Do-it-yourself biogas plant: Internet myths and rural reality. Biogas from manure: how profitable it is and how to make Biogas with your own hands at home

30.10.202327.05.2017

Required mandatory materials:

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

Desirable:

stirrer with electric motor;
temperature sensor;
pressure meter;

The sequence below is suitable for the southern regions. For operation under any conditions, a reactor heating system should be added, which will ensure heating of the vessel to 40 degrees Celsius and increase thermal insulation, for example, by enclosing the structure with a greenhouse. It is advisable to cover the greenhouse with black film. It is also advisable to add a condensate drainage device to the pipeline.

Creating a simple biogas plant:

Create a storage container. 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.
Insulate the structure inside the pit.
Install pipes. Lay pipes into the pit for loading raw materials and unloading compost humus. An inlet and outlet hole are made in the reactor tank. The reactor is placed in a pit. Pipes are connected to the holes. The pipes are tightly secured using glue or other suitable means. Pipe diameters less than 30 cm will contribute to their clogging. The loading location should be chosen on the sunny side.
Install the hatch. The rector, equipped with a hatch, makes repair and maintenance work more convenient. The hatch and reactor vessel should be sealed with rubber. You can also install temperature, pressure and raw material level sensors.
Select a container for the bioreactor. The selected container must be durable - since fermentation releases a large amount of energy; have good thermal insulation; be air and waterproof. Egg-shaped vessels are best suited. If building such a reactor is problematic, 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.
Prepare the pit.
Select a location for mounting the future installation. It is advisable to choose a place far enough from the house and so that you can dig a hole. Placing it inside a pit allows you to significantly save on thermal insulation, using cheap materials like clay.
Check the tightness of the resulting structure.
Start the system.
Add raw materials. We wait about two weeks until all the necessary processes take place. A necessary condition for gas combustion is to get rid of carbon dioxide. A regular filter from a hardware store will do for this. A homemade filter is made from a 30 cm long piece of gas pipe filled with dry wood and metal shavings.

Composition and types

Biogas is a gas obtained as a result of a three-phase biochemical process on biomass, taking place in sealed conditions.

The process of biomass decomposition is sequential: first it is exposed to hydrolytic bacteria, then acid-forming bacteria and finally methane-forming bacteria. 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 (30 to 40%);
hydrogen sulfide (~2%);
hydrogen (~1%);
ammonia (~1%);

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

Ancient cultures dating back more than three thousand years (India, Persia or Assyria) have experience using flammable swamp gas. The scientific basis was formed much later. The chemical formula of methane CH 4 was discovered by scientist John Dalton, and the presence of methane in swamp gas was discovered by Humphry Davy. The Second World War played a major role in the development of the alternative energy industry, requiring the warring parties to have a huge need for energy resources.

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

Installation device

– a set of equipment designed to produce biogas from organic raw materials.

Based on the type of raw material supplied, the following types of biogas plants are distinguished:

with portioned feeding;
with continuous feed;

Biogas plants with a constant supply of raw materials are more efficient.

By type of raw material processing:

No automatic stirring raw materials and maintaining the required temperature - complexes with minimal equipment, suitable for small farms (Diagram 1).
With automatic stirring, but without maintaining the required temperature - also serves small farms, more efficiently than the previous type.
With support for the required temperature, but without automatic mixing.
With automatic mixing of raw materials and temperature support.

Principle of operation

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

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

It is necessary to mix the contents 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 gas tank and from there it is delivered to the consumer through pipes. Biofertilizers obtained after processing the feedstock 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:

homogenization tank;
reactor;
stirrers;
storage tank (gas-holder);
heating and water mixing complex;
gas complex;
pump complex;
separator;
control sensors;
Instrumentation and automation with visualization;
safety system;

An example of an industrial-type biogas plant is shown in Diagram 2.

