Biogas plant for a private house: recommendations for arranging homemade

Amir Gumarov
Checked by a specialist: Amir Gumarov
Author: Irina Yakushchenko
Last update: April 2019

A smart owner dreams of cheap energy, efficient waste management and fertilizer. Do-it-yourself home biogas plant is an inexpensive way to make your dreams come true.

Self-assembly of such equipment will cost a reasonable price, and the gas produced will be a good help in the household: it can be used for cooking, heating the house and other needs.

Let's try to understand the specifics of this equipment, its advantages and disadvantages. And also whether it is possible to independently build a biogas plant and whether it will be effective.

The specifics of biogas production

Biogas is formed as a result of fermentation of a biological substrate. It is decomposed by hydrolysis, acid and methane-forming bacteria. A mixture of gases produced by bacteria is combustible, because contains a large percentage of methane.

In its properties, it practically does not differ from natural gas, which is used for industrial and domestic needs.

Industrial biogas plant
If desired, each home owner can purchase a biogas plant for industrial production, but it is expensive, and the investment pays off within 7-10 years. Therefore, it makes sense to make efforts and make a bioreactor with your own hands

Biogas is an environmentally friendly fuel, and the technology for its production does not have a special impact on the environment. Moreover, waste materials that need to be disposed of are used as raw materials for biogas.

They are placed in a bioreactor, where processing takes place:

  • biomass has been exposed to bacteria for some time. Fermentation time depends on the volume of raw materials;
  • as a result of the activity of anaerobic bacteria, a combustible mixture of gases is released, which includes methane (60%), carbon dioxide (35%) and some other gases (5%). Also, during fermentation in small quantities, potentially hazardous hydrogen sulfide is released.It is poisonous, so it is highly undesirable for people to be exposed to it;
  • the mixture of gases from the bioreactor is cleaned and enters the gas tank, where it is stored until intended use;
  • gas from a gas tank can be used in the same way as natural gas. He goes to household appliances - gas stoves, heating boilers, etc .;
  • decayed biomass must be regularly removed from the fermenter. This is an additional work, but the effort pays off. After fermentation, the raw materials turn into high-quality fertilizer, which is used in fields and gardens.

A biogas plant is beneficial for the owner of a private house only if he has constant access to waste from livestock farms. On average from 1 cubic meter. substrate can be obtained 70-80 cubic meters. biogas, but gas production is uneven and depends on many factors, including biomass temperature. This complicates the calculations.

Scheme of the device of the production plant
Biogas plants are ideal for farmers. Animal waste can provide enough gas for proper heating of residential premises and farm buildings

In order for the gas production process to be stable and continuous, it is best to build several biogas plants, and lay the substrate in the fermenters with a time difference. Such plants operate in parallel, and the raw materials are loaded in them sequentially.

This ensures a constant gas production, so that it can be continuously supplied to household appliances.

Effective Home Installation Diagram
Ideally, the bioreactor should be heated. Every 10 degrees of heat doubles the gas production. Although the arrangement of heating requires investment, it pays off with greater efficiency of the design

Homemade biogas equipment, assembled from improvised materials, is much cheaper than industrial production plants. Its effectiveness is lower, but it is consistent with the invested funds. If you have access to manure and a desire to make your own efforts for the assembly and maintenance of the structure, this is very beneficial.

Advantages and disadvantages of the system

Biogas plants have many advantages, but there are enough shortcomings, so before starting the design and construction, everything should be weighed:

  • Recycling. Thanks to the biogas plant, you can get the maximum benefit from the garbage, which would still have to be disposed of. This disposal is less hazardous to the environment than landfill.
  • Renewability of raw materials. Biomass is neither coal nor natural gas, the extraction of which depletes reserves of resources. When farming, raw materials appear constantly.
  • Relatively small amount of CO2. When receiving gas, the environment is not polluted, but when it is used, a small amount of carbon dioxide is released into the atmosphere. It is not dangerous and is not able to critically change the environment, because plants absorb it during growth.
  • Moderate sulfur release. When biogas is burned, a small amount of sulfur enters the atmosphere. This is a negative phenomenon, but its scale is known by comparison: when burning natural gas, environmental pollution with sulfur oxides is much greater.
  • Stable work. Biogas production is more stable than work solar panels or windmills. If the energy of the sun and wind cannot be controlled, then biogas plants depend on human activity.
  • You can use several settings. Gas is always a risk. To reduce potential damage in the event of an accident, several biogas plants can be dispersed throughout the site. If you correctly design and assemble a system of several fermenters, it will work more stable than one large bioreactor.
  • Benefits for agriculture. To obtain biomass, certain types of plants are planted. You can choose those that improve the condition of the soil.For example, sorghum reduces soil erosion, improves its quality.

