After seeing models of gasifiers in action, my son wanted to build one. Gasifiers are specially designed containers for burning wood in.
When wood burns, it releases gases like carbon monoxide, methane, hydrogen and violate organic compounds which create ozone when exposed to sunlight. These gases are bad for the environment and for us to breathe in.
A gasifier however, is designed to trap these gases and burn them as well. It is a very efficient use of energy as you have a fuel source (the wood), and a secondary fuel source (the gases released).
Furthermore, with the burning off of these flammable gases, you are engaging in clean burning of wood and reducing the impact of wood fires on the environment.
Our plan was to make a compact, portable gasifier from different size Milo tins and boil water on it for Milo, using only twigs, grass and leaf litter. The challenge was to see if we could produce some hot Milo in an area where there was no wood for a proper campfire.
Jets of flame from secondary burning of gases
The coolest thing about the gasification process is you can actually see the jets of gas being burned off within the gasifier. We were expecting to see just a fire in a small container and were surprised to observe the fire behave differently.
Instructions for the process:
Step 1: Remove the paper from the Milo tins. You will need a 1kg tin and 2 750g tins. (The second 750g tin is for the pot holder). If you haven't already eaten all the Milo, put it in another container and start marking 2 rings of air holes around the bottom of both tins and one ring of holes at the top of the 750g tin. You also need lots of holes in the bottom of the 750g tin, making the bottom like a sieve. We made some holes larger than others for better circulation.
Step 2: Use a hole punch to dent the tins where you marked them so the drill does not slide when drilling. This step is important if you have kids involved in the project. Alternatively, you can use a bigger size hole punch to just punch holes through.
Step 3: Drill the holes and file any sharp material down with a file.
Putting the smaller tin inside the bigger one
Step 4: Reverse the 1kg tin so you are putting the smaller tin on top of the large tin's base. Trace a circle into the base of the large tin. Hole punch / drill a hole for your cutters. Using a metal cutter, cut this out carefully from the inside of the drawn circle. The idea is for it to be a tight fit. Put some snips in the perimeter if you can't push the small tin down into it.
Once you have pushed the smaller tin down and it is secure, you can build a pot stand for your pot using another milo tin. The pot stand will let you look in the gasifier as it is boiling water and enable you to add more fuel as needed.
It is a great science project for the kids at home - one that results in a nice mug of hot Milo!