If you're a physicist, I suggest you turn back right now. I'm not, and I don't have much more knowledge than the masses about thermodynamics and physics in general, so this won't sound very interesting to you. As always I'm using my blog as a random thought generator and I decided that after my little post about new technologies, I'd continue in that general area and talk about ways of generating electricity (or "energy").
Up to very recently, I had always thought that there were really only 2 ways of creating electricity: Turning a dynamo, and solar power. You might start to say "wait, there's nuclear, wind power, hydroelectricity"... But all of those - all that are in use today outside laboratories at least, are all just the same: you use some sort of naturally-occurring force to turn a turbine which gives you electricity - it's all about kinetic energy (except solar, obviously).
I remember when I was younger, I thought that nuclear energy was harvested by turning the actual radiation directly into energy through some method I didn't understand. When I learned that it consisted of creating heat, boiling water, and using the steam to turn a turbine, I was crushed and realized how stupidly primitive our energy creation methods really are - imagine, using the awesome power of nuclear reaction - radioactive waste and all - just to heat up water! Later, I kept hoping that someone, somewhere would come up with the real solution, of harvesting the actual reaction into energy directly.
Today, it seems that my earlier thoughts and later hopes are finally turning into reality. This is precisely what prompted this post. So I will outline here the truly different methods I have found of generating electricity.
This is all about spinning a "dynamo" to convert mechanical energy (generally rotation) into electricity by use of magnets (this is where I say "I told you so". The specifics are too complex for me to me). This encompasses more than you think. Hydroelectricity uses water pressure to spin its turbines, wind power does the same with, well, wind. Nuclear energy is used to boil water into steam which, again, turns a turbine. Some fossil-fuel power plants do the same (boil water) while others burn the fuel in generators like your car engine. Even hydrogen fuel cells are the same, burning hydrogen and oxygen and producing water (cleaner, but still the same). Finally, bioreactors use energy stores in biomass (human and animal waste, plants) to create methanol that, you guessed it, is burned to turn an electrical motor.
This is the first energy alternative to "turning a rod" that has been in use in larger scale. Solar power relies on the sun's radiation to "excite" electrons in the panels which become energy (again, layman's terms). Solar power is free, renewable, but not very efficient (around 10% efficiency, they say, though 10% of what I have no idea) and very dependent on weather conditions.
The first time I ever heard about this was when visiting a home depot, as odd as that might sound. I was watching a display for a slow combustion wood stove and on top of it was a small piece of metal with a fan attached to it, with two wires going from the fan motor to metal parts underneath - with no other electronics visible. A clerk told me that it "simply" used the heat from the stove to turn the fan, needing no battery or other energy source... It didn't sink in at the time (took several day of sub-conscious though to realize) that this was another source of electricity. A bit of research shows me that it's called (obviously) thermoelectricity and is created through thermogenerators. Oddly enough, this seems to be only slightly less effective than solar power (5-10%) and I'm surprised we don't hear about it very often. After seeing that fan on the stove I started to imagine all sorts of uses for it, from the heat generated by house roofs to something bigger - using earth's own magma heat to produce massive energy. It looks like we're not there yet, though I hope research is coming along that will soon give us something viable.
Radioisotope thermoelectric generator
Ah, finally, the shining moment of this post. A relatively recent New Scientist article (march 2008) says that it's now possible to use nanomaterials to turn radioactivity directly into electricity. Though according to them (and wikipedia) this has been used in the past, mostly for space probes and satellites. This is my dream come true. As far as I can understand it, you basically place radioactive material inside a capsule of nanomaterial, plug in the wires, and bingo, you have a battery that will last just as long as the radiation does!
Do you know of any other meants of electrical generation i've missed? Please comment on it!