We make biofuel with our own hands: biogas from manure, ethanol for a biofireplace + pellets

Briquettes made from manure, also called dung, burn well, do not harm the environment, and most importantly, you don’t have to pay a lot of money for them: those who have cows, sheep, or at least chickens can make them themselves. For those who do not yet have mains gas, it makes sense to think about using dung.

In this article we will look at:

• What to make fuel briquettes from.
• Technology for manufacturing fuel briquettes.
• How to make a machine for making dung.

Biofuel installations in households

Farms and livestock complexes successfully produce biofuel from manure.
The technology is based on the process of fermentation of manure under the influence of heat in special sealed bunkers, separation of liquid fertilizers, evaporation of excess liquid and drying of the solid product. During fermentation, biogas is released, which is used for heating rooms and cooking, as biofuel for greenhouses or for stoves.

Production of solid fuel from manure

Sufficient volumes of our own raw materials make such a waste-free livestock complex effective. A biofuel boiler house serving all areas of its own farm, heating, gas, electricity obtained from its own raw materials, significantly reduces the total cost of production.

If you have sufficient raw material resources, it is not difficult to produce biofuels with your own hands. Economically, a project for producing biofuel at home makes sense when its quantity is capable of fulfilling any independent energy task.

It is enough to calculate the daily norm of raw materials to obtain the energy consumed daily on the farm for the basic needs listed below:

• biofuel generator to support the production process;
• energy consumption for space heating;
• energy consumption for cooking;
• energy consumption to support agricultural production processes.

Straw is the main raw material for fuel briquettes

The next stage will be the study of the technological process itself, its length in time and the necessary equipment. It is necessary to have or study the basic physics of processes in order to build correctly.

The main technological structures and components are easy to find in photos on the Internet. Manufacturing instructions are often posted by craftsmen on forums, and they themselves willingly share secrets and questions on how to make this or that element most effectively.

Home biofuel installations can produce this resource of different types and conditions, using 100% raw materials and by-products from each stage of its processing.

For example, while producing biofuel for a greenhouse, they simultaneously produce biogas for heating and cooking. Thus, we obtain second-generation biofuel from existing waste.

In a household environment, many biofuel production technologies can be recreated as they were originally taken from nature.

They are based on obtaining energy as a result of natural processes:

• heating naturally or with the slight addition of catalysts;
• drying;
• pressing into briquettes;
• collection of gas from manure fermentation;
• modern process control devices.

The final step in the chain is transportation to the point of consumption, which in most cases is the boiler.

Peat pellets.

This fuel is made from dried peat and is the least quality type of pellet, however, due to its low cost, due to the truly huge reserves of peat in our country, it enjoys a certain popularity. In fact, peat pellets are more often used in industry, but in principle they are also suitable for household fuel boilers, although their ash content is quite high.

Advantages and disadvantages of the system

Biogas plants have many advantages, but there are also a lot of disadvantages, so before starting design and construction you should weigh everything:

• Recycling. Thanks to a biogas plant, you can get the maximum benefit from waste that would otherwise have to be disposed of. This disposal is less hazardous to the environment than landfilling.
• Renewability of raw materials. Biomass is not coal or natural gas, the extraction of which depletes resources. When farming, raw materials appear constantly.
• Relatively small amount of CO2. When gas is produced, 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 capable of critically changing the environment, because... it is absorbed by plants during growth.
• Moderate sulfur release. When biogas is burned, a small amount of sulfur is released into the atmosphere. This is a negative phenomenon, but its scale can be seen in comparison: when burning natural gas, environmental pollution with sulfur oxides is much greater.
• Stable work. Biogas production is more stable than solar panels or wind turbines. While solar and wind energy cannot be controlled, biogas plants depend on human activity.
• Multiple settings can be used. Gas always carries risks. To reduce potential damage in the event of an accident, several biogas plants can be dispersed throughout the site. If a system of several fermenters is properly designed and assembled, it will operate more stable than a single large bioreactor.
• Benefits for agriculture. Some types of plants are planted to obtain biomass. You can choose ones that improve the condition of the soil. For example, sorghum reduces soil erosion and improves its quality.

