The Amager Bakke waste-to-energy power station in Copenhagen is set to be the ‘world’s cleanest power plant.’ But, despite impressive efficiency — 25 percent greater energy output than the previous plant — and huge improvements to environmental performance, the facility will still produce 107,000 tons of CO2 emissions per year. Rather than shying away from the fact, BIG-Bjarke Ingels Group — the architects behind the project — have commissioned an art piece atop the smokestack to raise awareness of the emissions, in the form of a steam ring generator that produces the circular symbol every time a ton of CO2 is emitted by the plant.