Raw materials used

The decomposition of any animal or plant matter will release flammable gas to varying degrees. Mixtures of various compositions are well suited for raw materials: manure, straw, grass, various wastes, etc. The chemical reaction requires a humidity of 70%, so the raw material must be diluted with water.

The presence of cleaning agents, chlorine, and washing powders in organic biomass is unacceptable, as they interfere with chemical reactions and can damage the reactor. Also not suitable for the reactor are raw materials with sawdust from coniferous trees (containing resins), with a high proportion of lignin and exceeding the moisture threshold of 94%.

Vegetable. Plant raw materials are excellent for biogas production. Fresh grass gives the maximum fuel yield - about 250 m 3 of gas with a methane share of 70% is obtained from a ton of raw material. Corn silage is slightly smaller - 220 m3. Beet tops – 180 m3.

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

Animal. Waste from processing plants, dairy plants, slaughterhouses, etc. Suitable for biogas plant. The maximum fuel yield is provided by animal fats - 1500 m 3 of biogas with a methane share of 87%. The main disadvantage is shortage. Animal raw materials must also be ground.

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 processed immediately. The production cycle will take approximately two weeks and will produce an output of 60 m3 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 is not suitable since the fecal content is low.

Schemes of work

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

Scheme 2 – industrial biogas plant:

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

Practice says that to heat a living space with an area of 50 m2, it is necessary to consume 3.5 m3 of gas per hour.
It is not advisable to use biogas directly for cooking, because the taste may change.
It is necessary to avoid getting solid objects (nuts, bolts, etc.) into the raw materials, because the equipment may deteriorate.

In order for biogas to burn stably, it must meet certain standards:

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

If the gas goes out due to a pressure surge or for other reasons, and its supply continues, it can lead to tragic consequences. Therefore, modern equipment with gas monitoring sensors should be used.

A DIY biogas plant can be done without much effort. Its use will allow significant savings on energy resources, which today are becoming more and more expensive every time. If you independently decide to build equipment that allows you to obtain biogas from waste, you will be able to consume cheap energy, which will be used for heating your home and other needs.

Beneficial use

If during the operation of the installation excess biogas or fertilizers are generated, then it is possible to sell them at the market price, thereby turning what is literally lying under your feet into profit. If you are a large farmer, then you have the opportunity to purchase a ready-made biogas production station. Such factory-produced installations are very expensive, but have a long lifespan.

A do-it-yourself biogas plant can be made from scrap materials, it will not cost very much, and such equipment will work on the same principle. In this case, you can use available tools, as well as parts available in the master’s arsenal.

Principle of biogas formation

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

A do-it-yourself biogas plant for home using 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 remaining gaseous components are contained in the mass in an amount of 5%. Among the latter, hydrogen sulfide can be isolated in small quantities. The gas thus formed is continuously removed from the reactor, and after undergoing a purification process, it is used for its intended purpose.

Service Features

Waste that has undergone processing becomes high-quality fertilizers, which from time to time must be removed from the bioreactor. They can be laid on the fields. A DIY biogas plant can be done without much effort if you have access to livestock and agricultural facilities. This indicates that the production of biogas will become economically profitable 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 make a biogas plant yourself, you need to understand what parts it consists of. You can take as a basis the simplest diagram of equipment that you can build on your own. The design does not provide heating and a mixing device, but there is one of the main parts - a reactor, which is also known as a digester. This component is required for manure processing. In addition, there is a bunker through which raw materials are loaded. It is necessary to equip 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. A similar element will be required in order to realize the possibility of removing biogas.

This is what the diagram of a biogas plant looks like. It is not difficult to make such a design with your own hands. In order to receive free biological fuel, you should choose a place on the site where you can build a reinforced container, which will be based on concrete. This vessel will act as a bioreactor. At its base, it is necessary to provide a hole through which processed raw materials will be removed. This hole must be made in such a way that it can be closed well. This is due to the fact that the system can only operate 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 material will appear on a farm or private farm every day. But you should not save, since it will be possible to ensure full operation of the bioreactor only if you fill the tank to 2/3 of the available volume. If you make a biogas plant with your own hands from a barrel, it will work according to the following principle: as soon as organic waste enters a well-closed bioreactor container, which is located deep in the soil, it begins to ferment, which leads to the release of biogas.

