Swedish Architect and Urban Strategist, Måns Tham, has proposed 'Solar Serpents' as a way of turning freeways into urban powerplants! With solar-technology and a narrative design, the freeways re-emerge as contemporary structures...
And, yes, he proposed this back in 2010, but I have only just stumbled across the idea - and Solar Serpents are such a beautiful and elegant solution to both the ugliness of freeways and the need to generate more renewable energy, that I just wanted to share it!
Måns Tham's other work is pretty amazing too!