Do-it-yourself home biogas plant. Biogas

Farmers need fuel for heating systems, electricity generation and other daily needs. With energy prices rising steadily year after year, every homeowner or small business owner has at least once thought about how to produce biogas at home.

Biogas plants are increasingly being used on farms, saving money on heating

A biogas plant for a private house allows you to organize the production of biogas right in your yard, which solves the problem of fuel. Since a significant percentage of villagers have skills in working with welding and metalwork tools, the issue of self-manufacturing a gas production unit looks logical. So you can save not only on work, but also on materials, if you use improvised means.

What is biogas and how is it produced: production and production

Biogas is a substance produced during the fermentation of organic waste that contains enough methane to be used as a fuel. When burned, biogas releases heat, which is enough to heat a house or refuel a car. An energy source is manure, which is readily available and cheap or completely free, if we are talking about a livestock enterprise or a large private farm.

Biogas is an environmentally friendly biofuel that you can produce with your own hands, biological gas is related to natural gas. The gas is obtained as a result of the processing of waste by anaerobic bacteria. Fermentation takes place in the airless space of a container called a bioreactor. The rate of biogas production depends on the amount of waste loaded into the biogenerator. Under the action of bacteria, a mixture of methane and carbon dioxide with some impurities of other gaseous substances is released from the raw material. The resulting gas is removed from the bioreactor, purified and used for own needs. The processed raw material at the end of the process becomes a fertilizer that is used to improve soil fertility. Obtaining biogas is beneficial for livestock enterprises, which have access to free manure and other organic waste.

Advantages of burning fuel from manure (fertilizer on the farm) for heating: electricity from methane

The advantages of biogas as a fuel include:

Efficient and environmentally friendly recycling
Availability of feedstock for gas production in rural areas
Possibility to organize a closed cycle of non-waste production of gas and fertilizers from manure
Non-depleting self-replenishing source of raw materials

How to build a bioreactor (installation) with your own hands

Biogas plants that extract gas from manure can be easily assembled with your own hands on your own site. Before assembling a bioreactor for manure processing, it is worth drawing drawings and carefully studying all the nuances, because. A container containing a large amount of explosive gas can be a source of great danger if it is used incorrectly or if there are errors in the design of the installation.

Biogas scheme

The capacity of the bioreactor is calculated based on the amount of raw material that is used to produce methane. In order for the operating conditions to be optimal, the reactor vessel is filled with waste at least two-thirds. For these purposes, a deep hole is used. In order for the tightness to be high, the walls of the pit are reinforced with concrete or reinforced with plastic, sometimes concrete rings are installed in the pit. The surface of the walls is treated with moisture insulating solutions. Tightness is a necessary condition for the efficient operation of the installation. The better the container is insulated, the higher the quality and quantity. In addition, the decay products of the waste are toxic and, if leaked, can be harmful to health.

A stirrer is installed in the waste container. It is responsible for mixing the waste during fermentation, preventing uneven distribution of raw materials and the formation of a crust. Following the agitator, a drainage structure is mounted in the manure, which facilitates the removal of gas into the storage tank and prevents leakage. It is necessary to remove the gas for safety reasons, as well as to improve the quality of fertilizers remaining in the reactor after processing is completed. A hole is made at the bottom of the reactor for. The hole is equipped with a tight cover so that the equipment remains airtight.

How to ensure active fermentation of biomass at home using a generator and other equipment: waste processing, composition and extraction

In order for the processing process in the bioreactor to proceed faster, heating is necessary. The ambient temperature is quite enough for manure processing to take place without outside help. But under adverse weather conditions, in the winter season, a mini-biogas plant needs an additional heat source, otherwise gas production becomes impossible. In order for bacteria to turn waste into gas, the temperature in the reactor must be above 38 degrees Celsius. It is not difficult to get biogas with your own hands, the main thing is to know certain manufacturing rules.

The tank is heated using a coil, which is placed under the reactor, or by installing electric heaters for direct heating of the tank. , processing waste into gas, is already in the raw material. To activate microorganisms and start the biogas production process, the temperature in the tank must be sufficient for fermentation. To facilitate monitoring of compliance with temperature conditions, automatic heating is connected to the reactor. It heats the container when loading fuel into it to the desired temperature and turns off the heating when the desired mark on the thermometer is reached. The temperature control device for which is easy to find in a gas equipment store will cope with the role of an automatic heater.