Features of container manufacturing

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 you need to choose a metal vessel, guided by certain rules.

First of all, you need to pay attention to the welds, which must be strong enough and airtight. When using a small container, you should not expect to obtain a significant amount of biogas. The yield will depend on the mass of organic waste that is simultaneously processed 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 the home can be made in such a way that its operation can be more efficient. This is ensured by heating. Such manipulations will speed up the process of fermentation of biological mass. If the equipment is installed in the southern regions, then such a need does not arise. The ambient temperature provides natural activation of fermentation. However, if the installation operates in regions with a cold climate, then in winter heating acts as a necessary condition 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 do-it-yourself biogas plant for your home can be equipped with heating using several methods. The first involves the need to connect the installation to a heating system using a coil type. It must be mounted under the reactor. The second method involves installing an electric heating element at the base of the tank. The third method is characterized by providing direct heating of the tank by using electric heating systems and gas equipment. Activation of biological gas production at home can be supplemented with the function of mixing the mass in the compartment. To do this, you should design a device that resembles a household mixer. It will be driven by a shaft brought out through a hole in the lid; as an alternative solution, it can be placed in the walls of the tank.

Equipment of the installation with an output system

A mini biogas plant, designed with your own hands, cannot operate without a gas exhaust system. To do this, the installation must have a special hole, which must be mounted in the upper part of the lid, the latter must cover the tank well. To eliminate the possibility of gas mixing with air, it is necessary to ensure its removal through a water seal.

One of the problems that has to be solved in agriculture is the disposal of manure and plant waste. And this is a rather serious problem that requires constant attention. Recycling takes not only time and effort, but also considerable amounts. Today there is at least one way to turn this headache into an income source: processing manure into biogas. The technology is based on the natural process of decomposition of manure and plant residues due to the bacteria they contain. The whole task is to create special conditions for the most complete decomposition. These conditions are the absence of oxygen access and optimal temperature (40-50 o C).

Everyone knows how manure is most often disposed of: they put it in heaps, then, after fermentation, they take it out to the fields. In this case, the resulting gas is released into the atmosphere, and 40% of the nitrogen contained in the initial substance and most of the phosphorus also escape there. The resulting fertilizer is far from ideal.

To obtain biogas, it is necessary that the process of decomposition of manure takes place without access to oxygen, in a closed volume. In this case, both nitrogen and phosphorus remain in the residual product, and the gas accumulates in the upper part of the container, from where it can be easily pumped out. There are two sources of profit: gas directly and effective fertilizer. Moreover, the fertilizer is of the highest quality and 99% safe: most of the pathogenic microorganisms and helminth eggs die, and the weed seeds contained in the manure lose their viability. There are even lines for packaging this residue.

The second prerequisite for the process of processing manure into biogas is maintaining an optimal temperature. The bacteria contained in the biomass are inactive at low temperatures. They begin to act at an ambient temperature of +30 o C. Moreover, manure contains two types of bacteria:

Thermophilic plants with temperatures from +43 o C to +52 o C are the most effective: in them, manure is processed for 3 days, and the output from 1 liter of useful bioreactor area is up to 4.5 liters of biogas (this is the maximum output). But maintaining a temperature of +50 o C requires significant energy expenditure, which is not profitable in every climate. Therefore, biogas plants often operate at mesophilic temperatures. In this case, the processing time can be 12-30 days, the yield is approximately 2 liters of biogas per 1 liter of bioreactor volume.

