I’m wondering what are some options to get free or efficient source of energy? I am looking for a cheap or recycling options. Some I had in mind are

Solar Sterling Engine Generator – I don’t know how or where to get the sterling engine
Wind Turbine Generator – We don’t really have that much of air
Magnetic Generator – It uses some neodymium magnet to turn and convert it to power the generator.
I like the idea, but i haven’t seen an actual working device. most I’ve seen are just either theoretical or a small prototype.
Solar Panel – Too expensive and not efficient, just my opinion though

Please let me know your Ideas. Thanks!