Levant Power, which has a shock absorber that turns bouncing into electric power, won the MIT Energy Prize.

The company's GenShock takes kinetic energy (i.e., movement) and converts it to electric power, which in turn can be used to run subsystems on a car. The company estimates Walmart could save $13 million a year if it equipped its massive fleet of trucks with them. Overall, the GenShock improves gas mileage by 2 percent to 10 percent.

The competition is national and not just confined to MIT students. The contest gives startups visibility as well as cash to get things moving. The winner of the energy prize also goes on to compete in the business plan competition with a $200,000 grand prize. Last year's energy prize winner was FloDesign, which has a wind turbine that funnels air into the turbine the same way jet engines funnel air into themselves.