Biogas also has disadvantages. 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 harvest it in such a way that they deplete the land and upset the ecological balance.

Straw pellets.

Straw is practically a waste material; it is not reused in any way, so pellets made from it have a noticeably lower price than wood pellets. They are common in the southern, agricultural regions of our country, where there is many times more straw than wood waste. Of course, the heat transfer properties of straw are inferior to wood fuel, however, given that straw pellets are much cheaper, and also that there is little wood in the regions, this is the most suitable material of this kind for conditions characterized by a warm climate.

What is biofuel?

Biofuel is an environmentally friendly material produced from bioethanol. It is a colorless and odorless liquid. It is highly flammable. During combustion, it breaks down into water and carbon dioxide, so it is safe for indoor use.

The properties of biofuels are as follows:

1. Ethanol, which is part of the liquid, during combustion breaks down into steam and carbon monoxide and is accompanied by the release of energy. Absolutely harmless to the human body and does not smell.
2. There are no solid decay products (soot, ash) during the operation of the eco-fireplace.
3. Combustion efficiency reaches 95%.
4. Liquids with the addition of sea salt have the crackling effect of natural firewood.
5. When fuel burns, the flames are similar in color and shape to the fire in a classic fireplace.

Ecofuel composition:

The basis of biological fuel is ethanol, of plant origin. It is obtained by fermenting the sugars of most plant crops, such as wheat, beets, potatoes, sugar cane, bananas and others. However, this type of fuel is not sold in its pure form, but is required to denature the alcohol.

For additional effects, dyes or sea salt are added to the liquid.

Ecofuel has the following characteristics:

1. During combustion it does not form ash.
2. Does not emit harmful gases.
3. It is environmentally friendly.
4. Has a long burning period.
5. Easy to use.

Environmentally friendly fuels are produced all over the world. The leading positions in the production of this fuel belong to South Africa, India, and China.

The following types of biofuels are distinguished:

1. Biogas - waste from garbage and production is subjected to pre-treatment and gas is released from it, an analogue of natural gas.
2. Biodiesel is obtained from natural oils and fats of biological origin (animal, microbial, vegetable). The main raw materials for the production of this type of fuel are food industry waste or palm, coconut, rapeseed, and soybean oils. It is most widespread in Europe.
3. Bioethanol is an alcohol-based fuel, a gasoline substitute. Ethanol is produced by fermenting sugars. The raw material for production is cellulosic biomass.

The advantages of environmentally friendly fuel include the following:

1. During the combustion of fuel, smoke, harmful gases, soot and soot are not generated.
2. The intensity of the flame and heat transfer during biofuel combustion can be adjusted.
3. The fuel block and individual structural elements are easy to clean.
4. The design does not require the installation of air exhaust structures.
5. Biofireplace fuel is easy to transport and store.
6. No waste during storage, unlike solid fuel.
7. There is no need to create a separate room for storing large amounts of fuel.
8. Heat transfer during fuel combustion is 95%.
9. During the combustion of ecofuel, the air in the room is humidified due to the release of steam.
10. Flame return is excluded.
11. Thanks to the design of the bio-fireplace and the structural features of the biofuel burner, the design is fireproof.
12. Low fuel cost with low consumption.

Using environmentally friendly fuel is easy in everyday life. Using the gel, you just need to open a jar of gel and install it in the bio-fireplace structure, hiding it in decorative elements or containers. When using liquid fuel, simply pour it into the fuel tank and light it. However, despite all the positive qualities, this substance has several disadvantages.

Disadvantages of biofuels:

1. It is prohibited to store containers with fuel near open fire;
2. Do not add fuel while the biofireplace is operating; you need to extinguish the device and wait for it to cool completely;
3. Lighting the fireplace is permitted only with a special lighter or using electric ignition.

