How to Build a Biogas Plant at Home?

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Today, I would like to start by making you all imagine a scenario. Just imagine a world, where you don’t have to pay your electricity bills, LPG bills and you don’t even have to pay a single penny for the fuel. Well, this dream can be a reality. In fact, this dream had come true a long ago but, many of us simply don’t know about it. The simple answer to fulfill this dream is BIOGAS Plant.

I have talked about biogas in my previous posts also, emphasizing on the importance of it. Today, I’ll tell you all, how to build one at home so you can satisfy your energy needs. 

I had recently built a new biogas plant at my farm to suffice my farming needs. Now, let us see how the biogas plant came together step by step.

Building the base of the biogas plant:

 

The first step you need to take is of building the base of the whole biogas plant. For this, first, dig a hole in the ground. It should be around 3 feet deep and should have a radius of 2 meters.

At the bottom of the hole, lay a thick base of sand (around 6 inches). The next step is laying the iron bars. Make a concentric ring structure of the iron bars something like this.

Biogas plant base

Now, we have to construct the base of the biogas plant using concrete. This process is very similar to the construction of cement roads.

Just as the construction workers lay down a thick layer of concrete for constructing cement roads, we have to lay down a thick layer of concrete to make a circular base of the biogas plant. It is should be about 10 inches thick.

Biogas digester concrete base

Constructing the digester of the Biogas Plant:

 

The base we have laid down will act as the bottom of the digester.

We all know the digester looks somewhat like a tank and this is the place where the organic material we feed is decomposed, giving us biogas.

As the digester is nothing but a tank, we need to build a dome-like structure on the base that we have constructed. The dome will be open from the top.

This process is rather easy. The guys who constructed our biogas plant had a dome-shaped structure which was calibrated according to the size of the biogas plant.

The dome-shaped structure was formed using many iron plates. These iron plates were connected to each other using nut bolts and forming a dome after tightening all the plates together. The dome was open from the top.

Dome-shaped ready-made structure

Now, the workers just put on some concrete outside the dome structure. On the sidewalls, they also placed supporting plates from outside after constructing a thick layer of the concrete wall.

Construction of the Biogas digester

After the concrete dried and the wall became firm, they disassembled the dome-shaped structure. And ta-da, a digester was ready which looked something like this.

One important thing, two holes have also been made on the dome on opposite sides. One for the inlet of the feed and one for the outlet of the sludge or the decomposed material.

Biogas digester

Constructing the tank to support the dome and store excess material:

 

Just above the digester, we have to construct another tank. This tank is cylindrical and has the same radius as of the digester. This tank is used to hold the plastic dome (that will collect the biogas) in one place. Also, excess decomposed material is stored here.

This plastic dome is surely easy to install as it is very light in weight. This lightweight of the dome can also be disadvantageous for us if the level of the biogas increases substantially.

As the dome is light in weight, the biogas will push the dome up and up, increasing the chances of losing the biogas from the bottom of the dome if the dome gets full with biogas.

To hold it in one place, four iron support beams are introduced from the wall of this tank. The top of the digester and these iron beams hold the dome in one place.

Tank above the digester

Remember we had completely closed the digester from the top. Instead, we had kept it partially open. This is done to channelize all the biogas inside the dome only.

Tank above the digester

If this is not done and the tank was kept as it is, we will lose some of the biogas from the sides of the plastic dome. This partial dome structure helps us to avoid wastage of the biogas by channelizing all the biogas inside the dome.

Tank above the digester

Constructing the slurry tank (feed tank):

 

As we know, we have to feed the biogas digester. For that, we have to make a separate tank for feeding the slurry in.

This is a very small tank where the organic material is mixed with water so as to make a slurry of it. This slurry is then fed to the biogas digester using a pipe connected between the slurry tank and the digester.

Slurry tank

I personally put cow dung only, in the digester. The cow dung needs to be properly mixed with water reducing its consistency and making a slurry of it.

