DIY bio gas installation. Alternative heating - biogas plant. Where is biogas used

A DIY biogas plant can be done without much effort. Its use will significantly save on energy resources, which are becoming more and more expensive each time today. If you decide on your own to build equipment that allows you to get biogas from waste, you can consume cheap energy, which will be used to heat your home and other needs.

Beneficial use

If during the operation of the installation surplus of biogas or fertilizers will be formed, that is, the opportunity to sell them at market prices, thereby you will turn into profit what literally lies under your feet. If you are a large farmer, then you have the opportunity to purchase a ready-made biogas plant. These plants, manufactured at the factory, are very expensive, but have a long life span.

A DIY biogas plant can be made from scrap materials, it will not be very expensive, and such equipment will work according to the same principle. In this case, you can use the available tools, as well as the details available in the wizard's arsenal.

Biogas generation principle

If you set out to make a plant that will operate on biological gas, then you need to present the technology of biogas generation. So, in a special container, which is called a bioreactor, the process of processing biological mass is carried out, anaerobic bacteria take part in this.

A DIY biogas plant for a home on quail droppings works on the principle of creating conditions that are characterized by the absence of air and fermentation. All this lasts for some time, the duration of which depends on the amount of raw materials used in the process.

Ultimately, a mixture of gases is formed, which contains 60% methane and 35% carbon dioxide. The rest of the gaseous components are contained in the mass in an amount of 5%. Among the latter, hydrogen sulfide can be distinguished in an insignificant amount. The gas formed in this way is continuously removed from the reactor, and after the cleaning process passes, it is sent to the intended use.

Service features

Waste that has undergone processing becomes high-quality fertilizers, which must be removed from the bioreactor from time to time. They can be laid on the fields. A DIY biogas plant can be done effortlessly if you have access to livestock and agricultural businesses. This indicates that biogas production will be economically viable only if there is a source of supply of manure and other organic waste from livestock production.

Features of self-construction of a bioreactor

In order to understand how to independently make a biogas plant, you need to figure out what parts it consists of. You can take as a basis the simplest equipment diagram that you can build on your own. The design does not provide for heating and a mixing device, however, there is one of the main parts - a reactor, which is also known as a digester. This component is required for the processing of manure. In addition, there is a bunker through which raw materials are loaded. It is necessary to provide the structure with an entrance hatch, as well as a water seal. But in order to be able to unload waste raw materials, a pipe will be needed. Such an element will be required in order to realize the possibility of biogas removal.

This is how a biogas plant diagram looks like. It is not difficult to make such a structure with your own hands. In order to receive free biofuel, on the site, you should choose a place where you can build a reinforced tank, which will be based on concrete. This vessel will act as a bioreactor. At its base, it is necessary to provide for the presence of a hole through which raw materials that have been worked out will be removed. This hole must be made so that it is possible to close it well. This is due to the fact that the functioning of the system is possible only in sealed conditions.

The dimensions of the concrete compartment can be determined taking into account the amount of organic waste used at a time. You need to find out how much raw materials will appear every day on a farm or private backyard. But it is not worth saving, since it will be possible to ensure the full operation of the bioreactor only if the tank is filled by 2/3 of the available volume. If you manufacture a biogas plant with your own hands from a barrel, then it will work according to the following principle: as soon as organic waste gets into the well-closed container of the bioreactor, which is located at a depth in the soil, they begin to ferment, which leads to the release of biogas.

Features of the manufacture of containers

A DIY biogas plant can be made taking into account the daily use of a small amount of waste. In this case, it is permissible to replace the reinforced concrete tank with a steel container, which can even be a barrel. If you decide to resort to just such a solution, then it is necessary to choose a metal vessel, guided by some rules.

First of all, you need to pay attention to the welded seams, which must be sufficiently strong and tight. When using a small container, you should not expect to be able to obtain a significant amount of biogas. The yield will depend on the mass of organic waste that is processed at a time in the reactor. Thus, in order to generate 100 m 3 of biogas, it is necessary to process a ton of waste.

