This is something i spoke to some friends to about, and we all agreed it could be done in theory, but that in reality it would end up blowing up because people drink and forget about things at a bbq. besides who wants to worry about a steam engine while cooking.
So im making one anyway.
The main body of the thing is an old beer keg i had given to me, the boiler is made from an old fire exstinguisher i got from god knows where. was pretty old-ish. it had a service number to call in sydney, that was only 6 digits long. so whenever that was.The idea is pretty simple.
Use some of the excess heat a bbq produces to generate a little steam. That can either run a turbine to make some electricity or mechanical power that can be used for other things. Or both.
The boiler is pretty simple. the brass cylinder on the outside of the keg is really just a resevoir. it has a pipe that runs into the keg where the fire sits, and back out into the resevoir. The water boils, creates steam.
The steam comes out the top of the resevoir, back into the keg, gets heated again, then onto the turbine.
From the turbine (currently being constructed) i will have a small amount of electricity and mechanical power to have a light, and a rotisserie.
There will be other things of course, but for now they are just ideas and will need a little consideratioin before i commit to them.