Why does this material burn?

To answer this question, it is necessary to consider the feeding of animals and the processes that occur during the digestion of food.
Any food consists of proteins, carbohydrates, fats, and when fed with grass or hay, fiber (cellulose).

All these substances have one thing in common - their chemical formula contains carbon and hydrogen . In the gastrointestinal tract, chewed food mixed with gastric juice undergoes fermentation, that is, complex substances (biopolymers) break down into simple ones (monopolymers).

In this case, some of the substances are converted into compounds suitable for absorption through the intestinal walls and nutrition of the cells of all tissues of the animal or bird.

Therefore, completely digested food that has turned into feces contains quite a lot of simple organic substances , the basis of which is hydrogen and carbon.

After removing water, the share of which is 50–90 percent, what remains is a mixture of organic and inorganic substances with a fairly high calorific value, and therefore calorific value.

According to this parameter, the excrement of birds or animals in a dried state is at least not inferior to dry (15–20% humidity) firewood , and possibly even superior to them. However, we are talking about the ratio of mass and calorific value, so due to its very low density, dried manure takes up much more space.

Types of biofuels and their features

Biofuel is an environmentally friendly fuel

The presence of the prefix “bio” in the name of a fuel determines its environmental friendliness. After all, renewable natural resources are used in the production of this type of fuel. The main components used in the production of environmental fuel are grains and grasses with a high content of sugar and starch. Thus, cane and corn are the most suitable raw materials for creating biofuels.

Biofuel for biofireplaces, produced from natural components, is not inferior in its energy characteristics to less environmentally friendly analogues:

• bioethanol consisting almost entirely of alcohol, can replace gasoline;
• biogas. being a product of specific processing of various waste waste, like natural gas, it is used to create thermal and mechanical energy;
• Biodiesel is made from vegetable oil for fueling cars and other purposes.

For lighting bio-fireplaces, preference is given to bioethanol, a colorless and odorless liquid.

1. Environmental friendliness is due to the complete absence of carbon monoxide, soot and soot production.
2. Easy to clean burners.
3. Possibility of adjusting combustion intensity.
4. No need to install ventilation devices.
5. High fire safety and reliable use of fuel due to thermal insulation of the fireplace body.
6. Convenient transportation of the fuel itself and ease of installation of fireplaces for its use.
7. It is characterized by 100% heat transfer, since heat is not lost in the wilds of the chimney.
8. There is no need to prepare firewood or clean up side effects near the fireplace: dirt, debris and ash.
9. Water vapor released when ethyl alcohol is heated helps normalize the humidity level in the room.

Conclusion

Dried manure can be a good substitute for firewood or other fuels. This helps not only to save trees and non-renewable energy resources, but also to get rid of accumulated manure heaps, which pose a serious threat and fill the air with an unpleasant odor.

However, the process of turning excrement into finished fuel is very labor-intensive, and using too wet material will not only not provide the required amount of heat, but will also greatly damage the chimney.

Step-by-step instructions for a DIY bio-fireplace

As can be seen from the previous paragraph, if you have step-by-step instructions for a biofireplace, it is very easy to make it yourself. After assembling the burner, the process is divided into the following stages:

The pieces of glass are fastened together with silicone sealant in accordance with the design idea. To dry completely, they need to be left for about 24 hours; a more precise time is indicated in the instructions for the sealant.

If desired, the base of the fireplace can be made from a rectangular metal box. Then it will hide the burner jar.

If the fuel was purchased in a tin can, you just need to place it inside the burner. If it was sold in a plastic container, you should take another tin can and pour it there. The size of the jar should be such that it is convenient to remove from the burner.

Place the pre-prepared wick into the fuel. Place a mesh over the burner and sprinkle pebbles on top of it.

To make a beautiful and simple bio-fireplace with your own hands, the step-by-step instructions above will provide you with all the necessary knowledge. The finished fireplace can be put into operation immediately, that is, the wick can be lit.

