Some time ago, somebody invented the steam engine. The steam engine works by heating water in an airtight container to make steam. The steam is massively expanded water, and the result is lots of pressure. Once you have lots of pressure you bleed a bit of that pressure intermittently into a piston, and the piston gets pushed. Connect that to a crank, and you have rotational motion, and an industrial revolution. You also have lots of factory workers being blown up in hideous, explosive accidents, with all the screaming, and loss of productivity that goes with being killed.
Later someone invented the internal combustion engine, and the turbine engine. These run on fossil fuel. They had a pretty good run until somebody discovered it was making us sick and killing everyone.
The turbine engine is a big thing you tend to stick to the ground in a power plant and make electricity. That way the factories could all have much safer working conditions where hardly anyone ever got blown up, but it also kills the earth a bit. Just a little every day. And sometimes some of them explode anyway. That's not so good, because some use uranium to make the heat, and that never ends well.
Anyway...
The internal combustion engine tends to be used in portable things like cars, because they pack such a lot of punch for such a small weight in fuel. They also kill the world, just a little bit each day, and sometimes explode, and sometimes just mash into each other, and mash into other things that tend to be near roads. They do a lot of mashing.
The main advantage with the turbine, and internal combustion engines, is that they spread out the damage. Just one or two people from any given factory at any given time get killed by them rather than taking out half the factory's workforce all in one go like a steam engine disaster might. The mayhem and disaster is spread out so that each factory takes just a small share of the disruption to productivity. Except perhaps with the uranium stuff. I think that's why Australia is shipping all our uranium to distant countries. To move it as far away as possible.
Anyway...
A Stirling engine on the other hand is a slightly more peaceful beast that doesn't really do a lot, but what it does, it does pretty thoughtfully. Historically it fits between the steam engine and the stuff we use today (2013, just in case someone reads this in 40 years). The Stirling engine is an engine that uses the difference in heat between two of it's bits of kit, to make stuff spin around without all the explosions.
There.
That's the design description out of the way.
It's very safe, because it doesn't have a pressurised container. It needs a source of heat, but that can be solar, or waste heat from something else. Rotting compost, your wireless router, whatever. They are not a very powerful engine, which is why the internal combustion engine took over, and they are not very responsive to sudden changes in desired power output. That's also why the internal combustion engine took over. And they are not very powerful... Internal combustion engine blah blah blah.
So...
The most beneficial thing as far as I'm concerned is that they wont blow up and kill me.
They're not very useful. But that's not going to stop me making one.
The kind of thing that will stop me making one, is more likely to be that I have no idea how.
I've never made an engine before, and have also never met anyone who has, but it turns out they are a pretty simple kind of beast, and with a bit of luck, wire, string, and the total combined wealth of human knowledge stored on the Internet, I might be able to make one.
People are very clever, and there are some really helpful ones out there that are willing to help me.
I'll be trying to make a very small Stirling engine that runs on the power of a small candle, that will do no work, but will hopefully work.
120 Things in 20 years - Stirling engine - It might go round and round.