Reactor heating equipment

A do-it-yourself biogas plant for home can be made in such a way that during its operation it will be possible to obtain greater efficiency. This is provided by heating. Such manipulations will speed up the process of fermentation of biological mass. If the equipment is installed in the southern regions, then this need does not arise. The ambient temperature provides natural activation of fermentation. However, if the unit operates in regions with a cold climate, then in the winter period heating acts as a prerequisite for the operation of biogas production equipment. It must be remembered that the fermentation process begins at a temperature that exceeds 38 o C.

Methods for equipping a biogas plant with heating

A DIY biogas plant for home can be equipped with heating in several ways. The first assumes the need to connect the unit to the heating system as a coil. It needs to be mounted under the reactor. The second method involves installing an electric heating element in the base of the tank. The third method is characterized by the provision of direct heating of the tank by using electric heating systems, gas equipment. The activation of biogas production at home can be supplemented with the function of mixing the mass in the compartment. To do this, design a device that resembles a household mixer. It will be driven by a shaft brought out through a hole in the lid; alternatively, it can be positioned in the walls of the tank.

Equipment of the installation with an output system

A mini-biogas plant, designed with your own hands, cannot work without a gas removal system. For this, the unit must have a special hole, which must be mounted in the upper part of the lid, the latter must close the tank well. To exclude the possibility of gas mixing with air, it is necessary to ensure that it is removed through a water seal.

You can get a cheap energy source yourself, at home - you just need to assemble a biogas plant. If you understand the principle of its functioning and the device, then it is not difficult to do this. The mixture it produces contains a large amount of methane (depending on the feedstock, up to 70%), so it has a wide range of applications.

Refueling gas cylinders of cars as fuel for heating boilers is not a complete list of all possible options for using the finished product. How to assemble a biogas plant with your own hands is our story.

There are several designs of the unit. When choosing one or another engineering solution, you need to understand how the given installation suits local conditions. This is the main criterion for assessing the feasibility of installation. Plus to this - its own capabilities, that is, what type of raw materials and in what volume can be used, what can be done with your own hands.

Biogas is obtained from the decomposition of organic matter, but its "yield" (in volume terms), and, therefore, the efficiency of the installation depends on what exactly is loaded into it. The table contains the relevant information (approximate data), which will help to determine the choice of a specific engineering solution. Some explanatory graphs will also be useful.

Design options

With manual loading of raw materials, without heating and stirring

For domestic use, this model is considered the most convenient. With a reactor capacity of 1 to 10 m³, manure of about 50 - 220 kg will be needed daily. It is from this that we need to proceed, determining the size of the container.

The installation is installed in the ground, so a small foundation pit is required for it. In accordance with its calculated dimensions, a place is selected on the site. The composition and purpose of all elements of the circuit is easy to understand.

Installation feature

After installing the reactor in place, it is necessary to check its tightness. Then the metal is to be painted (preferably with a frost-resistant composition) and insulated.

• The waste is removed naturally - either in the process of filling a new portion, or with an excess of gas in the reactor with the valve closed. Therefore, the capacity of the waste collection container must be no less than that of the working one.
• Despite the simplicity of the device and the attractiveness for assembling with your own hands, due to the fact that mixing of the mass and heating is not provided, it is advisable to operate this installation option in regions with a mild climate, that is, mainly in the south of Russia. Although with high-quality thermal insulation, in conditions when underground water layers are deep, this design is quite suitable for the middle zone.

Unheated but stirring

Almost the same thing, only a slight modification, which significantly increases the productivity of the installation.

How to make a mechanism? For those who assembled with their own hands, for example, this is not a problem. A shaft with blades will have to be mounted in the reactor. Therefore, it is necessary to install support bearings. It is good to use a chain as a transmission link between the shaft and the lever.

The biogas plant can be operated in almost all regions, with the exception of the northern regions. But unlike the previous model, it needs supervision.

