One of the most popular conservation mantras is the idea that every eco-friendly measure counts, no matter how small and insignificant it seems. Natuurcafé La Port, a coffee shop in the Netherlands, proves this point with a revolutionary new revolving door that harnesses kinetic energy each time it's opened.

Traditional revolving doors are a hotel, airport and department store standby because they are far more effective at keeping out drafts in high-traffic areas than regular doors. The revolving door built by Boon Edam at Natuurcafé La Port goes one step further by capturing the kinetic energy as customers enter and exit the coffee shop.

Natuurcafé La Port's kinetic energy-capturing revolving door generates about 4600 kWh per year, or enough to power a U.S. household for about five months.