As part of the preparations to kick of Greener by Design 2009, happening this week in San Francisco, we've been posting podcast interviews with many of the top-notch speakers who will be sharing their expertise at the event.

But until now, we haven't talked about the attendees at the event -- specifically, the four Net Impact student members who were the winners of a cool contest we organized with Steelcase and Net Impact.

The contest, the Steelcase Sustainable Design Contest, challenged the student members of Net Impact, a networking organization that works to promote socially responsible business for entrepreneurs and students, to develop a socially or environmentally beneficial business idea, product or service. The entries were judged by Net Impact, GreenBiz.com and Steelcase, and out of all the final submissions three ideas, submitted by two individuals and a team of two, were chosen.

"Student changemakers and entrepreneurs are an active part of the Net Impact network," said Krista Van Tassel, the director of communications at Net Impact, who worked closely on the scholarship competition. "We were thrilled to partner with Steelcase and GreenBiz.com to develop this special opportunity to not only highlight student thinking around sustainability and design, but also showcase some of our members' best ideas on new products that unite social and environmental value to sustainability-minded executives at Greener by Design 2009."

Dave Berger's solar-powered lighting system. Click here for a full-sized image.

In no particular order, the first winner was submitted by Dave Berger from New York City's The Cooper Union for the Advancement of Science and Art. Berger has developed and put to use in Ghana several solar-powered lighting systems that have been designed to be locally manufactured and repaired, affordable to build, and long-lived.

Berger plans to bring local entrepreneurs on board with selling the "solar lighting business starter kit," which will help launch "social businesses," a term popularized by Nobel Prize-winning microfinance pioneer Muhammad Yunus to describe organizations designed to help people while also turning profits for entrepreneurs. Berger's lighting kit, consists of a solar charging station and an array of portable lanterns, as well as the required tools and assembly instructions, and can essentially be packaged in a duffel bag.

A visualization of John Dreher and Mike Norelli's MC Shared energy monitoring system. Click here for a full-sized image.

The next winning idea was submitted by John Dreher and Mike Norelli from the Massachusetts Institute of Technology. Their idea, MC Shared, is a human-centered energy monitoring that aims to encourage and make it easy for Americans to be more energy efficient at home.

Dreher and Norelli looked at ways that harnessing the power of social networks can lead people to do good. After interviewing people who either had or considered buying home energy meters, the two students found that products currently on the market are both too expensive and focus on practical motivation rather than emotional motivation to encourage people to change their behavior.

Their resulting design sends home energy use information through the owner's internet connection rather than a dashboard display, which brings the sales cost as low as $20. The system also allows users to share their current energy use through existing social networks like Facebook, encouraging a race to the top for home energy efficiency amongst users.

A detail from Edgar Rudberg's Community Cactum Rainwater Collection System. Click here for a full-sized image.

The final winner of the Steelcase Sustainable Design competition is Edgar Rudberg, from the University of Minnesota for his "Community Cactum Rainwater Collection System."

The collection system is a kit that aims to help water-deprived communities collect and store rainwater. Using a special catchment system, Rudberg's design captures the rainwater in a tarp, directing it to a central drainage whole, where the water is filtered and stored in a heavy-duty storage bladder, which can fit inside a 55-gallon drum and be fitted with a spigot to dispense the filtered water.

All four students will be attending this week's Greener by Design conference in San Francisco; we'll be bringing you highlights from the event all week -- visit GreenerByDesign.com for the latest updates.

To learn more about Net Impact's work, visit NetImpact.org, and for more on Steelcase's work on sustainable design, visit Steelcase.com.