In the late 1980s Boulder. 6MW.8% of electricity power used in the city The payback time for this system is 10 ears,the city is making a pI investment. Through sales of electricity to the electric utility Xcel Energy, this hydroelectric system earned revenue of $1. 7 million for the city in 2004 Figure 5.3 Hoover Dam and lake mead on the Colorado river at the arizona-Nevada border. This installation produces 2080 MW of electrical power as well as storing water for other purposes, including flood protection, irrigation, and recreation (source: Courtesy Bureau of Reclamation/ U.S. Department of Energy) 复旦大学环境科学与工程系 Department of Environmental Science and Engineering, Fudan UniversityFigure 5.3 Hoover Dam and Lake Mead on the Colorado River at the Arizona-Nevada border. This installation produces 2080 MW of electrical power as well as storing water for other purposes, including flood protection, irrigation, and recreation. (source: Courtesy Bureau of Reclamation/ U.S. Department of Energy) In the late 1980s, Boulder. 6MW, 8% of electricity power used in the city The payback time for this system is 10 years, the city is making a profit on its investment. Through sales of electricity to the electric utility Xcel Energy, this hydroelectric system earned revenue of $1.7 million for the city in 2004