Stirring + heating

Thermal action on biomass increases the intensity of the decomposition and fermentation processes taking place in it. The biogas unit is more versatile in use, as it can operate in two modes - mesophilic and thermophilic, that is, in the temperature range (approximately) 25 - 65 ºС (see graphs above).

In this diagram, the boiler runs on the resulting gas, although this is not the only option. Biomass heating can be carried out in different ways, as it is more convenient to organize it for the owner.

Automated options

The difference between this scheme is that it is connected to the installation. This allows you to accumulate gas reserves, and not immediately consume it for its intended purpose. Ease of use also lies in the fact that almost any temperature regime is suitable for intensive fermentation.

This installation is even more efficient. It is capable of processing up to 1.3 tons of raw materials per day with a similar reactor volume. Loading, mixing - pneumatics is "responsible" for this. The discharge channel allows waste to be removed either to a hopper for short-term storage, or to mobile containers for immediate removal. For example, to fertilize fields.

For domestic use, these options for a biogas plant are hardly suitable. Their installation, and even with their own hands, is much more difficult. But for a small farm - a good solution.

Mechanized biogas plant

The difference from previous models is in an additional tank, in which the preliminary preparation of the raw mass takes place.

Compressed biogas is fed into the feed hopper and then into the reactor. It is also used for heating.

The only thing that is needed when assembling any of the installations with your own hands is accurate engineering calculations. You may need to consult a specialist. The rest is pretty simple. If at least one of the readers is interested in the biogas unit and assembles it on their own, then the author was not in vain working on this article. Good luck!

Required mandatory materials:

• two containers;
• connecting pipes;
• valves;
• gas filter;
• means for ensuring tightness (glue, resin, sealant, etc.);

Desirable:

• stirrer with an electric motor;
• temperature sensor;
• pressure sensor;

The sequence below is suitable for southern regions. For operability in any conditions, a reactor heating system should be added, which will provide heating of the vessel to 40 degrees Celsius and increase thermal insulation, for example, enclose the structure with a greenhouse. It is desirable to cover the greenhouse with a black film. It is also advisable to add a condensate outlet to the pipeline.

Building a simple biogas plant:

1. Create storage tank. We select a tank where the resulting biogas will be stored. The reservoir is fixed with a valve and equipped with a pressure gauge. If gas consumption is constant, then there is no need for a gas tank.
2. Insulate the structure inside the pit.
3. Install pipes. Lay pipes into the pit for loading raw materials and unloading compost humus. An inlet and outlet are made in the reactor vessel. The reactor is placed in a pit. Pipes are fed to the holes. The pipes are secured tightly with glue or other suitable means. Pipes less than 30 cm in diameter will tend to clog. The loading location should be on the sunny side.
4. Install the sunroof. The rector, equipped with a hatch, makes repair and maintenance work more convenient. The hatch and the reactor vessel should be glued with rubber. You can also install sensors for temperature, pressure and level of raw materials.
5. Select a container for the bioreactor. The selected container must be strong - since a large amount of energy is released during fermentation; have good thermal insulation; be airtight and waterproof. Ovoid vessels are best suited. If it is problematic to build such a reactor, then a cylindrical vessel with rounded edges would be a good alternative. Square-shaped containers are less efficient because hardened biomass will accumulate in the corners, making fermentation difficult.
6. Prepare the pit.
7. Choose a place for the installation of the future installation. It is advisable to choose a place far enough from the house and so that you can dig a hole. Placement inside the pit can significantly save on thermal insulation, using cheap materials like clay for this.
8. Check the tightness of the resulting structure.
9. Start the system.
10. Add raw materials. We are waiting about two weeks for all the necessary processes to pass. The necessary condition for gas combustion is to get rid of carbon dioxide. For this, a regular filter from a hardware store is suitable. A homemade filter is made from a piece of gas pipe 30 cm long, filled with dry wood and metal shavings.

Composition and types

Biogas is a gas obtained as a result of a three-phase biochemical process over biomass, which takes place in a sealed environment.

