CAMBRIDGE, Mass.—What does it take to pick a winner in the slowly unfolding field of renewable energy? For starters, alternatives to oil must be able to stand up on their own at some point, without a need for permanent government subsidies, said Bill Joy, once a heavy hitter in the information technology industry and now a partner in investor Kleiner Perkins Caufield & Byers's greentech practice.

During a Q&A with Technology Review Editor in chief Jason Pontin at the magazine's Emtech conference Wednesday, Joy pointed out that another key to determining the future of a startup greentech company is whether its approach makes sense intuitively. Investors find new technologies that can displace older technologies because these new technologies are better and make their own case, said Joy. In 1982, he co-founded Sun Microsystems. He went on to serve as its chief technologist for the next 20 years. (Software maker Oracle bought Sun for $7.4 billion in January 2010.)

Despite this pragmatism, Joy has a swing-for-the-fences mentality when it comes to greentech investing. "I'm old enough that I don't want to do the 'me-too' things, such as investing in solar companies that are just ahead of the curve," said the 57-year-old. Instead, he would rather take more risk and fund companies that sink or swim in the short run. "I don't want a 90-percent mortality rate; that's the proper role of the government." Still, he added, "we'd rather create something more substantial by investing in something with greater potential risk. If it fails, we stop."

It also helps to ask the right questions. Joy chose desalination to illustrate this point, asking what it would take to create potable water from salt water for 10 cents per cubic meter (today, it costs about $1 per cubic meter). In considering this problem, he suggests that one builds a figurative box. This box needs to create clean water and salt, because the brackish water that's a byproduct of some desalination efforts is seen as a hazard. How much energy does the box need to do its job? How should this energy be delivered? Electricity or, say, thermal energy? What impact will salt water, notoriously corrosive, have on the box over time? Would a chemical desalination approach be better? The idea is not ready until these questions and others can be answered.

Joy, incidentally, is also well-known for his April 2000 Wired article, "Why the Future Doesn't Need Us," which described his realization that advances in genetics, nanotechnology and robotics will eventually pose grave threats to human survival. Apparently, this fear doesn't extend to greentech. For more on Joy's Emtech comments, see the Twitter feed below.

Image courtesy of Wikimedia Commons