Two engineering researchers at the University of Wisconsin at Madison have developed a new in-shoe technology that can generate electrical energy as people walk. An insert for shoes uses the thermodynamic power that is generated with each step a person takes; they think that eventually a two-hour walk could charge a cell phone. The two students, Tom Krupenkin and Ashley Taylor, have created a company called InStep NanoPower to develop the concept, hoping to have it available for sale in two years.