[M.D. Holloway]

Exactly! Piezoelectric microgenerator devices are composites that convert mechanical energy into electricity. Piezoelectric devices originally took current and convert it into mechanical energy much like the way muscles convert electrical impulses into movement. The problem is that of efficiency and durability though there has many improvements over the past several years.

Another method is hydraulics. I do not know a whole lot about that sort of energy generation method.