Varieties and advantages

Today, there are 3 types of biofuels:

• liquid;
• hard;
• gaseous;

Liquid biofuel

It is the most discussed species. After all, the life of modern man depends on oil; without it, humanity cannot survive, and oil is a fossil resource and at some point its reserves will run out.

Liquid biofuels have the potential to replace this fossil resource.

Liquid biofuels include:

• alcohols (ethanol, methanol, butanol),
• biodiesel,
• biofuel oil,
• esters;

Solid

This mainly includes wood (wood processing waste and fuel pellets, briquettes). The source for obtaining them is usually forests where grass, shrubs and trees grow.

Gaseous fuel

Includes biogas, hydrogen.

Also, biofuels can be classified by generation. There are biofuels of 1st, 2nd, 3rd and 4th generations:

1. The 1st generation includes biofuels obtained by processing agricultural plants into biodiesel and ethanol.
2. 2nd generation – biofuel obtained from food waste.
3. The 3rd generation of biofuels includes biofuels obtained using introduced technologies as a result of the destruction of biomass.
4. The 4th generation of biofuel is produced on lands unsuitable for agriculture and without destruction of biomass.

Another classification of biofuels is the division of biofuels into primary and secondary. Primary biofuel refers to biofuel that has not been processed. To the secondary – processed. Recycled biofuels undergo a variety of modifications before use and can be in solid, liquid and gaseous forms.

Advantages

The advantages of biofuel are as follows:

1. Mobility. Biofuel has the ability to be produced anywhere in the world, regardless of climatic conditions and topography, because this type of fuel can be produced from various organic compounds.
2. Renewability. Since biofuel is obtained from a variety of organic compounds of plant or animal origin, for example, manure, its quantity will not run out.
3. Environmentally friendly. It is a cleaner type of fuel and, when burned, emits fewer harmful substances into the air than fossil fuels.
4. Caring for the environment. Biofuel production solves problems associated with waste disposal.

Which manure is best suited for making fuel?

Since the finished fuel is the same as manure, only in the form of cakes, briquettes or pellets, the most important parameter is its moisture content .
The less water, including urine, this material contains, the more suitable it is for making fuel. In addition, the diet of animals or birds is also of great importance.

After all, meadow grass and hay have lower calorie content than straw or grain, so feeding the latter makes the manure more calorific. In this case, the breed or even the type of animal or bird does not matter much , because after removing excess moisture they will contain approximately the same amount of organic substances.

Biodiesel at home

Biodiesel is a fuel produced from any vegetable oil (sunflower, rapeseed, palm).

Brief description of the biodiesel production process:

1. Vegetable oil is mixed with methanol and a catalyst.
2. The mixture is heated for several hours (up to 50-60 degrees).
3. During the esterification process, the mixture separates into glycerol, which settles down and biodiesel.
4. Glycerin is drained.
5. Diesel is purified (evaporated, settled and filtered).

The finished product of suitable quality is transparent and has a neutral pH.

The yield of biodiesel from vegetable oil is approximately 95%.

The disadvantage of making biological diesel at home is the high cost of vegetable oil. It makes sense to produce biodiesel with your own hands only if you have your own fields for growing rapeseed or sunflower. Or having a constant source of cheap processed vegetable oil.

Biofuel fireplaces are a decorative element of the interior with live fire. The industrial production of biofireplaces offers models of a wide variety of sizes and configurations. However, many people make biofireplaces with their own hands.

To make a fuel block for a biofireplace with your own hands, you need to take a metal box and place a container with bioethanol inside. Cover the box with a metal grill (you can use a simple barbecue grill). Place the wick on the grate, light it, and the bio-fireplace is ready.

Essentially, that’s all you need to make a biofireplace with your own hands. All that remains is to decorate it with stones or other elements to your taste.

There is very little heat from such a fireplace; it is rather just an original decoration for the house.

