[Editor's note: In this exclusive excerpt from Joel Makower's new book, "Strategies for the Green Economy," offers a look at just a few of the innovative companies and thinkers that are emerging in the new green economy, changing the way industry creates everything from clothing to housing to solar energy. You can read a previous excerpt here.]

The advent of the green economy coincides with a new era for entrepreneurism. Unlike, say, Ben & Jerry's, today's promising young green companies are less likely to be influenced by the war than the Web. Today's entrepreneur has been chastened and emboldened by the successes -- and excesses -- of the Internet revolution. Indeed, many green-economy entrepreneurs are dot-com refugees, flush with cash, connections, and a can-do mind-set. They bring their innovations in business strategy, such as the notion of turning products into services, of customers as "members," of networks as marketplaces.

One of countless examples is SolarCity, founded by Lyndon and Peter Rive, two brothers who previously started a software company they sold to Dell. The Silicon Valley company became a fast-growing phenomenon by creating a residential solar purchasing program that encouraged neighbors to join together to receive special group pricing incentives on solar installations.

It's a classic dot-com play: Break through the barriers of the incumbent business mind-set, in this case by using the power of human networks to do viral marketing on the company's behalf, thereby short-circuiting the marketing and sales cycles. SolarCity has attracted major investors, including Elon Musk, the brains behind PayPal.

And then there's Sungevity, another solar company, this one founded by two brothers-in-arms, Danny Kennedy and J.P. Ross, both ex-Greenpeace activists turned solar entrepreneurs. Their company similarly brings dot-com smarts to the relatively staid world of solar energy. It works like this: Simply enter your address on Sungevity's Web site. Within 24 hours (more or less), you'll get a complete analysis of your home's solar potential, including a proposal for three different types of solar systems and a picture of what your house will look like with each. You'll also get complete financial analyses of the three systems, a contract, and all the paperwork.

All this used to take at least two site visits, usually over several weeks. Sungevity uses Web and mapping technology (similar to Google Earth) to calculate your home's solar profile -- how much sunlight it gets, whether that sunlight is shaded in ways that negatively affect its exposure to the sun, and other factors -- and automates a heretofore heavily manual, paper-based process. Such a smart, automated system seems like a no-brainer -- but then again, no one has done it previously.

Another smart, automated player is mkDesigns, founded by Michelle Kaufman, an architect who previously worked with Frank Gehry and Michael Graves -- renowned architects known for out-of-the-box thinking. The company has created affordable prefabricated green housing that breaks the mold for how people think about either. mkDesigns creates custom homes built in factories, which sounds like an oxymoron but actually makes a lot of sense. By building the core of each home in a controlled factory environment, the company is able to reduce costs, improve quality, and take advantage of economies of scale. On site, the homes are customized -- they can be one story or many, small or large, even sizable multifamily structures. You'd never know their factory origins.