The process of decomposition of biomass is sequential: first it is exposed to hydrolysis bacteria, then acid-forming and finally methane-forming. The material for microorganisms at each stage is the product of the activity of the previous stage.

At the output, the approximate composition of biogas looks like this:

• methane (50 to 70%);
• carbon dioxide (from 30 to 40%);
• hydrogen sulfide (~ 2%);
• hydrogen (~ 1%);
• ammonia (~ 1%);

The accuracy of the proportions is influenced by the raw materials used and the gas production technology. Methane has a combustion potential; the higher its percentage, the better.

Ancient cultures dating back more than three thousand years (India, Persia or Assyria) have experience in using combustible bog gas. The scientific basis was formed much later. The chemical formula of methane CH 4 was discovered by the scientist John Dalton, the incorporation of methane into the bog gas was discovered by Humphrey Davy. The Second World War played an important role in the development of the alternative energy industry, requiring from the belligerents an enormous need for energy resources.

The possession of the USSR with huge reserves of oil and natural gas led to the lack of demand for other technologies for energy production, the study of biogas was mainly the subject of interest of academic science. At the moment, the situation has changed so much that, in addition to the industrial production of various types of fuel, any person can create a biogas plant for their own purposes.

Installation device

- a set of equipment for biogas production from organic raw materials.

By the type of raw material supply, the following types of biogas plants are distinguished:

• portioned;
• continuous feed;

Biogas plants with a constant feed are more efficient.

By the type of raw material processing:

1. Without automatic stirring raw materials and maintaining the required temperature - complexes with a minimum configuration, suitable for small farms (Scheme 1).
2. With automatic stirring, but without maintaining the required temperature - also serves small farms, more efficient than the previous type.
3. With the support of the required temperaturebut without automatic mixing.
4. With automatic mixing of raw materials and temperature control.

Principle of operation

The process of converting organic raw materials into biogas is called fermentation. The raw material is loaded into a special container that provides reliable protection of biomass from oxygen access. An event that occurs without oxygen interference is called anaerobic.

Under the influence of special bacteria, fermentation begins in an anaerobic environment. As fermentation develops, the raw material becomes covered with a crust, which must be regularly destroyed. Destruction is done by thorough mixing.

Mixing the contents is required at least twice a day, without violating the tightness of the process. In addition to removing the crust, stirring allows you to evenly distribute acidity and temperature inside the organic mass. As a result of these manipulations, biogas is produced.

The resulting gas is collected in a gasholder, from there it is delivered to the consumer through pipes. Biofertilizers obtained after processing raw materials can be used as a food additive for animals or added to the soil. This fertilizer is called compost humus.

The biogas plant includes the following elements:

• capacity for homogenization;
• reactor;
• stirrers;
• storage tank (gas-holder);
• heating and water mixing complex;
• gas complex;
• complex of pumps;
• separator;
• control sensors;
• Instrumentation with visualization;
• safety system;

An example of an industrial biogas plant is shown in diagram 2.

Raw materials used

Decomposition of any animal or plant residues produces flammable gas to varying degrees. Mixtures of different composition are well suited for raw materials: manure, straw, grass, various waste, etc. The chemical reaction requires 70% humidity, so the raw material must be diluted with water.

The presence of cleaning agents, chlorine, washing powders in organic biomass is unacceptable, since they prevent chemical reactions and can damage the reactor. Also, raw materials with conifer sawdust (containing resins), with a high proportion of lignin and with an excess of the humidity threshold of 94% are not suitable for the reactor.

Vegetable. Vegetable raw materials are excellent for biogas production. The maximum yield of fuel is provided by fresh grass - about 250 m 3 of gas with a methane share of 70% is obtained from a ton of raw materials. Corn silage is slightly smaller - 220 m 3. Beet tops - 180 m 3.

Almost any plant, hay or algae can be used as biomass. The disadvantage of this application is the length of the production cycle. The biogas production process takes up to two months. The raw material must be finely chopped.