This tank is placed higher than the digester so that the slurry can easily slide down in the digester because of gravity. Also, the pipe coming from the slurry tank comes all the way to the bottom and the pipe that is connected to the sludge is placed higher than the pipe of the slurry tank.

Slurry tank for Biogas

This is done to introduce the fresh feed at the bottom so as to decompose it. Next time, when fresh feed is introduced in the digester the old feed moves up and as the pipe connected to the sludge tank is placed higher, it only takes out the feed which is old and has been decomposed.

Collecting the sludge:

 

I personally had not created a tank for collecting sludge. I have dug a big hole in the ground which collects the sludge. Sludge is the decomposed material which comes out of the digester after the new slurry is fed in.

To know more about the working of the biogas plant in detail, please read this post of mine- Working of Biogas Plant.

Sludge Tank for Biogas

The slurry is something that we feed in, to the digester, daily and in small quantity. Hence, the small tank works well for feeding the slurry. However, sludge is something that is collected daily.

We empty the sludge tank only after the tank is full, that is, after a few months. That is exactly why we do not build a concrete tank for collecting sludge.

One more advantage of not building a concrete tank sludge tank is that the hole that we have dug decomposes the sludge further, leaving us with excellent organic fertilizer.

The Dome For Collecting Biogas:

 

The world now has progressed a lot. we now have found a lot of ready to use and simple solutions for many difficult problems.

Earlier installing a dome for a biogas plant was a big hassle as it was made up of iron and weighed a lot. So, installing such a huge tank was anything but easy.

Plastic dome for collecting Biogas

Today, we have found a great solution for this. With an increase in the demand for biogas plants, industries have now started manufacturing plastic domes, ready to be installed directly above the digester.

We can install the dome directly above the digester after feeding the digester with slurry.

Initially, we have to put a lot of slurry, so as to have enough slurry in the digester to make the dome float but, nowadays, this problem has been solved by plastic domes.

Interconnecting Pipes:

 

Remember, we have made holes on the digester and the tank above it. As I have told you earlier, these holes are for connecting the slurry tank and the sludge tank to the digester.

This is done using pipes. There are two pipes, one between the slurry tank and the digester and the second between the digester and the sludge tank.

Covering the biogas Plant:

 

After construction of the biogas plant, it is important to cover the biogas plant. Covering the biogas plant is adviced to avoid entry of unwanted matter from the top. It also acts as a safety measure, any person or animal should be able to enter it.

Tiles to cover the Biogas Plant

Hence, it is essential to cover the plant. To do so, we made four concrete tiles, which when placed side to side, they form a circle. These four tiles are shown in the picture and they are placed on the top of the plant to cover it.

One last thing:

 

Everything is done now. The only thing left is connecting the pipe to the dome for carrying the biogas to our stoves.

This is also a simple process nowadays. the plastic domes that we install, already have an outlet at the top which has proper arrangements for connecting the pipe.

We only have to connect a pipe to this outlet and carry the biogas wherever we desire.

Pipe acting as the outlet of the Biogas dome

There are two main precautions that we have to take here:

  1. The pipe we have connected should be firmly connected ensuring there are no leakages so that, we do not lose any of the biogas.
  2. It should be fixed firmly with the tank avoiding any probabilities of leakages in the future.

Conclusion:

 

Finally, the Biogas Plant is ready. My biogas plant is fully functional now and working great. Here is how it looks now.

Biogas Plant

With this in mind, I think we are ready to build a biogas plant of our own. I would also recommend you to read this article first just to get an overview of this topic.

As always, I would keep on pushing you to get your own biogas plant. A biogas plant with few additions to it can solve your energy problems for life.

Now, lets come back to our dream. Remember at the start of this article I asked you some questions. Now, you would be wondering, how is it possible that a simple biogas plant can save us from our electricity bills, LPG bills and at the same time, save us from our high fuel expenses.

Well, I have explained this in my earlier posts. To know how to save electricity bills, LPG bills and fuel expenses please read this post of mine. Also, to know how to get hot water from a biogas plant, free, please read this post.

 

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