Daniel Rosen wants to make clear that his solar energy startup is not a traditional energy company. "Solar companies used to be about hardware," says the 26-year-old cofounder and CEO of San Francisco-based Solar Mosaic. "We're an online marketplace."

Rosen was among dozens of twentysomethings who congregated at New York University this January for the second "Cleanweb Hackathon"—a weekend forum for would-be entrepreneurs to demonstrate the role that mobile apps, social networks, and Web software can play in improving how we use energy and natural resources.

The term "cleanweb" was coined by San Francisco-based venture capitalist Sunil Paul and is meant to draw a distinction from cleantech, the high-risk, capital-intensive industry led by battery startups, biofuel makers, and makers of wind turbines and solar panels.

The cleanweb, by contrast, is all about using inexpensive information technology to change how the world consumes energy. Paul, an investor with Spring Ventures who has invested in Solar Mosaic and helped organize the hackathon, calls the cleanweb "the most powerful lever" available today to entrepreneurs hoping to solve environmental and ecological challenges. 

During the weekend competition, teams set out to show how data available on the Web can help. One group of programmers combined data from New York City's government with Google Maps to build a website tracking which municipal buildings emit the most greenhouse gases. Another team created a comparison-shopping engine that ranked products sold on Amazon.com according to their energy efficiency.

Worry over the environment, and a desire to challenge the fossil fuel industry, is what is leading some people to join the cleanweb movement. "What's motivating me is the climate change problem," says Zak Accuardi, a recent graduate of Columbia University. "People are ignoring it, and I'm trying to figure out the best way I can effect change."

Because the field is so new, there's still a chance to strike it rich, promoters promised. Dave Graham, an investor with Greenstart, which runs an incubator in San Francisco for cleanweb startups, told the coffee-swilling hackers that "you don't have to start the next Facebook to make a boatload of money."