Animal. Waste from processing, dairy, slaughterhouses, etc. suitable for biogas plant. The maximum output of fuel is provided by animal fats - 1500 m3 of biogas with a methane content of 87%. The main disadvantage is scarcity. Animal raw materials must also be crushed.

Excrement. The main advantage of manure is its cheapness and easy availability. Disadvantage - the quantity and quality of biogas is lower than from other types of raw materials. Horse and cow excrement can be recycled immediately. The production cycle will take approximately two weeks and will yield a yield of 60 m 3 with 60% methane content.

Chicken manure and pig manure cannot be used directly because they are toxic. To start the fermentation process, they must be mixed with silage. Human waste products can also be used, but sewage will not work as the faecal content is low.

Schemes of work

Scheme 1 - biogas plant without automatic mixing of raw materials:

Scheme 2 - industrial biogas plant:

Finally, we give a list of useful information that will help you avoid additional problems when creating a biogas plant:

1. Practice says that to heat a dwelling with an area of \u200b\u200b50 m 2, it is necessary to consume 3.5 m 3 of gas per hour.
2. It is undesirable to use biogas directly for cooking, because taste may change.
3. Avoid getting solid objects (nuts, bolts, etc.) into the raw material, because the equipment may deteriorate.

For biogas to burn stably, it must meet certain standards:

• methane content at least 65% (optimum content from 90 to 95%);
• there must be no water vapor, hydrogen and carbon dioxide;
• normal gas supply pressure 12.5 bar;

In the event that, during a pressure surge or for other reasons, the gas goes out, and its supply continues, it can lead to tragic consequences. Therefore, modern equipment with gas control sensors should be used.

The theoretical foundations of methane gas production from biomass by anaerobic digestion were presented.

The role of bacteria in the step-by-step transformation of organic matter was explained, with a description of the necessary conditions for the most intensive biogas production. This article will provide practical implementations of biogas plants, with a description of some homemade structures.

As energy prices rise, and many owners of livestock farms and small farms have problems with waste disposal, industrial complexes for the production of biogas and small biogas plants for a private house have appeared on sale. Using search engines, the Internet user can easily find an affordable ready-made solution so that the biogas plant and its price meet the needs, get in touch with equipment suppliers and agree on the construction of a biogas generator at home or on the farm.

Industrial complex for the production of biogas

Bioreactor - the basis of a biogas plant

The capacity in which the anaerobic decomposition of biomass occurs is called bioreactor, fermenter, or metantan. Bioreactors are completely sealed, with a fixed or floating dome, and have a diving bell design. Bell psychrophilic (not requiring heating) bioreactors look like an open reservoir with liquid biomass, into which a container in the form of a cylinder or a bell is immersed, where biogas is collected.

The collected biogas puts pressure on the cylinder, which causes it to rise above the tank. Thus, the bell also functions as a gas holder - a temporary storage of the generated gas.

Floating dome bioreactor

The disadvantage of the bell design of the biogas reactor is the impossibility of mixing the substrate and its heating during cold periods of the year. Also a negative factor is a strong odor, and unsanitary conditions due to the open surface of a part of the substrate.

In addition, part of the generated gas will escape into the atmosphere, polluting the environment. Therefore, these bioreactors are used only in artisanal biogas plants in poor countries with hot climates.

Another example of a floating dome bioreactor

In order to prevent environmental pollution and eliminate unpleasant odors, the reactors of biogas plants for home and large industries have a fixed dome design. The shape of the structure in the process of gas formation does not matter much, but when using a cylinder with a dome-shaped roof, significant savings in building materials are achieved. Fixed dome bioreactors are equipped with nozzles for adding new portions of biomass and collecting spent substrate.

Fixed Dome Bioreactor

Main types of biogas plants

Since the fixed dome design is the most acceptable, most bioreactor solutions are of this type. Depending on the loading method, bioreactors have a different design and are subdivided into:

• Batch, with a one-time loading of the entire biomass, and with subsequent complete unloading after the processing of raw materials. The main disadvantage of this type of bioreactor is the uneven gas evolution during the processing of the substrate;
• continuous loading and unloading of raw materials, due to which a uniform release of biogas is achieved. Due to the design of the bioreactor, during loading and unloading, biogas production does not stop and there are no leaks, since the pipes through which the biomass is added and removed are made in the form of a hydraulic seal preventing gas outflow.

