I happen to live in a floating house on the Columbia River. Water is about 30 feet deep and flows about two miles an hour. I was toying with the idea of some kind of generator to extract a little power. I'm an electronics tech so I can handle the hardware part.

Then I wondered, is there some kind of chemical reaction from flowing fresh water available? Could put two electrodes of some material in the water and get power out. Just as proof of concept, enough to light an LED would be fine. The idea of no moving parts is appealing.

If you got flowing water, why not use a turbine?

You if the water has a difference in temperature, then you can perhaps do something. Cold material have a different resistance when compared to the same material at another temperature. This property is used in thermocouple thermometers. Try researching about that.

There are several options available, but little to do without moving parts. I've speculated over this matter quite a bit.

You could construct a thermocouple, one area soaked in water for cooling, and the other using ambient temperature or sun heat as the warmth.

You could use a pressure turbine or a water wheel type for a generator.

You could use the water to form a cooling system for you're home.

If you want to do something truly innovative, you could use a bunch of fins that would react to the movement of the water, making abrasive movements on piezoelectric crystals.

I guess its as far as your know how and imagination will take you.

Could you design something based upon the principle of a magnetic flowmeter?
http://www.flowmeters.com/ufm/index.cfm?task=magnetic

The magnetic flowmeter concept could use fixed magnets because current generation is the goal (not accuracy of measurement).

http://www.krohne-mar.com/fileadmin/media-lounge/PDF-Download/Magmeters/HB_MID_e.pdf