The composition of the gas varies depending on the raw materials and processing conditions, but it is approximately as follows: methane - 50-70%, carbon dioxide - 30-50%, and also contains a small amount of hydrogen sulfide (less than 1%) and very small amounts of ammonia, hydrogen and nitrogen compounds. Depending on the design of the plant, biogas may contain a significant amount of water vapor, which will require drying (otherwise it simply will not burn). What an industrial installation looks like is demonstrated in the video.

This can be said to be an entire gas production plant. But for a private farmstead or small farm such volumes are useless. The simplest biogas plant is easy to make with your own hands. But the question is: “Where should the biogas be sent next?” The heat of combustion of the resulting gas is from 5340 kcal/m3 to 6230 kcal/m3 (6.21 - 7.24 kWh/m3). Therefore, it can be supplied to a gas boiler to generate heat (heating and hot water), or to an electricity generation installation, to a gas stove, etc. This is how Vladimir Rashin, a biogas plant designer, uses manure from his quail farm.

It turns out that if you have at least a decent amount of livestock and poultry, you can fully meet your farm’s needs for heat, gas and electricity. And if you install gas installations on cars, then it will also provide fuel for the fleet. Considering that the share of energy resources in the cost of production is 70-80%, you can only save on a bioreactor, and then earn a lot of money. Below is a screenshot of an economic calculation of the profitability of a biogas plant for a small farm (as of September 2014). The farm cannot be called small, but it is definitely not large either. We apologize for the terminology - this is the author's style.

This is an approximate breakdown of the required costs and possible income Schemes for homemade biogas plants

Schemes of homemade biogas plants

The simplest scheme of a biogas plant is a sealed container - a bioreactor, into which the prepared slurry is poured. Accordingly, there is a hatch for loading manure and a hatch for unloading processed raw materials.

The simplest scheme of a biogas plant without any bells and whistles

The container is not completely filled with the substrate: 10-15% of the volume should remain free to collect gas. A gas outlet pipe is built into the tank lid. Since the resulting gas contains a fairly large amount of water vapor, it will not burn in this form. Therefore, it is necessary to pass it through a water seal to dry it. In this simple device, most of the water vapor will condense, and the gas will burn well. Then it is advisable to clean the gas from non-flammable hydrogen sulfide and only then can it be supplied to a gas holder - a container for collecting gas. And from there it can be distributed to consumers: fed to a boiler or gas oven. Watch the video to see how to make filters for a biogas plant with your own hands.

Large industrial installations are placed on the surface. And this, in principle, is understandable - the volume of land work is too large. But on small farms the bunker bowl is buried in the ground. This, firstly, allows you to reduce the cost of maintaining the required temperature, and secondly, in a private backyard there are already enough all kinds of devices.

The container can be taken ready-made, or made from brick, concrete, etc. in a dug pit. But in this case, you will have to take care of the tightness and impermeability of air: the process is anaerobic - without air access, therefore it is necessary to create a layer impenetrable to oxygen. The structure turns out to be multi-layered and the production of such a bunker is a long and expensive process. Therefore, it is cheaper and easier to bury a ready-made container. Previously, these were necessarily metal barrels, often made of stainless steel. Today, with the advent of PVC containers on the market, you can use them. They are chemically neutral, have low thermal conductivity, a long service life, and are several times cheaper than stainless steel.

But the biogas plant described above will have low productivity. To activate the processing process, active mixing of the mass located in the hopper is necessary. Otherwise, a crust forms on the surface or in the thickness of the substrate, which slows down the decomposition process, and less gas is produced at the outlet. Mixing is carried out in any available way. For example, as demonstrated in the video. In this case, any drive can be made.

There is another way to mix the layers, but it is non-mechanical - barbitation: the generated gas is fed under pressure into the lower part of the container with manure. Rising upward, gas bubbles will break the crust. Since the same biogas is supplied, there will be no changes in processing conditions. Also, this gas cannot be considered a consumption - it will again end up in the gas tank.