It is quite possible to make fuel for a biofireplace with your own hands. It contains ethanol and gasoline. Let's consider the process of producing bioethanol at home.

The following ingredients will be required:

Ethyl alcohol 96%, sold in pharmacies Aviation gasoline (it is also used to refill lighters)

It is practically odorless, which is important for use in a residential area. You only need about 70 g per liter of alcohol

gasoline. Mix well and pour into the fuel container. A liter of biofuel will last from 2 to 8 hours of continuous burning, depending on the type of fireplace burner and flame intensity

For a liter of alcohol you only need about 70 g of gasoline. Mix well and pour into the fuel container. A liter of biofuel will last from 2 to 8 hours of continuous burning, depending on the type of fireplace burner and flame intensity.

DIY biofuel

Bioethanol is a safe type of fuel; when burned, only hydrogen gas and carbon dioxide are released. However, an open fire burns oxygen, so you need to regularly ventilate the room. This will also help remove excess carbon dioxide from the air.

Bioreactor

There are quite strict requirements for manure processing tanks:

It must be impermeable to water and gases. Water resistance should work in both directions: the liquid from the bioreactor should not pollute the soil, and groundwater should not change the state of the fermented mass. The bioreactor must have high strength. It must withstand the mass of the semi-liquid substrate, the gas pressure inside the container, and the soil pressure acting outside

In general, when constructing a bioreactor, special attention must be paid to its strength.

Ease of maintenance. More convenient to use cylindrical containers - horizontal or vertical

In them, mixing can be organized throughout the entire volume; stagnant zones do not form in them. Rectangular containers are easier to implement when building with your own hands, but cracks often form in their corners, and the substrate stagnates there. Stirring it in the corners is very problematic.

All these requirements for the construction of a biogas plant must be met, as they ensure safety and create normal conditions for processing manure into biogas.

What materials can it be made from?

Resistance to aggressive environments is the main requirement for materials from which containers can be made. The substrate in the bioreactor can be acidic or alkaline. Accordingly, the material from which the container is made must tolerate various environments well.

Not many materials meet these requests. The first thing that comes to mind is metal. It is durable and can be used to make containers of any shape. The good thing is that you can use a ready-made container - some old tank. In this case, the construction of a biogas plant will take very little time. The disadvantage of metal is that it reacts with chemically active substances and begins to collapse. To neutralize this disadvantage, the metal is coated with a protective coating.

An excellent option is a bioreactor container made of polymer. Plastic is chemically neutral, does not rot, does not rust. You just need to choose from materials that can withstand freezing and heating to fairly high temperatures. The reactor walls should be thick, preferably glass fiber reinforced. Such containers are not cheap, but they last a long time.

It is possible to build a bioreactor for the production of biogas from brick, but it must be well plastered using additives that ensure water and gas impermeability

A cheaper option is a biogas plant with a container made of bricks, concrete blocks, or stone. In order for the masonry to withstand high loads, it is necessary to reinforce the masonry (in every 3-5 rows, depending on the thickness of the wall and the material). After completing the wall construction process, to ensure water and gas impermeability, subsequent multi-layer treatment of the walls is necessary both inside and outside. The walls are plastered with a cement-sand composition with additives (additives) that provide the required properties.

Reactor sizing

The reactor volume depends on the selected temperature for processing manure into biogas. Most often, mesophilic is chosen - it is easier to maintain and it allows for the possibility of daily reloading of the reactor. Biogas production after reaching normal mode (about 2 days) is stable, without surges or dips (when normal conditions are created). In this case, it makes sense to calculate the volume of the biogas plant depending on the amount of manure generated on the farm per day. Everything is easily calculated based on average statistical data.

The decomposition of manure at mesophilic temperatures takes from 10 to 20 days. Accordingly, the volume is calculated by multiplying by 10 or 20. When calculating, it is necessary to take into account the amount of water that is necessary to bring the substrate to an ideal state - its humidity should be 85-90%. The found volume is increased by 50%, since the maximum load should not exceed 2/3 of the tank volume - gas should accumulate under the ceiling.

