Essen's experiment: can going green revive a post-industrial city economy?

The German city is working to shake off the coal dust of the industrial Ruhr, but will green tourism be profitable enough to regain its former economic strength?

The shores of Baldeneysee, a ribbon of a lake that feeds into the Ruhr river near Essen, are busy. Schoolchildren cannonball into the water as sunbathers sit on beach chairs, nurse their beers and watch the paddleboarders pass by.

It wasn't always like this. "When I was a little boy in the 70s, every morning we used to sweep coal dust and ash off our window panes," recalls Frank Martini, an Essen resident. "Emissions from the furnaces and ovens of coal and steel industries stained our clothes left outside to dry."