Biogas has its drawbacks. Although it is a relatively clean fuel, it still pollutes the atmosphere. There may also be problems with the supply of plant biomass.

Irresponsible plant owners often procure it in such a way that they drain the land and upset the ecological balance.

Calculation of the profitability of the installation

Cow dung is usually used as raw material for biogas production. One adult cow can give him enough to provide 1.5 cubic meters. fuel; pig - 0.2 cubic meters; chicken or crawl (depending on body weight) - 0.01-0.02 cbm. To understand whether it is a lot or a little, one can compare it with more familiar types of resources.

1 cbm biogas provides the same amount of thermal energy as:

  • firewood - 3.5 kg;
  • coal - 1-2 kg;
  • electricity - 9-10 kW / h.

If you know the approximate weight of agricultural waste that will be available in the coming years, and the amount of energy needed, you can calculate the profitability of a biogas plant.

Easy compost heap installation
One of the main disadvantages of biogas production is the smell. The possibility of using small compost heaps is a big plus, but you will have to endure the inconvenience and carefully control the process so as not to provoke the spread of pathogens

For laying in the bioreactor, a substrate is prepared, which includes several components in the following proportions:

  • manure (best cow or pork) - 1.5 t;
  • organic waste (it can be decayed leaves or other components of plant origin) - 3.5 t;
  • heated to 35 degrees water (the amount of warm water is calculated so that its mass is 65-75% of the total amount of organic matter).

Calculation of the substrate is made for one bookmark for six months, based on moderate gas consumption. After about 10-15 days, the fermentation process will give the first results: gas will appear in small quantities and begin to fill the storage. After 30 days, you can expect full fuel production.

Indian version of a simple biogas plant
Equipment for the production of biogas is not yet particularly common in our country. This is largely due to the poor awareness of people about the benefits and features of biogas systems. In China and India, many small farms are equipped with handicrafts to provide additional clean fuel.

If the installation works correctly, the biogas volume will gradually increase until the substrate decays.The design productivity directly depends on the biomass fermentation rate, which in turn is related to the temperature and humidity of the substrate.

Self-building instruction

If there is no experience in assembling complex systems, it makes sense to select the network or develop the simplest drawing of a biogas plant for a private house.

The simpler the design, the more reliable and durable it is. Later, when there are skills in building and handling the system, it will be possible to remake equipment or mount an additional installation.

Simplified Home Installation Drawing
In expensive designs of industrial production, biomass mixing systems, automatic heating, gas purification, etc. are provided. Home appliances are not so complicated. It’s better to put together a simple installation, and then add elements that you need

When calculating the volume of the fermenter, it is worth focusing on 5 cubic meters. This installation allows you to get the amount of gas needed to heat a private house with an area of ​​50 square meters, if a gas boiler or stove is used as the heat source.

This is an average indicator, as the calorific value of biogas is usually not higher than 6000 kcal / m3.

Deepening bioreactors into the ground
In order for the fermentation process to proceed more or less stably, it is necessary to achieve the correct temperature regime. To do this, the bioreactor is installed in an earthen pit or pre-thought out reliable thermal insulation. Constant heating of the substrate can be ensured if a water heating pipe is placed under the base of the fermenter

The construction of a biogas plant can be divided into several stages.

Stage 1 - preparation of the pit for the bioreactor

Almost the entire biogas plant is underground, so much depends on how the pit was dug and finished. There are several options for strengthening the walls and sealing the pit - plastic, concrete, polymer rings.

The best solution is to buy ready-made polymer rings with a blank bottom. They will cost more than improvised materials, but additional sealing will not be required. Polymers are sensitive to mechanical stress, but are not afraid of moisture and chemically aggressive substances. They cannot be repaired, but if necessary they will be easily replaced.

Pit for biogas plant
The intensity of substrate fermentation and gas outlet depend on the preparation of the walls and bottom of the bioreactor; therefore, the pit is carefully strengthened, insulated and sealed. This is the most difficult and time-consuming stage of work.