Temperature control module. It can be purchased at any hardware store.

Correct removal of gas from the bioreactor: drawings, use of technology

For easy removal of the resulting gas from the tank, biogas plants are equipped with a number of devices:

Vertically arranged plastic pipes with a large number of holes to facilitate the separation of gas from the feedstock. The top of the pipe should protrude above the waste mass, allowing the gas to escape freely.
A film laid over a container and forming a semblance of a greenhouse effect. It maintains the desired temperature inside the tank, and also prevents the gas from mixing with air.

Sometimes the top of the container is covered with a dome made of concrete or other material. To prevent such a dome from flying away under the pressure of the resulting gas, it is carefully attached to the structure, tied with cables.
A gas outlet pipe is placed in the upper part of the reactor. The pipe is equipped with a tight locking mechanism so as not to violate the tightness of the structure. The newly released biogas, entering the outlet pipe, is saturated with water vapor and contains many impurities. occurs by condensation: cooling to ambient temperature, water settles in the form of condensate on the walls of the pipe. To avoid corrosion, the discharge pipe is installed in such a way as to facilitate the removal of condensate through the separator.
To rid biogas of hydrogen sulfide impurities, a filter of specially treated activated carbon is installed on its way to the storage, in which the mixture is oxidized to sulfur and settles in the sorbent.

WATCH VIDEO

A self-assembled biogas plant, processing manure into biogas at home, significantly reduces the cost of paying for heating and electricity. Such an installation will reduce the cost of providing a private house with heat, reduce the cost of farm products, thereby increasing the profitability of the economy. – the ability to turn waste into an energy source and an alternative to natural gas. Biogas is environmentally friendly and modern.

The growing popularity of alternative methods of obtaining heat and electricity has led to the desire of many owners of country houses and cottages to obtain a certain autonomy from external energy suppliers. Moreover, “purchased” energy shows a constant tendency to increase prices, and the maintenance of a country economy is getting more and more expensive every day. A biogas plant is an excellent alternative for external energy sources. At a minimum, it can provide the house with combustible gas for the stove, and with an increase in power (if there is enough of its own or purchased waste), it can provide both heating and electricity for both the house and the entire household.

Who needs biogas plants

Biogas plants are used to produce combustible gases from biological raw materials. So they are needed wherever combustible gases are required. That is, to obtain thermal and electrical energy.
First of all, biogas plants are necessary for those farms where there is a lot of raw materials in the form of biological waste. Thus, it is possible not only to make production waste-free, but also to significantly increase its profitability - due to independent energy production, the absence of costs for the purchase of both thermal and electrical energy.

Vladimir Rashin, a designer of a biogas plant and a farmer from Perm, proved from his own experience that agricultural production, which independently utilizes waste using an appropriate device, fully meets its needs for heat and electricity, as well as combustible gas. In his quail farm, biogas is used for heating premises (both residential and utility and industrial), for generating electricity, in kitchen stoves, as well as for refueling vehicles - all cars of the Rashin farm run on biogas. In this case, the main raw material for the biogas plant is quail manure. At the output, in addition to biogas, organic fertilizer is also obtained, which also brings additional income to the farm.

Biogas plants like Vladimir Rashin's can significantly increase the profitability of any agricultural production. As a raw material for biogas production, not only manure can be used, but also various waste products from woodworking industries (bark, sawdust, and so on), and almost any organic matter.

In addition, biogas plants can also be used in country houses and cottages, even if such farms do not have a farming orientation. Household waste from any farm will be enough to provide raw materials for an individual biogas plant, and if the farm is not fully provided with thermal and electrical energy, then at least reduce the cost of acquiring such energy. In addition, in addition to household waste, in any suburban economy there is also waste from a personal plot (weeds, cuttings of branches, and so on). Well, it is possible to provide a stove with combustible gas even with the help of a mini-biogas plant in country conditions.

The principle of obtaining biogas

Biogas is produced by anaerobic (that is, without oxygen) fermentation of biomass, which is provided by special bacteria. Three types of bacteria are involved in the process: hydrolytic, acid-forming and methane-forming.

