Production of natural gas locked in shale will double by 2035, helping the U.S. become less reliant on imported energy, according to a federal agency forecast.

The Energy Information Administration’s annual long-term forecast “shows the growing importance of natural gas from domestic shale gas resources in meeting U.S. energy demand,” Richard Newell, the agency’s administrator, said today in a statement accompanying the report.

The Annual Energy Outlook predicts imports will meet 18 percent of U.S. demand by 2035, down from 24 percent last year. Higher prices will spur fuel production, including natural gas, oil and coal, the agency said. Tougher energy-saving rules, such as fuel-economy mandates for new cars, and a boost in biofuel production from crops such as corn also will make the U.S. less reliant on imports by 2035, according to the forecast.

Overall U.S. energy consumption will jump 21 percent by 2035. Coal will remain the “dominant energy source for electricity generation,” although more natural-gas fired plants will be built because of higher supplies of the cleaner-burning fuel, according to the outlook.

The agency forecasts construction of five nuclear plants by 2035, contributing to a 10 percent increase in electricity generated from atomic power. The share of electricity from renewable sources such as hydroelectric dams and solar panels will rise to 14 percent in 2035 from 11 percent last year, according to the outlook.

Gas Reserves

This year’s outlook more than doubles the estimate of U.S. technically recoverable reserves of natural gas from shale, a type of sedimentary rock, to 827 trillion cubic feet from 347 trillion cubic feet. New technologies that let natural-gas producers drill horizontally and fracture the rock formations with injections of water, sand and chemicals account for the increase, the EIA said.

The agency raised its 2035 projection for natural-gas production 25 percent from last year’s outlook “as a result of greater supply availability from shale gas plays,” the EIA said.

Average annual Henry Hub natural-gas prices, in 2009 dollars, are predicted to be $4.81 per million British thermal units in 2015, $5.18 in 2020 and $7.19 by 2035. Last year’s forecast for prices in 2035 was $8.88 per million Btu.

The cheaper price will drive up the use of natural gas as a fuel for generating electricity, at the expense of coal and renewable sources such as wind turbines, the EIA said. Natural- gas electricity generation by 2020 is 29 percent higher in this year’s outlook. Gas-fired generation by 2035 is 17 percent higher than last year’s forecast, the EIA said.