Sample batch bioreactor

Batch biogas reactors can be of any design to prevent gas leakage. For example, at one time in Australia, channel metantanks with an elastic inflation vault were popular, where a small excess pressure inside the bioreactor inflated a bubble made of durable polypropylene. When a certain pressure level inside the bioreactor was reached, the compressor was turned on, pumping out the produced biogas.

Duct bioreactors with elastic gasholder

The type of fermentation in this biogas plant can be mesophilic (with low heating). Due to the large area of \u200b\u200bthe inflating dome, duct bioreactors can only be installed in heated rooms, or in regions with hot climates. The advantage of the design is that there is no need for an intermediate receiver, but a big disadvantage is the vulnerability of the elastic dome to mechanical damage.

Large channel bioreactor with elastic gas tank

Recently, batch bioreactors with dry fermentation of manure without adding water to the substrate are gaining popularity. Since the manure has its own moisture, it will be enough for the life of organisms, although the intensity of the reactions will decrease.

Dry bioreactors have the appearance of a sealed garage with tightly closing doors. The biomass is loaded into the reactor using a front-end loader and remains in this state until the end of the full gassing cycle (approximately six months), without the need to add the substrate and stir it.

Batch bioreactor with loading through a hermetically closing door

DIY biogas plant

It should be noted that in most bioreactors, as a rule, only the gas generation zone is hermetically sealed, and the liquid biomass at the inlet and outlet is under atmospheric pressure. Overpressure inside the bioreactor displaces part of the liquid substrate into the nozzles, due to which the level of biomass in them is slightly higher than inside the tank.

The red lines in the diagram indicate the difference in levels in the bioreactor and the nozzles

These designs of home-made bioreactors are popular among folk craftsmen who independently make biogas plants with their own hands for the house, allowing reusable manual loading and unloading of the substrate. When making bioreactors with their own hands, many craftsmen experiment with completely sealed containers, using several rubber chambers from the tires of wheels of large vehicles as a gas holder.

Drawing of a gas tank made from tractor chambers

In the video below, an enthusiast of home-made biogas production, using the example of barrels filled with poultry droppings, proves the possibility of actually obtaining combustible gas at home, processing waste from the poultry house into useful fertilizer. The only thing that can be added to the design described in this video is that you need to put a pressure gauge and a safety valve on a homemade bioreactor.

Bioreactor productivity calculations

The amount of biogas is determined by the weight and quality of the raw materials used. On the Internet, you can find tables where the amount of waste produced by various animals is indicated, but the owners who have to remove manure every day do not need this theory, since, thanks to their own practice, they know the amount and mass of the future substrate. Based on the availability of stocks of raw materials renewable every day, it is possible to calculate the required volume of the bioreactor and the daily biogas production.

Table of obtaining the amount of manure from some animals with an approximate calculation of the biogas yield

After the calculations and the approved design of the bioreactor, you can proceed to its construction. The material can be a reinforced concrete container, poured into the ground, or brickwork, sealed with a special coating, which is used to process the pools.

It is also possible to build the main tank of a home biogas plant made of iron, covered with anti-corrosion material. Small industrial bioreactors are often made from large volume chemically resistant plastic tanks.

Construction of a brickwork bioreactor

In industrial biogas plants, electronic control systems and various reagents are used to correct the chemical composition of the substrate and its acidity level, and special substances are added to the biomass - enzymes and vitamins that stimulate the multiplication and vital activity of microorganisms inside the bioreactor. As microbiology advances, more and more resistant and effective strains of methanogen bacteria are being created, which can be purchased from biogas companies.