The biogas plant consists of several parts (tanks). First, the raw material enters the preliminary tank, where it is thoroughly mixed and crushed (in the case of a solid fraction) to a homogeneous mass. Then the crushed raw material enters the reactor (a container where the biomass is directly fermented).

The reactor is usually made of acid-resistant reinforced concrete. This container is completely sealed. In order to speed up the fermentation process, the liquid in the container is heated and mixed. Most often, a cogeneration plant is used to heat the reactor - in such an installation, it is necessary to cool the heat and power generator, and the removed heat enters the reactor. Also, heat can come from a special hot water boiler.

After the fermentation process is completed, the generated gas from the reactor enters the gas holder, where the pressure is equalized, and then the biogas enters the heat and power generator (gas or diesel-gas), as a result of which thermal or electrical energy is produced.

In addition to biogas, a solid fraction is deposited in the reactor - organic fertilizers, which can then be used in the fields. Liquid fertilizers are also obtained from the reactor - after the release of gas. Both liquid and solid fertilizers are concentrated and are actively used in agriculture.

Industrial biogas plants have automatic control. Automation is responsible for the flow of raw materials into the installation, and for mixing, controls the temperature, the operation of the generator, and so on. Also, such installations are equipped with emergency flare devices - in case the engine stops, then the gas is simply burned. In addition, industrial biogas plants are often equipped with a line for packaging liquid fertilizers, in which case fertilizers are bottled into small (up to 1 liter) bottles.

Individual biogas plant

The principle of operation of an individual biogas plant is the same as that of an industrial one. True, mini-installations are rarely equipped with automatic devices for mixing the substrate and other automation - due to the significant increase in the cost of a household installation with such a configuration. Most often, these plants have only temperature control devices, generator operation, and so on, and all maintenance of the mini-biogas plant is carried out manually.

Household biogas plants are mainly used for the production of combustible gas for kitchen needs, if the farm does not have a livestock or crop-growing orientation. However, there is an increasing trend towards the use of mini-installations to provide country houses and cottages with a complete energy complex, that is, not only "kitchen" gas, but also thermal and electrical energy. Moreover, it no longer depends on the presence of large or small livestock on the farm, raw materials for home biogas plants are simply purchased from the nearest farm. It can be both manure and woodworking waste.

DIY biogas plant

The construction of biogas plants, even mini ones for domestic needs, is not cheap. And, although the payback period for such equipment is relatively short (5-7 years), not every owner is ready or has the opportunity to invest the required amount. Yes, the advantages are obvious: in a short time, with the help of a mini-biogas plant, you can get almost complete autonomy from purchased energy sources, transfer your farm to self-sufficiency, and even have free fertilizers as additional bonuses. However, you need to pay money today, and the advantages will appear only in a few years. Therefore, many owners of country houses and cottages are wondering: how to make a biogas plant on their own?

A mini biogas plant is not that complicated, and its construction is quite manageable. This saves a significant amount. In addition, there are projects of biogas plants using improvised means and materials (for example, with a bell reactor, moreover, the bell can be made of rubber, and so on). That is, home-made installations for the production of biogas is the acquisition of the desired bonuses for minimal money.

When building a biogas plant, it is necessary to make an accurate calculation - what should be its performance. To do this, all desired consumers of biogas should be taken into account (for example, a cooker, automotive equipment, etc.). If biogas is planned to be used to generate electricity and/or heat energy, then the calculation should include all energy consumers. Based on the calculation, a biogas plant project is created.

Homemade biogas plants are widely represented on the Internet. You can find sample calculations, and a drawing of the device, and a detailed description. A huge selection of devices will make it possible to manufacture both a complex installation with several chambers and a simplified version (for example, such a simple device as a cesspool covered with a rubber bell with a gas outlet device). Everyone will be able to choose a home-made installation in accordance with their desires, capabilities and skills. Particularly useful in this case are descriptions accompanied by step-by-step photographs or videos.

Making a biogas plant with your own hands allows you to save up to 50% of the cost of the device, which significantly speeds up the payback of equipment. In addition, making the simplest installation to start with allows you to assess the need for such equipment on the farm, as well as invest money gradually, which for many is much easier than paying the entire amount right away.

How does a biogas plant work?