As mentioned above, good performance requires elevated temperatures. In order not to spend too much money on maintaining this temperature, you need to take care of insulation. What type of heat insulator to choose, of course, is up to you, but today the most optimal one is polystyrene foam. It is not afraid of water, is not affected by fungi and rodents, has a long service life and excellent thermal insulation performance.

The shape of the bioreactor can be different, but the most common is cylindrical. It is not ideal from the point of view of the complexity of mixing the substrate, but it is used more often because people have accumulated a lot of experience in building such containers. And if such a cylinder is divided by a partition, then they can be used as two separate tanks in which the process is shifted in time. In this case, a heating element can be built into the partition, thus solving the problem of maintaining temperature in two chambers at once.

In the simplest version, homemade biogas plants are a rectangular pit, the walls of which are made of concrete, and for tightness they are treated with a layer of fiberglass and polyester resin. This container is equipped with a lid. It is extremely inconvenient to use: heating, mixing and removal of the fermented mass is difficult to implement, and it is impossible to achieve complete processing and high efficiency.

The situation is a little better with trench biogas manure processing plants. They have beveled edges, making it easier to load fresh manure. If you make the bottom at a slope, then the fermented mass will shift to one side by gravity and it will be easier to select it. In such installations, it is necessary to provide thermal insulation not only for the walls, but also for the lid. It is not difficult to implement such a biogas plant with your own hands. But complete processing and the maximum amount of gas cannot be achieved in it. Even with heating.

The basic technical issues have been dealt with, and you now know several ways to build a plant for producing biogas from manure. There are still technological nuances.

What can be recycled and how to achieve good results

The manure of any animal contains the organisms necessary for its processing. It has been discovered that more than a thousand different microorganisms are involved in the fermentation process and gas production. Methane-forming substances play the most important role. It is also believed that all these microorganisms are found in optimal proportions in cattle manure. In any case, when processing this type of waste in combination with plant matter, the largest amount of biogas is released. The table shows average data for the most common types of agricultural waste. Please note that this amount of gas output can be obtained under ideal conditions.

For good productivity it is necessary to maintain a certain substrate humidity: 85-90%. But water must be used that does not contain foreign chemicals. Solvents, antibiotics, detergents, etc. have a negative effect on processes. Also, for the process to proceed normally, the liquid should not contain large fragments. Maximum fragment sizes: 1*2 cm, smaller ones are better. Therefore, if you plan to add herbal ingredients, you need to grind them.

It is important for normal processing in the substrate to maintain an optimal pH level: within 6.7-7.6. Usually the environment has normal acidity, and only occasionally acid-forming bacteria develop faster than methane-forming bacteria. Then the environment becomes acidic, gas production decreases. To achieve the optimal value, add regular lime or soda to the substrate.

Now a little about the time it takes to process manure. In general, the time depends on the conditions created, but the first gas can begin to flow already on the third day after the start of fermentation. The most active gas formation occurs when manure decomposes by 30-33%. To give you a sense of time, let’s say that after two weeks the substrate decomposes by 20-25%. That is, optimally the processing should last a month. In this case, the fertilizer is of the highest quality.

Calculation of bin volume for processing

For small farms, the optimal installation is a constant one - this is when fresh manure is supplied in small portions daily and removed in the same portions. In order for the process not to be disrupted, the share of the daily load should not exceed 5% of the processed volume.

Homemade installations for processing manure into biogas are not the pinnacle of perfection, but are quite effective

Based on this, you can easily determine the required tank volume for a homemade biogas plant. You need to multiply the daily volume of manure from your farm (already in a diluted state with a humidity of 85-90%) by 20 (this is for mesophilic temperatures, for thermophilic temperatures you will have to multiply by 30). To the resulting figure you need to add another 15-20% - free space for collecting biogas under the dome. You know the main parameter. All further costs and system parameters depend on which biogas plant scheme is chosen for implementation and how you will do everything. It is quite possible to make do with improvised materials, or you can order a turnkey installation. Factory developments will cost from 1.5 million euros, installations from the Kulibins will be cheaper.