Stage 2 - gas drainage

Buying and installing special mixers for biogas plants is an expensive pleasure. The system can be cheapened by arranging gas drainage. It is a vertically mounted polymer sewer pipesin which many holes have been made.

When calculating the length of the drainage pipes, one should be guided by the planned depth of filling of the bioreactor. The upper parts of the pipes must be above this level.

Sewer Polymer Pipes
For gas drainage, you can choose metal or polymer pipes. The former are stronger and the latter more resistant to chemical influences. It is better to give preference to polymers, as metal quickly rusts and rots

You can immediately load the substrate into the finished bioreactor. It is covered with a film so that the gas released during the fermentation process is under slight pressure. When the dome is ready, this will ensure the normal flow of biomethane through the outlet pipe.

Stage 3 - installation of the dome and pipes

The final stage of assembly of the simplest biogas plant is the installation of the domed top. At the highest point of the dome, a gas exhaust pipe is installed and pulled to gas holder, which is indispensable.

The capacity of the bioreactor is closed with a tight lid. To prevent the mixing of biomethane with air, equip a water trap. It also serves to purify gas. It is necessary to provide a release valve that will operate if the pressure in the fermenter is too high.

Read more on how to make biogas from manure. in this material.

Homemade biogas plant on site
The free space of the bioreactor to some extent serves as a gas storage, but this is not enough for the safe operation of the installation. Gas must be consumed constantly, otherwise explosion from excessive pressure under the dome is possible

Methods for heating a bioreactor

Microorganisms processing the substrate are constantly present in biomass, however, for their intensive reproduction, a temperature of 38 degrees and above is needed.

For heating in the cold season, you can use a coil connected to the heating system at home, or electric heaters. The first method is economically more profitable, therefore it is most often used.

It is not necessary to dig a biogas plant into the ground; there are other options for arranging it. An example of a system assembled from barrels is shown in the video below.

Substrate heating in a bioreactor
The easiest way is to arrange heating from below, laying a pipe from the heating system, but the efficiency of such a heat exchanger is relatively low. It is better to equip external heating, ideally steam, so that the biomass does not overheat

Conclusions and useful video on the topic

Although there is nothing complicated in assembling and equipping biogas equipment, you need to be extremely attentive to details. Errors are not allowed, because may cause explosions and destruction. We offer video instructions that will help you understand the device setup, assemble them correctly and supplement with useful devices for more convenient use of biogas.

The video tells how the standard biogas plant is arranged and works:

An example of a homemade biogas plant. DIY video tutorial on arranging the system:

Video instruction for assembling a biogas plant from a barrel:

Description of the process of manufacturing mixers for the substrate:

A detailed description of the work of a makeshift gas storage:

No matter how simple the biogas plant chosen for a private house is, you should not save on it. If possible, it is better to buy a collapsible bioreactor for industrial production.

If not, make from high-quality and durable materials: polymers, concrete or stainless steel. This will create a truly reliable and safe gas supply system at home.

Have questions about the topic of the article, find any flaws or is there any valuable information that you can share with our readers? Please leave your comments, ask questions, share experiences.

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Visitors Comments
  1. Alyona

    I correctly understood that it is best to install a biogas plant on a livestock farm? There are plenty of raw materials, and space for the installation of the device itself. Dad once worked on a sheep farm as a shepherd. There were night shifts, and it was cold in the room where people spent the night. I don’t even know if the sheepfolds were heated. And so the idea is quite feasible, with the right hands and the head can be implemented.

  2. Vadim

    Still, it’s good that humanity is slowly coming to the idea of ​​maintaining a clean environmental situation, awakening responsibility, consciousness and the desire to search for alternative sources. After all, our children live here. I liked the idea of ​​a biogas plant.It seems to be nothing complicated at first glance, it will be very profitable if we take into account our gas prices. But there are, of course, disadvantages that should not be overlooked.

  3. Question 1 (probably the most important) - is there a land plot (cottage) with an area of ​​about 0.5 Hectare. I want to build such an installation (hands grow where necessary). How comfortable will it be for a person in the immediate vicinity of such an installation - in other words, will there not be a stink “on a hectare”? I understand that a lot of things depend on the design and build quality, but suppose everything is done as it should.

    Question 2: And how, in fact, to clean such a plant from processed raw materials? And again, a sub-question: do you need a gas mask closed or can you get by with the open type?

    And last question 3: Are special bacteria required for biomass fermentation, or is it just a commercial move?