Anyone can create biogas on their own. This does not require special knowledge and special skills in the field of renewable energy sources. If each person thinks about the world around him, the situation with the ecology on Earth will improve significantly.

Manure gas is a reality. It can indeed be obtained from manure, which in one way or another fertilizes the earth. But you can put it into circulation and get real gas.

To get gas from manure with your own hands at home, a farm biogas plant is used. You can extract natural gas using a digester right on the farm. This is how many farmers do it. For this, you do not need to purchase special fuel. Enough natural raw materials.

The bioreactor should include from 1 to 8-10 cubic meters. waste of private production, chicken manure. The production and processing of raw materials on a device with such a volume will be able to process more than 50 kg of manure. To make a biogas plant, you should find the drawings according to which the equipment is made, and you also need a diagram.

The operation of the installation is carried out in several stages:

Mixing of raw materials;

Heating;

Isolation of biogas.

A home-made installation will allow you to get gas from manure in a matter of time. It can be assembled independently, having diagrams and drawings. For the heat generator, you can choose boilers for heating water. To collect gas on the site you need a gas tank. It collects and stores gas.

Remember that impurities and debris in the tank should be cleaned from time to time.

You can get gas from manure using a biogas plant. It can be designed by hand. Determine the volume of processed raw materials, choose a suitable container in which the raw materials will be processed and mixed - this is how the production of gas saturated with methane in biofuel occurs.

Making biogas at home

There is a stereotype that biogas can only be obtained at specialized industries and farms. However, it is not. Today you can make biogas at home.

Biogas is a collection of various gases that are created by the decomposition of organic matter. It is worth knowing that biogas is flammable. It ignites easily with a pure flame.

We note the advantages of a biogas plant at home:

Obtaining biogas without expensive equipment;
Using your ;
Natural and free raw materials in the form of manure or plants;
Caring for the environment.

Having a biogas plant at home is a profitable business for the owner of a summer cottage. To make such an installation, a small amount of funds is needed: two barrels of 200 liters each, a barrel of 50 liters, sewer pipes, a gas hose and a tap.

As you can see, to do the installation yourself, you don’t even need to buy additional tools. Barrels, faucet, hoses and pipes can almost always be found on the farm of cottage owners. The gas generator is a concern for the environment, as well as your opportunity to use an alternative source of energy and fuel.

Why do you need a biogas plant for farming

Some farmers, summer residents, owners of private houses do not see the need to make a biogas plant. At first glance, it is. But then, when the owners see all the benefits, the question of the need for such an installation disappears.

The first obvious reason to make a biogas plant on a farm is to get electricity, heating, which will allow you to pay less for electricity.

Using your energy is cheaper than paying for its supply to the farm.

Another main reason for the need to create an installation is the organization of a complete cycle of non-waste production. As a raw material for the device, we use manure or droppings. After processing, we get new gas.

The third reason in favor of a biogas plant is the efficient processing and environmental impact.

3 advantages of a biogas plant:

Getting energy to keep the family farm running;
Organization of the completed cycle;
Efficient use of raw materials.

Having an installation on a farm is an indicator of your efficiency and concern for the world around you. Biogenerators save a huge amount of money by making production zero waste, efficient allocation of resources and raw materials, but also your complete self-sufficiency.

A heat pump is easy to assemble with your own hands from old home equipment. The whole process is described in the following article:

Question for an efficient economy: how to get methane correctly

Methane is the main component of biogas. Biogas itself is a mixture of various gases. Among them, methane is the most important.

Let's highlight the factors that affect the production of methane:

Environment;
Quality raw materials;
The frequency of mixing of raw materials in the installation tank.

Mix the raw materials in the container with a pitchfork and at least once a day, ideally - six times.

The production of methane is directly related to the production of biogas. The better you treat the process of obtaining biogas, the better you will get biogas at the output. To do this, you need to use only high-quality raw materials, monitor the place where the installation is located, and mix the contents of the tank. Then you will get methane correctly.

DIY biogas plant (video)

There are more and more supporters of preserving the environment in its original form. Without emissions and environmental pollution. Biogas plants solve this problem. In addition, the owner of the biogas plant personally receives direct monetary benefits from its use.

