Here's another excellent science project from Dan Rojas at the Green Power Science [YouTube Channel] together with some great viewer suggestions from the video's comment section.
I use dry grass clippings to make bio char, you heat a metal paint can with a lid. You must have a way for the gas to escape! This stuff is good for the garden. The down side is that it smells worse than anything you can imagine.
Try it with wood chunks and you will find the best BBQ charcoal you ever used.
I don't need to use the underwater method just heat things without much air and you get charcoal and not ash. -- buttkracken
The escaping gas is the most useful part of the process! That gas is commonly called syngas. It's a mixture of methane, hydrogen, carbon monoxide and water vapor, along long chain hydrocarbons--tars.
What you want to do is pass that gas through another cool container to condense all the tars out of it, then use it to run a normal piston-cylinder engine. Like a lawn mower or a small generator! -- cavemanboborj
Science is a wonderful thing if one does not have to earn one's living at it. -- Albert Einstein