THE ENERGY ECONOMY Since transporting water eats up so much electricity, developing ways to recycle the water that goes down the drain could yield big energy savings. The nation’s model for this kind of innovation is Las Vegas. “We reuse virtually 100 percent of our wastewater,” , the district has modernized its water reclamation system, which now returns 70 billion gallons of treated wastewater annually to Lake Mead, the source of 90 percent of Las Vegas’s water. With the nation’s water infrastructure nearing the end of its design life, now is the time to build a more energy-efficient system. “We need to avoid pumping water over long distances and focus on systems that produce water for reuse where it’s generated