Energy consumption in the modern world is constantly growing, and raw materials are being depleted. Therefore, a person is increasingly using alternative fuels in everyday life, such as the energy of the sun, wind, water. Every year the world produces and accumulates tons of biological waste, the disposal of which takes a lot of money. But now there is a technology that allows you to process biowaste (primarily manure) and obtain environmentally friendly fuel - biogas. These technologies laid the foundation for the development of a new industry - bioenergy. For the production of ecological gas, special units are used - biogas plants.

What is biogas

Biogas is the gas that is released from the fermentation of biomass. It is a colorless and odorless substance that is 70% methane and 30% carbon dioxide. It has a very high heat output: when burning 1 m³ of biogas, the same amount of heat is released as when burning 1.5 kg of hard coal.

The release of biogas occurs under the influence of anaerobic bacteria, the activity of which increases when heated. They stimulate the decomposition of organic waste, resulting in the formation of biological gas.

However, not all biomasses are suitable for the production of this type of fuel. The most suitable raw material is cow manure, since cows eat only plant foods. But bird droppings and waste from pig farms cannot be used, since they are toxic. To obtain biogas, they have to be diluted.

In addition, waste from the production of juices, wines, milk, starch and molasses, waste from the processing of potatoes, grass, algae, household waste, etc. are used to produce biological gas.

Advantages and disadvantages

Biogas production has a number of undeniable advantages:

Effectively destroys waste and disinfects drains.
It has a beneficial effect on the ecological situation, as it prevents the release of methane into the atmosphere, which has a huge impact on the greenhouse effect.
Raw materials are inexhaustible and practically free, so the purchase of equipment becomes cost-effective.

Like any technology, biogas production is not perfect and has its drawbacks:

The speed of its production is largely inferior to traditional energy sources.
To maintain the reaction, a large number of enzymes of a certain quality are needed.
In case of violation of the tightness of containers with biogas, its quality is sharply reduced.

Where applicable

Biofuel is primarily used for household needs: cooking or space heating. Enterprises can use biogas for a closed production cycle, because the cost of this fuel competes with the cheapest nuclear energy.

Design and principle of operation of a biogas plant

Biogas plants are special units in which waste is processed with the formation of biogas and organic fertilizer.

They are manufactured in industry for large farms and enterprises, but if desired, the owner of a private house can also purchase such an installation for himself. However, for the latter, it will be beneficial only if he has daily access to a sufficient amount of organic waste, for example, he keeps his household plot.

The design and principle of operation of industrial and domestic installations are similar, the units differ only in their size and volume of fuel produced.

Biogas plants include:

Processing bunker.
system gas supply.
Supply and unloading of raw materials.
heating.
Stirring.

The principle of operation of the device is simple:

Waste diluted with water is loaded into the processing sealed bunker.
There, the waste is heated, activating bacteria, and begins to ferment, releasing gas.
Gas is collected in the upper part of the bunker and enters the gas collector through a special pipe, and from there to household appliances.
The contents of the bunker are systematically updated, adding fresh biomass and draining the waste.

Only fresh waste is suitable for loading into the device. It is ineffective to use already rotting raw materials. In addition, antibiotics, mold, tree resin, detergents and solvents must not be recycled.

How do biogas plants work: ( https://www.youtube.com/embed/mIwA9EN5J6o)

Biogas plants for home

The acquisition of industrial units will be expensive, and the payback in the household will be 7-10 years. This will require a large amount of organic waste. Therefore, it is much more profitable and more convenient to make a home biogas plant with your own hands. The materials for this will require the most affordable, and manufacturing technology is within the reach of any owner.

processing tank

Any hermetically sealed container of a cylindrical shape is suitable for it. These can be large pots or boiling pots, as well as plastic barrels with a volume of 10 liters. You can also use iron, but before that you need to treat them with an anti-corrosion compound and waterproof paint.

gas outlet

It is a pipe that is welded to the lid of the barrel. To communicate the tank with a gas outlet, a hole is cut at the installation site of the latter. Through a pipe, gas from the tank enters the storage tank, and from there to household appliances.

A special gas release valve should be installed next to the gas outlet, in case the pressure in the tank rises too much.

Feeding and unloading of raw materials

To supply fresh biomass and remove waste from the tank, two holes will need to be made in the tank. What is intended for unloading is best done at the very bottom. And for loading - higher. Pipes of the appropriate diameter are soldered into them.

