A government-led program to encourage energy efficiency could reduce growth in electricity demand by 20 to 47 percent in the U.S., according to three-year report by the Energy Department’s five laboratories. The amount of energy savings would depend on the price of new energy technologies and how aggressively the feds promoted efficiency in buildings, factories, and appliances. The savings would be the equivalent of 265 to 610 300-megawatt power plants, taking a big chunk out of the 1,300 new plants (more than one a week for the next 20 years) that Vice President Dick Cheney says are necessary. The Bush administration has not publicized the report, which was completed just before President Bush took office, instead drawing attention to the work of economists who are skeptical of conservation at the Energy Department’s Energy Information Agency.