In Chicago, for example, two aging coal plants shut down after Mayor Rahm Emanuel threatened them with an ordinance requiring they clean up emissions.

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It will not just clean up its own industrial act (cutting emissions 1% over the next seven years, when emissions would otherwise have risen 40%) but also get more deeply into the business of selling eco-friendly devices to other companies.

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Under an industry agreement with regulators, your company agrees to run the emissions through a costly clean-up device.

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Now plants have to clean up if they modify their facilities and increase annual emissions.

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Some believe that retrofitting ships with equipment like "scrubbers" that remove harmful emissions from vessels could help the industry to clean up its act.

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