For many years, traditional windmills were the fastest way to pull water from the ground, and they still pump water into stock tanks in pastures where cattle and wildlife drink. Many farmhouses also used wind-powered generators for household lighting and electrical needs until the federal government created the Rural Electrification Administration in 1935 to provide farms with inexpensive coal-fueled electric lighting and power. By the early 1970s, about 98% of all farms in the United States had electric service. In 2010, Duke Energy completed a 34-tower wind farm spread over 6,000 acres northwest of Burlington. Each tower stands 260 feet high, each blade is 113 feet long, and all 34 towers together produce 51 megawatts with 25 miles per hour wind, enough to power about 15,300 average-sized homes. Because wind energy cannot be stored for later use, it supplements conventional power sources, and electricity from the nearby turbines is used by local electricity cooperatives through an electric power transmission network.