It can be seen from the graph that with the use of enzymes, the maximum biogas yield occurs twice as fast

The need for pumping out and purifying biogas

Constant gas production in a bioreactor of any design leads to the need to pump out biogas. Some primitive biogas plants can burn the produced gas directly in a burner installed nearby, but the instability of the overpressure in the bioreactor can lead to the disappearance of the flame and subsequent release poisonous gas... The use of such a primitive biogas plant connected to a stove is categorically unacceptable due to the possibility of poisoning raw biogas with toxic components.

Burner flame during biogas combustion must be clean, even and stable

Therefore, almost any scheme of a biogas plant includes gas storage tanks and a gas purification system. As a homemade cleaning complex, you can use a water filter and a homemade container filled with metal shavings, or purchase professional filtration systems. The tank for temporary storage of biogas can be made of chambers from tires, from which gas is pumped from time to time by a compressor into standard propane cylinders for storage and subsequent use.

In some African countries, inflatable gas tanks in the form of a pillow are used for storing and transporting biogas.

An improved bioreactor with a floating dome can be perceived as an alternative to the mandatory use of a gasholder. The improvement consists in the addition of a concentric baffle, which forms a water pocket that acts like a water seal and does not allow the biomass to come into contact with air. The pressure inside the floating dome will depend on its weight. Passing gas through the purification system and the reducer, it can be used in a household stove, periodically bleeding from the bioreactor.

Floating dome bioreactor with water pocket

Grinding and mixing of the substrate in the bioreactor

Stirring the biomass is an important part of the biogas generation process, providing bacteria with access to nutrients that can become lumpy at the bottom of the bioreactor. In order for the biomass particles to be better mixed in the bioreactor, they must be crushed mechanically or manually before loading into the metantank. Currently, industrial and home-made biogas plants use three methods of mixing the substrate:

1. mechanical stirrers, driven by an electric motor or manually;
2. circulating mixing by means of a pump or a propeller pumping the substrate inside the bioreactor;
3. bubbling mixing by blowing liquid biomass with existing biogas. The disadvantage of this method is the formation of foam on the surface of the substrate.

The arrow indicates a mixing circulating screw in a homemade bioreactor

Mechanical mixing of the substrate inside the bioreactor can be carried out manually, or automatically, by turning on the electric motor using an electronic timer. Water-jet or bubbling mixing of biomass can only be carried out using electric motors, manually controlled or using a software algorithm.

This bioreactor is equipped with a mechanical stirring device

Substrate heating in mesophilic and thermophilic biogas plants

The optimum temperature for gassing is the substrate temperature in the range of 35-50ºC. To maintain this temperature in the bioreactor, various heating systems - water, steam, electric. Temperature control should be carried out using a thermostat or thermocouples connected to an actuator that regulates the bioreactor heating.

It should also be remembered that an open flame will overheat the walls of the bioreactor, and the biomass will burn inside it. A burnt substrate will reduce the heat transfer and the quality of heating, and the hot wall of the bioreactor will quickly collapse. One of the best options is water heating from the return pipe of the home heating system. It is necessary to install a system of electric valves to be able to turn off the heating of the bioreactor or connect the heating of the substrate directly from the boiler if it is too cold.

Electric and water heating system for bioreactor

Heating the substrate in a bioreactor using heating elements will be beneficial only if there is an alternative electricity obtained from a wind generator or solar panels. In this case, heating elements can be connected directly to a generator or battery, which will exclude expensive voltage converters from the circuit. To reduce heat loss and reduce the cost of heating the substrate in the bioreactor, it is necessary to insulate it as much as possible with the help of various insulation materials.

Thermal insulation of the bioreactor with thermal insulation material

Practical experiments inevitable when building biogas plants with your own hands

No matter how much literature a novice biogas enthusiast reads, and no matter how many videos he watches, in practice you will have to learn a lot yourself, and the results, as a rule, will be far from the calculated ones.

Therefore, many novice craftsmen follow the path of independent experiments in obtaining biogas, starting with small containers, determining how much gas from the available raw materials is produced by its small experimental biogas plant. Component prices, methane yields and the future costs of building a fully functional biogas plant will determine its profitability and feasibility.

