More than a century after electricity first flowed to the city, a major change could come to how New York is powered. Officials are looking to require that electricity in city buildings and street lights comes from renewable sources, like wind or the sun. NY1's Josh Robin filed the following report.

We're the city that never sleeps, but those bright lights and energy-draining air conditioners are blackening the skies.

City Hall has long tried to clean up pollution from power plants. Now, officials are flipping a new switch: requiring any power the city gets be entirely green.

"Wind power, solar power and water power. Truly renewable sources," said First Deputy Mayor Anthony Shorris. "To do that, that's a very complicated set of changes."

Complicated because it's at least 4,000 buildings, plus all those street and traffic lights. In all, it's one-tenth of the power used in the five boroughs, costing $600 million a year.

If the city plugs in, though, it may not just cut its own greenhouse emissions.

"This isn't involving the private sector, although at some point, what we hope is that by us taking this kind of leadership role that we will catalyze the market in the area," said Nilda Mesa, director of the Mayor's Office of Sustainability.

And perhaps reduce dependency on Westchester's Indian Point nuclear plant while sparking green plants within city limits.

A windmill at a Brooklyn recycling plant is one of the few ways renewable energy is produced here.

Right now, only 1.5 percent of the city's energy comes from renewable sources, but that's changing with a boost from the top of City Hall. Literally, the top of City Hall.

Solar panels are up as of April. Turbines sank into the East River several years ago.

Still, there's a limit to how green power plants here can be. Average wind speeds are only 5 mph, and there aren't exactly ideal conditions for big solar farms. So officials say power could come also from outside, like waterfalls or windier areas. But that also poses problems.

"There's a limited amount of transmission capacity," said environmental law expert Michael Gerrard.

Gerrard says bottlenecks could grow in lines leading to the borders, unless the city and state act.

"That's not always popular, and it could take years to get the approvals for that," he said.

Officials hope the greening is complete within 10 years. In the meantime, it is boosting efficiency and turning to others for more illumination.