There’s energy all around us that's just waiting to be tapped into. Whether it's hot coffee on a cold day, light from the sun, scented candles, waste heat from electronics... there's power to be had! How about we turn it into useful power? Step in the sterling engine. Ever put a tightly filled balloon in the freezer, then come back and see it largely shrunken? Once you bring it back out into a warm room it expands again. Now what if we could use that expanding and contracting for moving a piston... and you've got the general idea. If you heat air, it expands, if you cool it it contracts. It's a very simple idea, for a very simple engine. see the full instructable at: www.instructables.com