A key climate change bill now being considered by US Congress would only modestly raise annual energy costs for families, far less than some industry estimates, a federal study said Tuesday. The estimate by the Energy Department's Energy Information Administration (EIA) said average electricity prices would increase by just three to four percent by 2020, compared to current practices. The EIA said the bill 'increases energy prices, but effects on electricity and natural gas bills of consumers are substantially mitigated through 2025 by the allocation of free allowances to regulated electricity and natural gas distribution companies.' However, it cautioned that 'both wholesale and consumer energy prices rise quickly in the first four years, level off for the next 10 years and then sharply rise for the last five years.' EIA also found that gasoline prices would increase on average by 20 cents per gallon by 2020 and by 35 cents per gallon in 2035. But clean vehicle technology could offset those costs. 'The evidence is now overwhelming that this clean energy legislation is both affordable and effective,' Democratic Representatives Henry Waxman and Edward Markey, who co-authored the climate change bill, said in a statement. 'American clean energy will grow substantially, and so will clean energy jobs that can't be shipped overseas.' House Speaker Nancy Pelosi also hailed the report's findings, saying they 'confirmed that clean energy is a good investment for our economy and for our energy security.' The study's findings were consistent with those of the Congressional Budget Office and the Environmental Protection Agency. But the American Petroleum Institute, a trade group for the oil industry, has said that the bill would cost an average family 3,300 dollars per year by 2020 and cause gas prices to jump 74 percent by 2035. 