The loading pipe should be directed upwards, and it is convenient to equip it with a funnel. And the pipe for draining the waste mass should be installed so that the drain occurs freely. Joints must be sealed.

Heating

If the biogas tank is to be placed outdoors, it is necessary to take care of its thermal insulation and heating system. For thermal insulation, it is enough to wrap the tank with a warming cloth or dig it into the ground.

You can use different options for organizing heating, for example:

Bring pipes from the heating system and arrange them in the form of a coil around the tank.
Place the tank inside another one filled with water, which is heated with shadows.

The optimum temperature for the reaction to proceed is 38 degrees. When it rises more than 55 degrees, the process may stop, since anaerobic bacteria will die.

Mixing

Mixing several times increases the efficiency of the process. To do this, it is necessary to install an axle with welded blades inside the tank, and bring the end of this axle to the cover and seal it. Then it must be equipped with a special handle.

Getting gas

Organic mass should be loaded into the finished installation and water should be added in a ratio of 2:3. Large waste must be shredded. Close the tank with a lid and wait for the start of fermentation. Usually the process starts in 2-3 days. This can be judged by the characteristic gurgling.

After two weeks, you need to add a fresh portion of raw materials and drain the spent batch. After a new batch enters through the loading pipe, the same amount of waste liquid will merge from the outlet pipe. It can be used to fertilize the soil in the garden. In the future, you will need to update the raw materials every two days.

DIY biogas plants: ( https://www.youtube.com/embed/Q8o9Ye8JcRY)

Please note that the use of even the simplest biogas equipment must be documented. Including, permission from the Sanitary and Epidemiological Station, fire and gas services must be obtained.

Biogas production technology. Modern livestock complexes provide high production rates. The applied technological solutions allow to fully comply with the requirements of the current sanitary and hygienic standards in the premises of the complexes themselves.

However, large amounts of liquid manure concentrated in one place create significant environmental problems for the territories adjacent to the complex. For example, fresh pig manure and droppings are classified as hazard class 3 waste. Environmental issues are under the control of supervisory authorities, the requirements of the legislation on these issues are constantly tightened.

Biocomplex offers a comprehensive solution for the disposal of liquid manure, which includes accelerated processing in modern biogas plants (BGU). In the process of processing, in an accelerated mode, natural processes of decomposition of organic matter proceed with the release of gas, including: methane, CO2, sulfur, etc. Only the resulting gas is not released into the atmosphere, causing a greenhouse effect, but is sent to special gas-generating (cogeneration) installations that produce electrical and thermal energy.

Biogas - combustible gas, formed during anaerobic methane digestion of biomass and consisting mainly of methane (55-75%), carbon dioxide (25-45%) and impurities of hydrogen sulfide, ammonia, nitrogen oxides and others (less than 1%).

The decomposition of biomass occurs as a result of chemical and physical processes and the symbiotic activity of the 3 main groups of bacteria, while the metabolic products of some groups of bacteria are food products of other groups, in a certain sequence.

The first group - hydrolytic bacteria, the second - acid-forming, the third - methane-forming.

Both organic agro-industrial or household waste, and vegetable raw materials can be used as raw materials for the production of biogas.

The most common types of agro-industrial complex waste used for biogas production are:

pig and cattle manure, poultry droppings;
leftovers from the feed table of cattle complexes;
tops of vegetable crops;
substandard crop of cereals and vegetables, sugar beet, corn;
pulp and molasses;
flour, pellet, fine grain, embryos;
beer grains, malt sprouts, protein sludge;
waste of starch-treacle production;
pomace fruit and vegetable;
serum;
etc.

Raw material source	Type of raw material	Quantity of raw materials per year, m3 (tons)	Amount of biogas, m3
1 cash cow	Bedless liquid manure
1 fattening pig	Bedless liquid manure
1 fattening bull	Bedding solid manure
1 horse	Bedding solid manure
100 chickens	Dry litter
1 ha of arable land	Fresh corn silage
1 ha of arable land	Sugar beet
1 ha of arable land	Fresh grain silage
1 ha of arable land	Fresh grass silage

The number of substrates (types of waste) used for biogas production within one biogas plant (BGU) can vary from one to ten or more.

