The latest addition to the renewable energy vanguard is not clean at all. Dirty water -- specifically warm and hot wastewater from shower drains, dishwashers, and laundry -- is a surprisingly powerful source of energy, and cities around the world are taking notice.
At National Geographic, Rachel Kaufman explains the technology:
The technology is simple. Wastewater, which consists of what gets flushed down toilets but is mixed with millions of gallons of hot water from showers, dishwashers, washing machines, and more, maintains a fairly constant temperature as it travels through sewers to the treatment plant—typically about 60°F (15.6° C), though this varies by geography and season.
In a sewage heat recovery system, a heat pump is used to capture the warmth of wastewater and transfer it to the clean water stream that is entering homes and businesses. .. [T]he warmth of the sewage water helps heat the water that is then used in showers, washing machines, dishwashers, or even in radiators to help heat buildings.
From Vancouver and Oslo to Chicago and Tokyo, cities are installing heat recovery systems that capture the energy potential of wastewater.
The first big wastewater heat recovery system in North America is in Vancouver, British Columbia, providing 70 percent of the energy needs to the Olympic Village, a green community developed for the 2010 Games. The waste energy facility features finger-like exhaust stacks peaking above Cambie Bridge, topped with LED lights that glow blue at times of low energy use and red when demand is high.
With sewage heat recovery systems established in Oslo, Tokyo and Beijing, U.S. cities like Seattle and Chicago are experimenting with the technology too.
"Not a lot of people shake your hand when you're in the sewage business," jokes Lynn Mueller, president of International Wastewater Heat Exchange Systems, based outside Vancouver. "But everybody I've talked to in the past two years recognizes the amount of heat that goes down the sewer. It should be recovered."
(via National Geographic)
Photo: The False Creek Energy Centre in Vancouver is the first big system for wastewater heat recovery in North America. (Ausenco Sandwell / City of Vancouver)