Growing your own gas is an innovation perfected by people in underdeveloped countries. We look at how they generate biogas and how you can do it too.
For South-East Asian and African countries, blackouts, floods, and going without gas and power is just another part of daily life. To compensate, their normal creations are considered innovations for those of us in more developed countries seeking a way to create green energy and live that off-the-grid lifestyle. I have traveled through a number of South East Asian countries and one household item that stood out to me was the DIY biogas digestor.
Making a biogas plant is incredibly easy. I have done it with a very small container as a test and it worked quite well even though my device only used a balloon as a way to hold a small portion of gas without pressure to the balloon. After traveling and seeing these in action I found this video of some inventive kids that had made a much larger one from a school project.
It is cheap to make, easy to keep, and its only output is a material that is a high-nutrient fertiliser. That’s a game changer. So let’s look at how it works, and how you can make your own in 7 easy steps.
What is biogas?
Biogas is a byproduct gas caused by the breakdown of scraps and waste in a contained space without oxygen. In a biogas generator the process that causes the gas is called anaerobic digestion. If that makes you think of your stomach then it should, because that is exactly what it is, a breakdown of material in an area without oxygen, just like what your stomach does to your food.
The types of material, or fuel in this case, that you can use to make biogas are endless because it really is a stomach that handles anything organic. The most important ingredient to use in a biogas generator is manure. This produces the highest level of methane and is why there is a very compelling argument to use biogas on farms with cattle as it puts a renewable energy use to cow manure.
Other materials you can throw into your biogas generator can be anything that is an organic material. For instance, you could use grass, leftover meat, old kitchen scraps, noodles, bread, whatever you have it can go in there.
7 Steps To Make Your Own Biogas
You are going to need some materials to start with. Some of these you might already have around the house, some you might have to pick up from a store or online.
- The container: I would go with one of those 20-litre office water cooler bottles if you can get one. This is the smallest I would recommend as my small balloon experiment was pointless other than being a test. In South East Asia there seems to be a very abundant supply of water poly drums. I would say get one of those if you want to run a big supply of gas, otherwise a moderate container would just be a simple water cooler 5-gallon bottle.
- PVC hosing to connect from the biogas digestor to the gas holder and valve
- PVC piping
- Gas tap valve
- T-valve (it should have three connectable points)
- Funnel (for the scraps and manure)
- Gas holder: most of the biogas digesters I have seen use a tyre tube (something you would use in the water when you go swimming). This can be unsafe depending on where you store it as eventually it is going to be full of gas so will become a highly flammable item. You should be considerate of where you place it as this is a safety issue.
- Super glue or an airtight sealant
- Saw to cut PVC pipe
- Black paint for the water container to stop sunlight
You need to measure the PVC pipe against the height of the container. Mark it off and saw it off at the same height as pictured above. This will be the inlet pipe.
If you are using the 5-gallon water cooler bottle you can also put your ingredients in through the top and then keep the cap on the top of it. At the start when you put your manure and water in this it would be the best place to do that.
You will also need to measure out an outlet pipe which would be running horizontally through the container. Measure the PVC pipe at half of the width of the container. This way you can use it as the outlet from the middle-point of the container.
Mark the outline of the PVC piping onto the top of the container and on the side of the container. For the inlet pipe, you want to have it located on the top, in between the middle and the outside of the container. For the outlet, it should be about 10cm from the top width of the bottle. You can use the picture below as a reference. 
Once you have made the markings, cut them out. There are various ways to do this depending on the material you are working with. The video that I have used as a demonstration from these kids used a soldering iron, however, a drill would also do the trick.
When you feed the inlet pipe in (from the top) make sure you leave 2-3 inches of space at the bottom. This is so inlet waste can drain through the pipe and if there is any blockages you have space to push the contents down through the inlet pipe.
You will also need to do the same process for the gas feed, this would be done in a position similar to the one below. Once that’s done, feed the piping through.
After you have fed pipes through we need to airproof our container. So we should be using a sealant like a rubber glue or as used in this example, super glue with sand.
Make sure your pipes are covered on the exposed ends with caps. We only want to open them when we are feeding waste into the inlet pipe, or pouring our fertiliser out of the outlet pipe.
Don’t forget to seal your gas feed hose.
Remember that T-Valve that we had in the equipment list? Use that on the end of your gas hose. You also need another two pieces of PVC hosing. One of them will connect to the tyre or wherever you choose to store your gas reserve, while the other will be attached to the valve.
The valve is the end that you will use to cook, or to burn off if you are using this merely for the nutrients in the fertiliser. For some people, having this near the kitchen window means that they can feed their gas piping through the window and into a camp stove or side burner so that when they want to cook, the gas is there ready to go.
Attach the middle part of the T-valve to your hose that connects to your tube. You should have an air nipple on your tube that you can use to feed the gas in. Just leave this on and will be full in a week depending upon the materials you use in the biogas digest.
One hack is to also sit a plank of wood on the tube and eventually set a stone on top of that. The extra weight keeps the pressure of the gas in the tube so that when you are ready to cook with your gas you can release the valve slowly for a good feed of gas.
The last step, use your fuel. I didn’t just put this picture of cow poo in here for nothing, it’s the best type of fuel for our biogas digester. If you don’t have cows around you can use any other sort of manure. Even chicken poo is good enough to get the bacteria working in our digester.
Another good idea is to paint your water container black. This stops sunlight shining into the container which would otherwise cause oxygen-producing algae. We don’t want that. We want a dark non-oxygen environment like our stomach to get all of the good stuff happening.
When you are using your fuel I would suggest using 1kg of manure with 1 litre of water. Let it sit for two days before you add any other things like food scraps or anything else.
As a small project, you can give this a go with hardly any cost whatsoever and then increase the size once you get more confident with the process. You can increase the size to however you see fit. As you can see in the video below, villages in Africa are using much larger systems that run on the same principles as this one to provide gas and gas power to an entire village. And don’t forget that juicy outlet, that works amazing on the crops.
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Great stuff
Thank you for sharing.