Biogas projects in the agro-industrial sector can be created according to one of the following options:

production of biogas from the waste of an individual enterprise (for example, manure from a livestock farm, bagasse from a sugar factory, stillage from a distillery);
biogas production on the basis of waste from different enterprises, with the linkage of the project to a separate enterprise or a separately located centralized biogas plant;
biogas production with the predominant use of energy plants at separately located biogas plants.

The most common way of energy use of biogas is combustion in gas piston engines as part of a mini-CHP, with the production of electricity and heat.

Exist various options for technological schemes of biogas stations- depending on the types and number of types of substrates used. The use of preliminary preparation, in a number of cases, makes it possible to achieve an increase in the rate and degree of decomposition of raw materials in bioreactors, and, consequently, an increase in the total biogas yield. In the case of using several substrates that differ in properties, for example, liquid and solid waste, their accumulation, preliminary preparation (separation into fractions, grinding, heating, homogenization, biochemical or biological treatment, etc.) is carried out separately, after which they are either mixed before feed into bioreactors, or are fed in separate streams.

The main structural elements of a typical biogas plant layout are:

system for receiving and preliminary preparation of substrates;
a system for transporting substrates within the facility;
bioreactors (fermenters) with a mixing system;
bioreactor heating system;
system for removal and purification of biogas from impurities of hydrogen sulfide and moisture;
storage tanks for fermented mass and biogas;
system of program control and automation of technological processes.

BGU technological schemes vary depending on the type and number of processed substrates, on the type and quality of the final target products, on one or another “know-how” of the technological solution supplier used, and a number of other factors. The most common today are schemes with single-stage fermentation of several types of substrates, one of which is usually manure.

With the development of biogas technologies, the technical solutions used are becoming more complex towards two-stage schemes, which in some cases is justified by the technological need for efficient processing of certain types of substrates and an increase in the overall efficiency of using the working volume of bioreactors.

Feature of biogas production is that it can be produced by methane bacteria only from absolutely dry organic substances. Therefore, the task of the first stage of production is to create a substrate mixture that has a high content of organic matter, and at the same time can be pumped. This is a substrate with a solids content of 10-12%. The solution is achieved by separating excess moisture using screw separators.

Liquid manure enters the tank from the production facilities, is homogenized with a submersible mixer, and is fed by a submersible pump to the separation shop for screw separators. The liquid fraction is collected in a separate tank. The solid fraction is loaded into the solid raw material feeder.

In accordance with the schedule for loading the substrate into the fermenter, according to the developed program, the pump is periodically turned on, supplying the liquid fraction to the fermenter, and at the same time the loader of the solid raw material is turned on. Alternatively, the liquid fraction can be fed into a solid feeder with a mixing function, and then the finished mixture is fed into the fermenter according to the developed loading program. Inclusions are short. This is done to prevent excessive input of organic substrate into the fermenter, as this can upset the balance of substances and cause destabilization of the process in the fermenter. At the same time, pumps are also switched on, pumping the digestate from the fermenter to the after-fermenter and from the after-fermenter into the digestate accumulator (lagoon), in order to prevent overfilling of the fermenter and after-fermenter.

The digestate masses located in the fermenter and after-fermenter are mixed to ensure an even distribution of bacteria throughout the volume of the containers. For mixing, low-speed mixers of a special design are used.

In the process of finding the substrate in the fermenter, bacteria release up to 80% of the total biogas produced by the biogas plant. The rest of the biogas is released in the conditioner.

An important role in ensuring a stable amount of biogas released is played by the temperature of the liquid inside the fermenter and after-fermenter. As a rule, the process proceeds in the mesophilic mode with a temperature of 41-43°C. Maintaining a stable temperature is achieved by using special tubular heaters inside the fermenters and fermenters, as well as reliable thermal insulation of walls and pipelines. Biogas leaving the digestate has a high sulfur content. Biogas purification from sulfur is carried out with the help of special bacteria that inhabit the surface of the insulation laid on a wooden beam vault inside the fermenters and after-fermenters.

The accumulation of biogas is carried out in a gas holder, which is formed between the surface of the digestate and the elastic high-strength material covering the fermenter and the fermenter from above. The material has the ability to stretch strongly (without reducing strength), which significantly increases the capacity of the gas tank with the accumulation of biogas. To prevent overfilling of the gas tank and rupture of the material, there is a safety valve.