Legal registration

The installation will have to be coordinated with the SES, gas inspectorate and firefighters. You will need:

Technological diagram of the installation.
Layout plan for equipment and components with reference to the installation itself, the installation location of the thermal unit, the location of pipelines and energy mains, and pump connections. The diagram should indicate the lightning rod and access roads.
If the installation will be located indoors, then a ventilation plan will also be required, which will provide at least an eightfold exchange of all the air in the room.

As we see, we cannot do without bureaucracy here.

Finally, a little about the performance of the installation. On average, per day a biogas plant produces a volume of gas twice the useful volume of the reservoir. That is, 40 m 3 of slurry will produce 80 m 3 of gas per day. Approximately 30% will be spent on ensuring the process itself (the main expense item is heating). Those. at the output you will receive 56 m 3 of biogas per day. According to statistics, to cover the needs of a family of three and to heat an average-sized house, 10 m 3 is required. In net balance you have 46 m3 per day. And this is with a small installation.

Results

By investing a certain amount of money in setting up a biogas plant (with your own hands or on a turnkey basis), you will not only meet your own needs and needs for heat and gas, but will also be able to sell gas, as well as high-quality fertilizers resulting from processing.

Every year on our planet energy resources become less and less. It is because of this that we have to constantly look for new, alternative sources of energy. Definitely, after some time our planet will run out of oil and gas deposits, and then the world will have to seriously think about the extraction (collection) and use of biogases as the main source of energy.

What is biogas? Principles of biogas production

As already mentioned, biogas is an alternative source of energy. It is released during the fermentation of various household wastes, as well as waste excreted by animals (manure).

This method has been used since ancient times in China, but later, centuries later, it was unclaimed and as a result was forgotten.

Do-it-yourself biogas production at home

Step 1: Selecting a Barrel

First we need to choose a suitable barrel in which we will store the “energy source”, that is, as you understand, food waste and manure.

Step 2: Making the holes

We make holes at the inlet and outlet of the barrel. It can be done using a drill, but in this case, the hole is made using a heated metal pipe.

Step 3: Installation of pipes

We install pipes at the inlet and outlet into the holes we made earlier. We insert and glue the pipes.

Step 4: Creating and installing a “gas tank” holder

We took a 20-liter paint bucket; this tank will contain the gas we extract. The tank is secured with a valve that plumbers use.

Step 5: Add Cow Manure

Mix cow dung (5 kg per 50 liters) and add water. Place it in the tank.

Step 6: Almost done

You will not receive gas for the first 10-15 days, as this time is necessary for all the necessary processes to go through.

Step 7: Get Rid of Carbon Dioxide

In order for this gas to burn, it is necessary to get rid of carbon dioxide. This can be achieved by using a regular filter, of which there are many in various hardware stores.

Step 8: Done!

You will notice how the “fuel tank” will rise as chemical reactions occur. Then it is necessary to open the valve and obtain biogas.

Biogas can be used for different purposes. It is not recommended to use biogas for cooking, as it can negatively affect the taste (if the flavors are not removed).

Video Lesson: Biogas production at home

Ecology of consumption. Estate: Is it profitable to produce biofuel at home in small quantities on a private plot? If you have several metal barrels and other iron junk, as well as a lot of free time and you don’t know how to manage it - yes.

Suppose there was no natural gas in your village and there never will be. And even if there is, it costs money. Although it is an order of magnitude cheaper than costly heating with electricity and liquid fuel. The nearest pellet production workshop is a couple of hundred kilometers away, and transport is expensive. It’s becoming more and more difficult to buy firewood every year, and it’s also troublesome to burn with it. Against this background, the idea of obtaining free biogas in your own backyard from weeds, chicken droppings, manure from your favorite pig or the contents of the owner’s outhouse looks very tempting. All you have to do is make a bioreactor! On TV they talk about how thrifty German farmers keep themselves warm with “manure” resources and now they don’t need any “Gazprom”. This is where the saying “takes the film off feces” is true. The Internet is replete with articles and videos on the topic “biogas from biomass” and “do-it-yourself biogas plant.” But we know little about the practical application of the technology: everyone is talking about the production of biogas at home, but few people have seen concrete examples in the village, as well as the legendary Yo-Mobile on the road. Let's try to figure out why this is so and what are the prospects for progressive bioenergy technologies in rural areas.

