who cover 99 percent of (Britain's) customers, to give customers a guaranteed offer of the best tariff for them," he said.
"Right now, seven out of 10 customers are on the wrong tariff for their needs -- so paying too much. Yet people rarely switch, despite the fact some families could save over ($150) a year. And there are currently over 120 different tariffs, making it very difficult to know where to start."
The requirement, which will become effective this fall, will include a feature in which energy customers will be able to scan a barcode on their bills with a smartphone to get quotes and switch tariffs or suppliers "in a matter of minutes."
He said the government is working to help consumer groups use "collective purchasing power" as a lever against higher bills.
The move comes after British energy users were stunned by sharp price increases.
Average users endured increases of up to 18 percent in natural gas bills last fall. Electricity bills also took a big jump, which the energy companies blamed on rising wholesale costs, the BBC reported.
Clegg admitted that Britain is still dependent on fossil fuels and thus is subject world oil prices -- something the government can't control.
But he declared current austerity measures don't necessarily mean the end of government green energy initiatives, Clegg said the new disclosure requirement demonstrated how "lean times can be green times, too."
"These are the kinds of changes that help people save money, that get us thinking about the energy we use, that promote the kind of thrift that is good for pockets as well as the planet," the deputy PM asserted.
Environmentalists and consumer advocates generally praised the move but some dismissed it as not addressing the real problem -- continued reliance on "dirty" fossil fuels while cutting funding for renewable energy projects
Paul Steedman, a spokesman for Friends of the Earth, which claims more than 2 million activists in 76 countries, said that while the disclosure requirement is fine, London at the same time is supporting the building of more natural gas-fired power plants.
"Clegg's admission that we can't control world energy prices points to the real problem for energy customers -- that just six big energy firms have us hooked on dirty, expensive, imported gas," he said.
"Rather than papering over the cracks of our broken energy system we need ministers to make our homes more efficient and to switch to clean British energy from the wind, sun and waves we have in abundance."
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