In the video above, the master demonstrates the capabilities of his biogas plant, noting how much biogas will be produced in one day. In his case, when pumping eight atmospheres into the receiver of the compressor, the volume of the resulting gas after recalculations, taking into account the volume of the container 24 liters, will be about 0.2 m².

This volume of biogas obtained from a two-hundred-liter barrel is not significant, but, as shown in the next video of this master, this amount of gas is enough for an hour of burning one stove burner (15 minutes multiplied by four cylinder atmospheres, which is twice the receiver).

In another video below, the master talks about the production of biogas and organic fertilizers by processing organic waste in a biogas plant. It should be borne in mind that the value of ecological fertilizers can exceed the cost of the produced gas, and then biogas becomes a useful by-product of the process of making quality fertilizers. Another useful property of organic raw materials is the ability to store it for a certain period for use at the right time.

In Serbia, and in Europe as a whole, people do not want to depend on energy and gas companies, so they seek to acquire alternative energy sources. Be it solar panels, thermal collectors, or biogas plants.

I once already told in my magazine about biogas plants for industrial production, now my story is about a homemade plant that can produce gas for your home or summer cottage. The principle of operation is clear from the figure. I will just explain and tell you the purpose of some of the elements.

To manufacture the installation you will need:

* Two plastic barrels of 200 liters each (in Serbia, cabbage is salted in such barrels), but there can also be metal barrels from diesel fuel.

* Five adapters-fittings for connecting elements with a hose with a thickness of at least 13 mm.

* Plastic hose (length according to the needs of the installation).

* Plastic bucket.

* Plastic canister 3 - 5 liters (from car oil with screw cap) for the emergency valve.

* Two plastic tubes with a diameter of 5 cm.

Element 1 - in the figure, BIO gas generator

It consists of: a sealed shaft, two plastic pipes and a biogas outlet.

In the generator, organic matter decays during the decay process, releasing 60% methane and 40% SO2.

Through the first plastic tube with a funnel, finely cut biomass waste is poured, mixed with water in a ratio of 10% biomass and 90% rainwater (soft water).

It would be good if we could also add a natural mixture of fresh manure from cows, pigs and poultry in order to introduce microorganisms on which biogas production depends. If not, you can add some mud from a river or pond to speed up the process.

The process takes about 3 weeks for the gas to form. Early on, you will notice that gas is being released, but know that this is SO2 - carbon dioxide, which is not flammable. Only after 3 weeks have passed does the formation of methane - biogas.

Residue appears at the bottom of the container over time, which is an excellent natural fertilizer for vegetables in horticulture.

The ideal temperature is 12 to 36 degrees, protect the barrel from direct sunlight in the shade, and in winter from freezing. Keep in mind that this is a "living" barrel, meaning that it contains billions of microorganisms working to decompose the biomass.

If you "overcook" or "freeze" the BIO Gasifier, microorganisms will disappear, so the whole process will have to start over.

Element 2 in the figure is a container for collecting biogas and a water seal

It consists of an open plastic barrel, a bucket and two fittings (valve)for gas flow and weight (tags).

In this container - a 200 liter barrel, gas is collected, as shown in the figure. Provides a simple and flexible solution without wasting gas. In addition, water also acts as a filter, purifying methane from impurities.

Note that the gas has lifted the container of water, which indicates the amount of gas collected.

The weight of the weight will help to make the gas pressure sufficient, which is then directed to the emergency valve, element no. 4.

Keep this container filled with water and protected from freezing.

Element 3 - burner

Element 4 - Emergency valve

The emergency valve consists of a plastic water canister with a screw cap and two adapters.

Empty car oil cans is a good improvisation.

The emergency valve is designed to intercept the flame to stop the reverse effect. An emergency valve is located between Element 3 - burner and gas collection container, Element 2.

It is imperative that you install an emergency valve to prevent the gas container from igniting, leading to an accident or explosion.