For example, there are 5 cows, 10 pigs and 40 chickens on a farm. The result is 5 * 55 kg + 10 * 4.5 kg + 40 * 0.17 kg = 275 kg + 45 kg + 6.8 kg = 326.8 kg. To bring chicken manure to 85% humidity, you need to add a little more than 5 liters of water (that’s another 5 kg). The total weight is 331.8 kg. For processing in 20 days you need: 331.8 kg * 20 = 6636 kg - about 7 cubic meters only for the substrate. We multiply the found figure by 1.5 (increase by 50%), we get 10.5 cubic meters. This will be the calculated value of the reactor volume of the biogas plant.

Specifics of biogas production

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

Its properties are practically no different from natural gas, which is used for industrial and domestic needs.

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

They are placed in a bioreactor, where processing occurs:

• the biomass is exposed to bacteria for some time. The fermentation period depends on the volume of raw materials;
• As a result of the activity of anaerobic bacteria, a flammable mixture of gases is released, which includes methane (60%), carbon dioxide (35%) and some other gases (5%). Fermentation also releases potentially dangerous hydrogen sulfide in small quantities. It is poisonous, so it is highly undesirable for people to be exposed to it;
• the mixture of gases from the bioreactor is purified and supplied to a gas tank, where it is stored until it is used for its intended purpose;
• gas from a gas tank can be used in the same way as natural gas. It goes to household appliances - gas stoves, heating boilers, etc.;
• Decomposed biomass must be regularly removed from the fermenter. This is additional labor, but the effort pays off. After fermentation, the raw material turns into high-quality fertilizer, which is used in fields and vegetable 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. You can get 70-80 cubic meters of substrate. biogas, but gas production is uneven and depends on many factors, including biomass temperatures. This complicates calculations.

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

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

Homemade biogas equipment, assembled from scrap materials, is much cheaper than industrial production plants. Its efficiency is lower, but it is well worth the investment. If you have access to manure and the desire to put in your own effort to assemble and maintain the structure, this is very profitable.

Review of popular brands

Biodiesel for automobiles is mainly produced in America (USA, Canada and Brazil), as well as India, China and Europe. This is often presented as concern for the environment and increased use of alternative energy sources.

The output result is quite ambiguous. It’s one thing when waste is processed to make such fuel, and quite another thing is the processing of plants specially grown for this purpose.

The main ingredient of all brands of biofuel for fireplaces is alcohol; it does not have any particular differences in quality and composition between different manufacturers (+)

The situation with ethanol biofuel is somewhat different. It is produced on a much smaller scale. This is mainly done in Europe, but Russia also has its own factories. To produce this biofuel, raw materials of plant origin are also needed, but not in such huge volumes as in the case of the automobile analogue.

In domestic stores, you can choose fireplace biofuel from the following brands:

1. Kratki BioDECO (Poland).
2. InterFlame (Russia).
3. BioKer (Russia).
4. Planika Fanola (Germany).
5. Vegeflame (France).
6. Bionlov (Switzerland).
7. Bioteplo Slimfire (Italy).

The choice is quite extensive. The price per liter ranges from 260–600 rubles. Cost often depends on the presence/absence and combination of additional additives. Some aromatic oils are quite expensive. Although they are present in biofuels in very small proportions, they still affect the price.

How to choose

When choosing fuel for biofireplaces, you need to pay attention to a number of factors:

• availability of certificates of conformity;
• indicator of productivity and energy capacity;
• absence of decomposition products in the fuel tank after combustion;
• absence of sharp and unpleasant odors from the liquid;
• best before date;
• authenticity of packaging;

Sunflower husk pellets.

