Drill a hole in the side of your plastic jug large enough for the straw to slide through. Insert the straw 2 inches deep, then duct tape around it to ensure the jug stays airtight and the straw doesn't fall in or out.
Attach the plastic bag to the other end of the straw. Tape the mouth of the bag closed around the straw--again, so no air can get in.
Choose your waste material. Manure, especially chicken manure, produces the most methane, but compost will also work.
Mix your waste material with a handful of straw or newspaper strips. Add in a third as much water as you have waste material; for example, if you have three pints of waste material, add one pint of water. Stir until the waste material, water, and straw or newspaper are thoroughly mixed. The result is called slurry.
Pour and seal the slurry in your plastic jug. Stir the slurry gently each day to speed decomposition and to keep a hard crust--which will trap oxygen and interrupt methane production--from forming. To stir, pin the straw closed with your clothespin at the jug end so no slurry will escape into the bag. Swirl the jug around lightly for a few seconds. When you finish, put the jug down and unpin the straw. Make sure the straw is open again and not bent shut.
Wait. In two weeks (at about 50 degrees Celsius) to two months (at 15 degrees Celsius) bacteria will have eaten all the oxygen inside the jug, and methane will form and be caught in the bag.
Things You Will Need
- Plastic jug
- Drill with small bit
- Drinking straw
- Heavy-duty plastic bag
- Duct tape
- Waste material, such as compost or manure
- One page of newspaper torn into strips or a handful of hay/straw
- Small pin, such as a clothespin or a hairpin
- Warmth is necessary for methane production. Either do your experiment in spring or summer or have a heat source ready.
- This is a small, experimental version of a methane generator. A version large enough to generate enough energy to power a house, for example, would require daily manure collection from roughly 150 cows, the welding experience to connect the metal drum holding slurry to the methane collector and the know-how to use methane as a fuel. Perform this miniature version first to see how methane production works, how long methane takes to develop with the materials you've chosen and to make sure you're doing everything correctly.