small electric generator

[MikeKowal]

Hello all:

I was wondering what is the most efficient and practical way to make a small electric generator for turning compressed gas into electricity. Gas turbines are much too large for the small project I'm trying to build.

Should I use an electric fan for the turbine? This is the cheapest, easiest way but I wonder how efficient it is.

What about a piston/camshaft set up. Pressurized air could be introduced into piston and allowed to expand, moving the piston.

What about using a model plane mini gas turbine and turning it into a little gas turbine? I think this would be the most efficient design, but the hardest to build.

Please offer me your input, or ideas for websites for me to visit.

Thank you.

Mike

[BoulderHead]

MikeKowal, Welcome to PF !!!
I was wondering what is the most efficient and practical way to make a small electric generator for turning compressed gas into electricity.I don’t know but take it that you are not worried about the efficiency of compressing the gas (air?... I think maybe 15%, but don’t hold me to it)?
Should I use an electric fan for the turbine? This is the cheapest, easiest way but I wonder how efficient it is.You mean like a 12-volt automotive type fan? Yeah, probably it would be easy but not very efficient as the blades on those things are made to drive the air, not be driven by the air.
What about a piston/camshaft set up. Pressurized air could be introduced into piston and allowed to expand, moving the piston.This sounds pretty slick. Is this what led you to;
What about using a model plane mini gas turbine and turning it into a little gas turbine? I think this would be the most efficient design, but the hardest to build.These are little two-cycle engines aren’t they? My gut is telling me that a 4-stroke might be better, but even if it were I don’t know where you could get such a tiny engine.

[edit]
Oops,
I think my gut was wrong, thinking we were compressing.

I think I once saw a model airplane that you charged with compressed air and the air would push a piston which turned a crank that spun the propeller. I’m now thinking to try a hobby, or toy store, and look for such a thing. Replacing the propeller with a small DC motor might just do the trick.
Good luck

I'll see if I can find you a link or two.

[BoulderHead]

Whoa, this isn't what you had in mind, but it sure is a piece of work;
http://www.netaxs.com/~mhmyers/turbine.html

Interesting info on propellers;
http://www.eskimo.com/~smallnet/JoeArticles/Propellors.html

Getting warmer now;
http://www.keveney.com/co2.html

I can't believe I actually found one;
http://www.paramountzone.com/airhog.htm

Get after it with a coke bottle;
http://www.ranney.com/~mjr/photos/airbottle/

Discontinued??? what a bummer!;
http://www.amazon.com/exec/obidos/ASIN/B00004TCQU/dealtime-dag/102-7950659-3790553