Sunflower is also a very common agricultural crop in the southern treeless regions of the country. The heat transfer of pellets from the husk of this plant (husk) is very high, literally at the level of white wood pellets. However, they have a fairly high ash content due to the increased oiliness of the material, so a boiler fired with sunflower husk pellets must be cleaned very often. However, the very low cost of this fuel makes it quite popular. The same can be said about fuel pellets made from the husks of other agricultural plants, for example, buckwheat or corn husks. Buckwheat and corn pellets have the highest thermal output of all pellets made from vegetable husks.

Instructions for self-construction

If you have no experience in assembling complex systems, it makes sense to select online or develop the simplest drawing of a biogas plant for a private home.

The simpler the design, the more reliable and durable it is. Later, when you develop skills in building and handling the system, you can redo the equipment or install an additional installation.

Expensive industrial designs include systems for biomass mixing, automatic heating, gas purification, etc. Household equipment is not that complicated. It is better to assemble a simple installation, and then add elements that are needed

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

This is an average figure, because The caloric content of biogas is usually not higher than 6000 kcal/m3.

In order for the fermentation process to proceed more or less stably, it is necessary to achieve the correct temperature conditions. To do this, the bioreactor is installed in an earthen pit or reliable thermal insulation is thought out in advance. Constant heating of the substrate can be ensured by placing a water heating pipe under the base of the fermenter

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

Stage 1 – preparing the pit for the bioreactor

Almost the entire biogas plant is underground, so a lot 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 optimal solution is to purchase ready-made polymer rings with a solid bottom. They will cost more than available materials, but no additional sealing will be required. Polymers are sensitive to mechanical loads, but are not afraid of moisture and chemically aggressive substances. They cannot be repaired, but if necessary they can be easily replaced.

The intensity of fermentation of the substrate and the release of gas depend on the preparation of the walls and bottom of the bioreactor, so the pit is carefully strengthened, insulated and sealed. This is the most difficult and time-consuming stage of work

Stage 2 – arrangement of gas drainage

Purchasing and installing special mixers for biogas plants is an expensive proposition. The system can be made cheaper by installing gas drainage. It consists of vertically installed polymer sewer pipes with many holes made in them.

When calculating the length of drainage pipes, you should focus on the planned filling depth of the bioreactor. The tops of the pipes must be above this level.

For gas drainage, you can choose metal or polymer pipes. The former are stronger, and the latter are more resistant to chemical influences. It is better to give preference to polymers, because metal will quickly rust and rot

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 a normal supply of biomethane through the outlet pipe.

Stage 3 – installation of the dome and pipes

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

The bioreactor container is closed with a tight lid. To prevent biomethane from mixing with air, a water seal is installed. It also serves for gas purification. A release valve must be provided that will operate if the pressure in the fermenter is too high.

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

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

How to achieve maximum biogenerator efficiency

To achieve maximum efficiency of the biogenerator, the fermentation of the organic mixture must be uniform. The substrate must constantly move in order to get maximum gas.

Thanks to submersible or inclined mixers, which are equipped with an electric drive, constant mixing of the biomass is ensured. These stirrers are located at the top or side of a typical reactor.

In homemade installations, a mechanical mixing device similar to a household mixer is used. It can be manual or powered.

The most important condition for effective biogas production is compliance with the temperature regime. Heating can be carried out:

• using automated heating systems. They are used in stationary installations. If the temperature in the reactor drops below the set point, the system automatically turns on. When the desired temperature is reached, the system turns off automatically;
• using gas boilers - direct heating is carried out using electric heating devices or built-in heating elements.

A layer of glass wool can be an excellent frame for a reactor. Expanded polystyrene is also suitable for thermal insulation. These materials will help reduce heat loss.

Methods for heating a bioreactor

Microorganisms that process the substrate are constantly present in the biomass, but for their intensive reproduction they need a temperature of 38 degrees or higher.

For heating during cold periods, you can use a coil connected to the home heating system or electric heaters. The first method is more economical, so it is used more often.

The biogas plant does not have to be buried in the ground; there are other options for arrangement. An example of the operation of a system assembled from barrels is shown in the video below.

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