Electricity bills could climb by as much as £500 a year as the government seeks to push energy companies towards low carbon power plants, according to analysts.The price comparison website uSwitch said that taxing traditional energy sources such as coal and gas to pay for investment in renewables means that householders could see their annual bills rise by £500 to £1,157.But energy secretary Chris Huhne described the estimates as 'bonkers.'He said that the government's 'best guess' is that 'bills are going to go up over the next 20 years from an average of £500 for electricity household bills today to about another £160.'Energy companies say that the shift towards renewables will require them to spend more than £200bn in the next 20 years.Chris Huhne is expected to unveil his plans before MPs today. He will say that they will help to wean the UK off imported gas and ultimately help to reduce household bills. Writing in the Daily Telegraph today, he said that the government was beginning a consultation that will 'reshape this market more fundamentally than at any time since the 1980s.'A report by the ratings agency Standard & Poors said it expects trends in the European utilities sector to weaken, with investment in green technologies among the factors holding the sector back.British bill-payers already face higher tariffs this winter after NPower, Centrica-owned British Gas and Scottish & Southern Energy have all upped their tariffs.