What is biogas + a little history

Biogas is formed as a result of sequential three-stage decomposition (hydrolysis, acid and methane formation) of biomass by various types of bacteria. The useful combustible component is methane, and hydrogen may also be present.

The process of bacterial decomposition that produces flammable methane

To a greater or lesser extent, flammable gases are formed during the decomposition of any remains of animal and plant origin.

The approximate composition of biogas, the specific proportions of the components depend on the raw materials and technology used

People have long been trying to use this type of natural fuel; medieval chronicles contain references to the fact that residents of the low-lying regions of what is now Germany a millennium ago received biogas from rotting vegetation by immersing leather furs in swamp slurry. In the dark Middle Ages and even the enlightened centuries, the most talented meteorists, who, thanks to a specially selected diet, were able to release and ignite abundant methane flatus in time, aroused the constant delight of the public at cheerful fair performances. Industrial biogas plants began to be built with varying degrees of success in the mid-19th century. In the USSR in the 80s of the last century, a state program for the development of the industry was adopted, but not implemented, although a dozen production facilities were launched. Abroad, the technology for producing biogas is being improved and is being promoted relatively actively; the total number of operating installations is in the tens of thousands. In developed countries (EEC, USA, Canada, Australia) these are highly automated large complexes, in developing countries (China, India) - semi-handicraft biogas plants for homes and small farms.

Percentage of the number of biogas plants in the European Union. It is clearly visible that the technology is actively developing only in Germany, the reason is solid government subsidies and tax incentives

What uses does biogas have?

It is clear that it is used as fuel, since it burns. Heating of industrial and residential buildings, electricity generation, cooking. However, not everything is as simple as they show in the videos scattered on YouTube. Biogas must burn stably in heat-generating installations. To do this, its gas environment parameters must be brought to fairly stringent standards. The methane content must be at least 65% (optimum 90-95%), hydrogen must be absent, water vapor has been removed, carbon dioxide has been removed, the remaining components are inert to high temperatures.

It is impossible to use biogas of “animal dung” origin, not freed from foul-smelling impurities, in residential buildings.

The normalized pressure is 12.5 bar; if the value is less than 8-10 bar, the automation in modern models of heating equipment and kitchen equipment stops the gas supply. It is very important that the characteristics of the gas entering the heat generator are stable. If the pressure jumps beyond normal limits, the valve will operate and you will have to turn it back on manually. It’s bad if you use outdated gas appliances that are not equipped with a gas control system. At best, the boiler burner may fail. The worst case scenario is that the gas will go out, but its supply will not stop. And this is already fraught with tragedy. Let us summarize what has been said: the characteristics of biogas must be brought to the required parameters, and safety precautions must be strictly observed. Simplified technological chain for biogas production. An important stage is separation and gas separation

What raw materials are used to produce biogas

Plant and animal raw materials

Plant raw materials are excellent for the production of biogas: from fresh grass you can get the maximum fuel yield - up to 250 m3 per ton of raw material, methane content up to 70%. Somewhat less, up to 220 m3 can be obtained from corn silage, up to 180 m3 from beet tops. Any green plants are suitable, algae and hay are good (100 m3 per ton), but it makes sense to use valuable feed for fuel only if there is a clear excess of it. The yield of methane from the pulp formed during the production of juices, oils and biodiesel is low, but the material is also free. The lack of plant raw materials is a long production cycle, 1.5-2 months. It is possible to obtain biogas from cellulose and other slowly decomposing plant waste, but the efficiency is extremely low, little methane is produced, and the production cycle is very long. In conclusion, we say that plant raw materials must be finely chopped.
Raw materials of animal origin: traditional horns and hooves, waste from dairies, slaughterhouses and processing plants are also suitable and also in crushed form. The richest “ore” is animal fats; the yield of high-quality biogas with a methane concentration of up to 87% reaches 1500 m3 per ton. However, animal raw materials are in short supply and, as a rule, other uses are found for them.