    PS: As for gas prices, DA-A_a - (for a long time printing mats in relation to yourself you know to whom and where ...) - I have a one-room apartment insulated by all the rules, but for gas heating we get an equal (or even more) bill than for all other utilities - electricity, water, utilities for “Utrimuvannya Budinka and Pribudinkovo ​​Territors” and the Internet - TOGETHER Taken !!!
    Draw conclusions, Ladies and Gentlemen!

    • Erlan

      It will be much more comfortable for a person in the immediate vicinity of such an installation than in the immediate vicinity of a stinking heap of dermis and debris in an open space.

      In any case, shit emits gases (methane and others), and if you need biohumus, then you need to wait 2-3 years so that the shit rots and all harmful gases disappear. But biogas plants are a solution to a global problem. Well, if you make a system, then there will be no stink. Even the sound of some units operating in this system will not be heard. Only it is necessary to think over well.

      As a result, fair disposal of waste, free bio-energy, free fertilizers. I think that every farmer is simply obliged to install such a reactor just to dispose of the waste.

      I came across this topic for one reason, because began to think about organizing a mini chicken farm. Everything was clearly planned and rested on shit - she will stink, the neighbors will complain. I studied sanitary standards - you can’t build a chicken farm in the village. “Here is the barrier”, I thought, and somehow it came from no reason to use the waste ... but the question is - how? I thought a lot and heard from somewhere about a biogas plant. Total If you are engaged in KH, then you must engage in a biogas plant. If you don’t have KH then it’s not profitable to deal with biogas.

  4. I will answer Alena and Vadim.

    All this crap is realizable! But no one answered my questions. After all, the thing is that Oil / Gazprom is absolutely not profitable / unprofitable ALTERNATIVE SOURCES OF ENERGY! And our fucking lousy government will do everything possible to kill attempts to give birth to such technologies in the bud. About the financial support of such enterprises - I am silent in a rag.

    Well, in general, a biogas plant is possible even at the suburban area of ​​0.25 ha. But it all depends on the specific requirements / capabilities. I heard (I do not claim) that at one of the dachas in Poltava region the excess biogas was stupidly burned so that it didn’t stink, because the compressors could not cope with filling a battery of serially connected biogas storage cylinders.

  5. Vladimir

    If there is no manure, but there are empty corn stalks and ears or wheat (rye) straw, tops, leaves, etc., then how much such raw materials will be needed to produce one cubic meter of gas?

    • Expert
      Amir Gumarov

      Hello. I will try to answer regarding each raw material for which you have questions.The numbers will not be accurate, with some error, since they depend on many factors that cannot be calculated “by eye”.

      So, a ton of straw according to preliminary data will make it possible to obtain about 300 cubic meters of gas. Regarding the leaves, here is not so simple, since there is no specific mention on your part which trees are in question. But even now, experimental (amateur) installations allow you to get 50 cubic meters of gas from one ton of leaves.

      I think that this information will be enough to calculate the approximate productivity of the future installation. You can also consider getting biogas from organic waste. For reference, I also attach a plate with data on other types of raw materials.

      Attached photos:
  6. Dmitry

    I read all the comments and I will answer immediately for everyone. In one of the examples above, just my experimental setup. According to the operating experience - the installation is tight, therefore there is no smell, if there is a smell, then there is a logical lack of tightness, which means there is a loss of gas. After processing, the raw material has a small, odor, but it does not look like manure, slop or analogues, it has a slight bitter smell. Working off from the reactor is a quality biohumus, which after aeration can be safely cast into beds. Aeration with air is needed to kill all methanogens.

    The reactor is best done in a continuous cycle, as do the reactor - flooded, wait two weeks, a week produces gas and then everything merges, I think it’s not practical. It is most optimal to add 5-7% of fresh raw materials every 1-2 days and drain as much, then the reactor will produce gas continuously.

    The volume of gas per day is on average equal to one and a half reactor volumes. Just do not confuse liquid and gaseous gas. The bioreactor gives exactly gaseous.

    If you have your own home, then a bioreactor with a volume of at least 5 cubic meters is needed for heating. And yes, the bioreactor must be insulated and part of the gas spent on heating it in the winter.

  7. Alexander

    In principle, everything is clear to me, except for how to remove everything that has decayed. If you make 2 reactors of 3 cubic meters, what are the proportions of the contents in one reactor? Is it possible to add substrate during reactor operation? Thank you in advance for your reply.