Wave Power
Hinged cylinders anchored in the seafloor are pushed by waves, turning onshore turbines that create electricity (Orkney, Scotland)
Underwater Turbines
Turbines seated on the seafloor or estuary bed are spun by daily tides, generating electricity (New York City)
Storm-Surge Gates
Open gates in rivers, estuaries and canals close when storm surges are expected, to protect low-lying and subterranean infrastructure (Rotterdam; London)
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Smart Parking
Digital parking meters tell mobile-phone and navigation apps when a space opens up, reducing traffic caused by drivers trolling for spaces (San Francisco)
Congestion Pricing
Charging drivers higher rates to drive in busy neighborhoods eases traffic (Stockholm; Singapore)
Solar Hot Water
Rooftop tanks, heated by the sun, provide domestic hot water instead of furnaces (Rizhao, China)
Underground Parking
Subterranean garages near commuter destinations eliminate the need for cars to surface (Paris)
Underground Transportation
Commuter trains, subways and primary roads run underground in massive tunnels, freeing the ground level for easy, clean bike and pedestrian traffic (Portland, Ore.)
Solar Films
Photovoltaic sheets on south-facing building facades generate electricity (Berlin)
Bike Racks and Lanes
Ample bike lanes and racks encourage more people to ride instead of drive; they also promote fitness (Minneapolis)
Solar Power
Panels generate electricity instead of power plants and also shade rooftops to lower a building’s cooling needs (Redlands, Calif.)
Satellite Irrigation
Satellite control of park and lawn irrigation systems cuts water consumption and pumping power (Los Angeles)
High-Efficiency Windows
Superinsulated windows quadruple the thermal performance of double panes and can be made from the glass in existing windows (Empire State Building, New York City)
Three-Bin Recycling
Requiring businesses and homes to separate trash, recyclables and compost spares landfills; collection charges drop as trash drops (San Francisco)
Carbon-Sequestering Concrete
Construction material made locally with carbon dioxide that is exhaled by power plants could reduce greenhouse gas emissions (Under development)
Low-Flow Appliances
Water-saving toilets and showerheads installed in buildings save millions of gallons annually (Austin, Tex.)
Hybrid Taxis
Large portions of taxi fleets converted to hybrid vehicles reduce air pollution and greenhouse gas emissions (San Francisco; New York City)
Vertical Farms
Food grown indoors could reduce fertilizer and freshwater use, shorten transport and recycle gray water otherwise dumped by treatment plants (Under development)
Storm-Water Pricing
Taxing property owners on the volume of storm water that runs off their property promotes retrofits that reduce wastewater volume at treatment plants (Philadelphia)
Green Roofs
Rooftop vegetation insulates buildings against heat and cold and absorbs storm water (Chicago)
Underground Utilities
Tunnels dedicated to carrying electricity, water, cable television and broadband Internet minimize damage from storms and make repairs easier (London)
LEED Neighborhood
Residential and commercial construction done across a city region to the highest green, or Leadership in Energy and Environmental Design (LEED), standards saves energy, materials and emissions (Rockville, Md.)
White Rooftops
Rooftops painted white reflect heat, lowering a building’s cooling cost and a city’s heat buildup (Washington, D.C.)
Sewage-sludge Incineration
Solid waste extracted from sewage at treatment plants is burned to make electricity (Nashville, Tenn.; Buffalo, N.Y.)