Flammable gas from excrement

Manure is cheap and is available in abundance on many farms, but the yield and quality of biogas is significantly lower than from other types. Cow pats and horse apples can be used in their pure form, fermentation begins immediately, biogas yield is 60 m2 per ton of raw material with a low methane content (up to 60%). The production cycle is short, 10-15 days. Pig manure and chicken droppings are toxic - so that beneficial bacteria can develop, it is mixed with plant waste and silage. A big problem is represented by detergent compositions and surfactants, which are used when cleaning livestock buildings. Together with antibiotics, which enter manure in large quantities, they inhibit the bacterial environment and inhibit the formation of methane. It is completely impossible not to use disinfectants, and agricultural enterprises that have invested in the production of gas from manure are forced to seek a compromise between hygiene and control over animal disease, on the one hand, and maintaining the productivity of bioreactors, on the other.
Human excrement, completely free, is also suitable. But using ordinary sewage is unprofitable, the concentration of feces is too low and the concentration of disinfectants and surfactants is high. Technologists claim that they could be used only if “products” only flow from the toilet into the sewer system, provided that the bowl is flushed with only one liter of water (standard 4/8 l). And without detergents, of course.

Additional requirements for raw materials

A serious problem faced by farms that have installed modern equipment for producing biogas is that the raw material should not contain solid inclusions; a stone, nut, piece of wire or board that accidentally gets into the mass will clog the pipeline and disable an expensive fecal pump or mixer. It must be said that the given data on the maximum gas yield from the raw material correspond to ideal laboratory conditions. To get closer to these figures in real production, a number of conditions must be met: maintain the required temperature, periodically stir finely ground raw materials, add additives that activate fermentation, etc. In a makeshift installation, assembled according to the recommendations of articles on “producing biogas with your own hands,” it is barely possible to achieve 20% of the maximum level, while high-tech installations allow you to achieve values of 60-95%.

Quite objective data on the maximum biogas yield for various types of raw materials

Biogas plant design

Is it profitable to produce biogas?

We have already mentioned that in developed countries large industrial installations are built, while in developing countries they mainly build small ones for small farms. Let's explain why this is so:

Does it make sense to produce biofuel at home?

Is it profitable to produce biofuel at home in small quantities on a private plot? If you have several metal barrels and other iron junk, as well as a lot of free time and you don’t know how to manage it - yes. But the savings, alas, are meager. And investing in high-tech equipment with small volumes of raw materials and methane production does not make sense under any circumstances.

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Without mixing the raw materials and activating the fermentation process, the methane yield will be no more than 20% of the possible one. This means that, in the best case, with 100 kg (hopper loading) of selected grass you can get 5 m3 of gas without taking into account compression. And it will be good if the methane content exceeds 50% and it is not a fact that it will burn in the heat generator. According to the author, raw materials are loaded daily, that is, his production cycle is one day. In fact, the required time is 60 days. The amount of biogas obtained by the inventor, contained in a 50-liter cylinder, which he managed to fill, in frosty weather for a heating boiler with a capacity of 15 kW (a residential building of about 150 m2) is enough for 2 minutes.

Those who are interested in the possibility of producing biogas are advised to carefully study the problem, especially from a financial point of view, and contact specialists with experience in such work with technical questions. Practical information obtained from those farms where bioenergy technologies have already been used for some time will be very valuable. published