A generator for converting mechanical energy or hydropower or wind energy into electrical energy is disclosed. The generator includes a first member and a second member in contact with the first member to generate triboelectric charges. The second member rolls against the first member to generate a flow of electrons between two electrodes. Another embodiment of the generator includes two electrodes, and a member in contact with the two electrodes to generate triboelectric charges. The member rolls against the electrodes to generate a flow of electrons between the two electrodes.
STATEMENT OF GOVERNMENT INTEREST
 This invention was made with government support under agreement No. DE-FG02-07ER46394, awarded by the Department of Energy and under agreement No. CMMI 0403671, awarded by the National Science Foundation. The government has certain rights in the invention.