The Minto Wheel is not a new idea. This simple yet clever heat engine was invented by Wallace Minto, and first presented to the public by Popular Science, Scientific American, Mother Jones, and other sources back in the 1970's. Simply put, the Minto Wheel is a an hermetically sealed ultra-low maintenance device that converts small temperature differences into useful mechanical torque (see links below). Its operating principle somewhat resembles that of a Stirling engine, but the Minto Wheel is more low-tech and durable, and probably more reliable over the long-term. Initially, some hope existed that it could find useful applications such as using solar heat to pump water in third-world agricultural projects. But due to some early technical problems and misunderstandings (and the generally low interest in alternative energy technologies), it never caught on. A year or two ago, the MythBusters television show built and tested a Minto Wheel, but did a surprisingly poor job building their prototype, and hastily concluded that it was "busted" (a rare blunder by the otherwise praise-worthy MythBusters team). But despite all the unfairly negative reporting over the years, individual experimenters continue to try to optimize the device. Follow the links below to learn more about the Minto Wheel.
Video of a working Minto Wheel:
http://www.youtube.com/watch?v=-fUlKBH1sY8
Original diagram and description appearing in Scientific American:
http://www.amasci.com/freenrg/minto.html
Yahoo group specializing in the Minto Wheel and related heat engines:
http://tech.groups.yahoo.com/group/MintoWheel/