In the next few years, the stale, thick heat produced by the London underground will no longer drift uselessly into the atmosphere. Instead, some of it will warm 1,400 nearby homes, cutting heating bills by about 10 percent. Recycling heat is quite common in Europe. Denmark gets roughly half of its electricity from recycled heat, followed by Finland at 39 percent, and Russia at 31 percent. In the U.S., it's just 12 percent.
According to a report by Lawrence Livermore National Laboratory and the Department of Energy, the U.S. wastes more than half of the total energy we produce—mostly as heat, but also as gas, biomass, and methane. Using that waste could reduce carbon dioxide emissions by 17 percent. "It's free energy, essentially," says Brendan Owens, vice president of LEED at the U.S. Green Building Council.
Recycling heat is actually quite simple. For example, new buildings often have condensing water heaters, which use gas burners to warm up water (just as other heaters do) but also capture the heat in the combusted gas that's going out the flue. It happens on a larger scale, too. In 1882, when Thomas Edison built the world's first commercial power plant in Manhattan, he sold its steam to heat nearby buildings. Today, such plants are known as combined heat and power, or cogeneration, plants. Edison's old plant eventually became the massive Con Edison, whose operations today produce 19.7 billion pounds of steam a year. The ArcelorMittal steel mill in East Chicago, Indiana, is another good example. It uses extra blast furnace heat to make steam that then generates electricity for the mill, saving roughly $20 million a year and preventing 340,000 tons of carbon dioxide emissions—the equivalent of taking 62,000 cars off the road.
So why don't we have more projects like these?
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