Semiconductor-based lighting could cut the energy used by lighting in half, says the U.S. Department of Energy. Because lighting accounts for about one-fifth of all electricity used in the United States, that could add up to some US$98B in energy savings by 2020. DOE figures just replacing the country's 60W bulbs with 10W LEDs would save enough electricity to power all of Las Vegas for a year – twice. Indeed, the government is so keen on the idea it is offering up to US$20M in prize money to developers of viable commercial fixtures.