Hollywood stars Leonardo DiCaprio and Mark Ruffalo have teamed up in a bid to widen access to clean energy.
The actors launched "100%", a campaign aimed at making energy from renewable sources available to everyone - and making it affordable.
DiCaprio has spent much of the last few years supporting environmental and animal conservation efforts.
At the event, the Titanic and Wolf of Wall Street star said the clean energy movement was no longer about politics, but humanity.
The event was held at a community garden in New York City.
Musicians and dancers entertained the crowd while a solar-powered pizza truck provided food. A solar-powered mobile phone charging station was also available.
This event comes on the heels of Pope Francis' urgent plea on Thursday for the world to clean up the environment, likening it to a moral issue.
Meanwhile, the US government is issuing new rules intended to improve fuel efficiency for medium and heavy-duty trucks and to cut pollution blamed for global warming.
The Obama administration's proposed standards are expected to lower carbon dioxide emissions by about one billion metric tonnes, cut fuel costs by about 170 billion dollars (£107 billion) and reduce oil consumption by up to 1.8 billion barrels over the lifetime of vehicles sold under the rule.