Agricultural biogas plant: principle of operation, profitability, construction

Renewable energy sources become increasingly popular these days. The reason is simple – they are inexhaustible and environmentally friendly. In the agricultural sector, one can see a growing interest in biogas, which is a natural gas produced by the fermentation of biomass (organic matter). Biogas is a mixture of gas and methane. In this article, we will explain to you what an agricultural biogas plant is, what principle it operates on, and in what situations it is profitable to build an agricultural biogas plant.

What does an agricultural biogas plant consist of? How to plan an investment? What are the basic elements of an agricultural biogas plant construction? See it yourself!

Agricultural biogas plant in Poland

Pro-climate trends, which are the aftermath of recognising the effects of overexploiting non-renewable energy sources, make today’s market increasingly bold in looking toward greener solutions such as biogas plants. Biogas is a fuel that is widely used by European countries. Compared to them, Poland still fares quite modestly, but there are many indications that this may change soon, as the construction of biogas plants occupies an important place in the Orlen Group’s investment strategy – by 2030, Orlen plans to produce over 1 billion cubic meters of biogas per year.

Due to the high share of agricultural land and forests in the country’s area, Poland’s potential for biogas market development is very high. This translates positively into biomass harvesting opportunities. It is worth mentioning that the proper use of biogas will enable Poland to become more energy-independent while increasing our country’s security.

Agricultural biogas plant: principle of operation

A home agricultural biogas plant is a solution for farm owners who are looking for an effective way to manage waste from agri-food production. The definition of an agricultural biogas plant is simple – this term is used to describe a plant that produces biogas from biomass, i.e., in the case of farms, from straw, livestock manure, beet leaves, etc. In other words, the operational principle of biogas plants is based on the use of natural processes that result in the production of the necessary electricity and heat. In agricultural operations, a biogas plant has an additional advantage – it allows to get rid of by-products. The whole process works based on power generators. They constitute a so-called cogeneration system and are powered precisely by organic biogas.

How does an agricultural biogas plant work? Despite appearances, the operation of an agricultural biogas plant is not complicated.

• A special tank is first used to grind the supplied substrate.
• Anaerobic digestion then takes place in the digester. It should be added that the design of the chamber depends on the raw material used by the biogas plant.
• From the digester, the produced biogas is transported to a storage facility. It should be noted that before the biogas is used in the unit, it is necessary to properly dry it and clean it of hydrogen sulphide.
• From the storage facility, the biogas is pumped to a cogeneration unit. The calorific value of biogas depends on the substrates used in the production process.

The operational principle of an agricultural biogas plant is therefore relatively simple. The resulting biogas allows the generation of heat and electricity, and the operation of biogas plants is regulated by law. Biogas plants are safe for the surroundings and nearby residents. If you want to know more about biogas plants, discover what is a container biogas plant, what a near-house biogas plant should look like and how to get the necessary subsidy for a biogas plant. If you find that such a solution will support the operation of your farm, you can find the necessary information in the linked articles on our blog.

What is the cost of an agricultural biogas plant?

The cost of building an agricultural biogas plant is one of the primary issues for future investors. How much you ultimately have to pay for the installation of an agricultural biogas plant depends primarily on its capacity.

• For large farms, installations of 0.5 MW and above are optimal.
• Smaller crops or farms can invest in a biogas plant with a capacity of about 10 kWe.
• A small-scale agricultural biogas plant is an investment that takes longer to pay off, but it can still be very profitable if the farm has enough access to the substrate needed for biogas production. In practice, the cost of a small agricultural biogas plant can be several hundred thousand PLN.

Read also what the construction of a biogas plant looks like and estimate the preliminary costs of the project A SWOT analysis of the agricultural biogas plant, in which you analyse the strengths (S) and weaknesses (W), opportunities (O) and threats (T) of the agricultural biogas plant, is crucial in making a decision – this way you can organise the information more easily.

Agricultural biogas plant: profitability

When analysing the price of an agricultural biogas plant, you need to consider the benefits you can count on if you decide to make a similar investment.

• A near-house agricultural biogas plant allows you to significantly minimise electricity bills. This is important, especially for those households where electricity consumption is very high due to their business profile.
• The digestate – the residue from biogas production – can be used as fertiliser.  It features by high nutrient content, beneficial for soil fertilisation.

The profitability of an agricultural biogas plant is largely dependent not only on the amount of substrate obtained in the operation of the farm but also on its type – all these factors you must take into account when planning your investment. Calculations for an agricultural biogas plant are best outsourced to specialists, who will be able to assess whether, in the case of your farm, such a solution will produce a satisfactory return on investment.

Construction of an agricultural biogas plant

The scheme of an agricultural biogas plant is relatively simple. As we mentioned above, the basic components of an agricultural biogas plant are the pre-tank, the digester tank, the biogas storage and the cogeneration unit.

• Planning an agricultural biogas plant step by step, before you make any decisions, you need to consider what amount of substrate your farm has at its disposal– on this basis, you will assess whether you can afford a large investment, or whether only a mini agricultural biogas plant is possible.
• When preparing a project to build an agricultural biogas plant determine what budget you have. Usually, the investor has to cover most of the expenses out of their own pocket, but some can be subsidised with loans or support programmes.

Agricultural biogas plant: project

The Ministry of Agriculture and Rural Development has estimated the potential for biogas energy production at more than 7 million cubic meters – this potential is still untapped. Therefore, the Ministry has prepared a draft act on facilitating investments in agricultural biogas plants. The design and construction of biogas plants are handled by specialised companies that offer overall management of the investment process. Eneria’s offer includes special biogas power generators.

Location of agricultural biogas plant

When choosing a site for the construction of a biogas plant, you must consider determining the optimal distance from buildings, which is established by law. Already at this stage, consider whether the biogas plant will be expanded in the future – so you can choose a location that will allow you to extend your business without problems. Not only must the tanks for animal excrement and digestate be properly located, but also the tank in which biogas will be stored. This type of tank must not be built at a distance of less than 20 meters from premises where people are to stay, investor buildings and other rooms not connected with the biogas plant.

What do you need to remember? An agricultural biogas plant allows us not only to reduce electricity bills but also to manage agricultural production waste and obtain digestate that can be used as fertiliser. Therefore, if only for the reasons mentioned above, it is worth exploiting the potential of biomass and considering installing a biogas plant based on CAT’s gas engine technology.

More about our biogas plant implementations.

Wrtten by: Paweł Kwasowiec
CHP Sales Manager & Expret