This are often used in conjuncture with Capacitor for short term but regular use and to trickle charge batteries for long term but irregular use
The potencial of these have yet to be uncovered. They can be made by a wide range of materials
SEG Magnetic Generator
These generators work on a whole new level of electricity, given that they use free electrons that travel without atom nuclei thus not generating heat but actually cools instead
Though complex, they are very effective and ever lasting. Due to its unconventional use of electrons, they can corrode and also do wear down