The biogas then enters the cogeneration plant. A cogeneration plant (CHP) is a unit in which electrical energy is generated by generators driven by gas piston engines running on biogas. Cogenerators running on biogas have structural differences from conventional gas generator engines, since biogas is a very depleted fuel. The electrical energy generated by the generators provides power to the electrical equipment of the biogas plant itself, and everything in excess of this is released to nearby consumers. The energy of the liquid used to cool the cogenerators is the generated thermal energy minus the losses in the boiler devices. The generated thermal energy is partly used to heat fermenters and after-fermenters, and the rest is also sent to nearby consumers. goes to

It is possible to install additional equipment for cleaning biogas to the level of natural gas, however, this equipment is expensive and is used only if the purpose of the biogas plant is not to produce heat and electricity, but to produce fuel for gas piston engines. The proven and most commonly used biogas treatment technologies are water absorption, pressurized carrier adsorption, chemical precipitation and membrane separation.

The energy efficiency of biogas plant operation largely depends both on the chosen technology, materials and design of the main structures, and on the climatic conditions in the area of their location. The average consumption of thermal energy for heating bioreactors in the temperate climate zone is 15-30% of the energy generated by cogenerators (gross).

The overall energy efficiency of a biogas complex with biogas-fired CHP is 75-80% on average. In a situation where all the heat received from a cogeneration plant in the production of electricity cannot be consumed (a common situation due to the lack of external heat consumers), it is discharged into the atmosphere. In this case, the energy efficiency of a biogas thermal power plant is only 35% of the total biogas energy.

The main performance indicators of biogas plants can vary significantly, which is largely determined by the substrates used, the adopted technological regulations, operating practices, and the tasks performed by each individual plant.

The process of manure processing is no more than 40 days. The digestate obtained as a result of processing is odorless and is an excellent organic fertilizer, in which the highest degree of mineralization of nutrients absorbed by plants has been achieved.

Digestate is usually separated into liquid and solid fractions using screw separators. The liquid fraction is sent to the lagoons, where it is accumulated until the period of application to the soil. The solid fraction is also used as fertilizer. If additional drying, granulation and packaging is applied to the solid fraction, then it will be suitable for long-term storage and transportation over long distances.

Production and energy use of biogas has a number of reasonable and confirmed by world practice advantages, namely:

Renewable energy source (RES). Renewable biomass is used to produce biogas.
A wide range of raw materials used for biogas production makes it possible to build biogas plants virtually everywhere in areas of concentration of agricultural production and technologically related industries.
The versatility of biogas energy use methods both for the production of electrical and / or thermal energy at the place of its formation, and at any facility connected to the gas transmission network (in the case of supplying purified biogas to this network), as well as as motor fuel for cars.
The stability of electricity production from biogas throughout the year makes it possible to cover peak loads in the network, including in the case of the use of unstable renewable energy sources, such as solar and wind power plants.
Creation of jobs through the formation of a market chain from biomass suppliers to the operating personnel of energy facilities.
Reducing the negative impact on the environment through the processing and neutralization of waste through controlled digestion in biogas reactors. Biogas technologies are one of the main and most rational ways of neutralizing organic waste. Biogas projects help reduce greenhouse gas emissions into the atmosphere.
The agrotechnical effect of the use of the mass fermented in biogas reactors on agricultural fields is manifested in improving the structure of soils, regenerating and increasing their fertility due to the introduction of nutrients of organic origin. The development of the market for organic fertilizers, including from the mass processed in biogas reactors, in the future will contribute to the development of the market for environmentally friendly agricultural products and increase its competitiveness.

Estimated unit investment costs

BSU 75 kWel. ~ 9.000 €/kWh.

BSU 150 kWel. ~ 6.500 €/kWh.

BSU 250 kWel. ~ 6.000 €/kWh.

BSU bis 500 kWel. ~ 4.500 €/kWh.

BGU 1 MWtel. ~ 3.500 €/kWh.

The generated electrical and thermal energy can provide not only the needs of the complex, but also the adjacent infrastructure. Moreover, raw materials for biogas plants are free, which ensures high economic efficiency after the payback period (4-7 years) is over. The cost of energy generated at BSU does not increase over time, but on the contrary, it decreases.