The stages of building a biogas plant: what do businesses need to know?

The construction of a biogas plant takes an average of 18–24 months — this is the time required to progress from the initial consultation to the full-scale commissioning of the facility under a standard scenario. It is a complex engineering process comprising seven consecutive stages — from the feasibility study to commissioning.

The longest stage is obtaining the necessary permits (6–9 months). The most expensive stage is the purchase of equipment and construction and installation work (together accounting for up to 85% of the budget).

At the same time, the actual construction timescales for biogas plants and the final budget rarely stay within the initial parameters. The main reason is mistakes made at the start of the project. An inaccurate assessment of raw materials, a poorly considered site choice, or the lack of a contingency budget can extend the project timeline by months and add 10–20% to the cost.

This article is a practical guide for farm owners, agricultural businesses, and investors interested in building a biogas plant. We have compiled real-world construction timelines, common pitfalls, and a breakdown of costs — without any vague generalisations.

Timelines and stages of BGS construction: an overview

Building a biogas plant involves seven sequential steps, from the initial idea to reaching design capacity. Following this process minimises the risk of delays and cost overruns. Below is an overview of the entire project, including timelines.

Total project duration: 18–24 months. Carrying out certain stages in parallel (for example, procuring and manufacturing equipment whilst permits are being obtained) enables a reduction in duration to 14–18 months.

For projects involving the construction of a biomethane plant, the timeframe may be longer due to additional stages of integration into the gas network and the lengthy manufacturing process for ancillary equipment. In such cases, the construction timeframe for biomethane plants is often extended by 2–4 months.

Stage 1. Preliminary analysis and feasibility study

A feasibility study is the cornerstone of any project. Without it, it is impossible to accurately determine the plant’s capacity, select the appropriate technology, or calculate the payback period. Skipping this step is like building in the dark.

At this stage, biogas production is still being assessed on paper: how much raw material is available, how it should be used, and what the project’s actual economic viability will be.

What is being analysed:

• Raw material supply: types of waste (manure, litter, silage, pulp), daily quantity, consistency throughout the year, and delivery logistics.
• Energy balance: the intended use of the electricity and heat generated for own consumption or for sale to the grid; whether it is technically possible to connect to the grid.
• Site selection: sanitary protection zone (350–1,000 m from residential areas), distance to utility networks, logistics for raw material delivery.
• Financial model: CAPEX, OPEX, payback period, IRR — for a specific project.

For biogas plants on cattle farms, the minimum threshold for an economically viable project is 1,000–1,500 head of cattle or the equivalent in terms of biogas yield.

The feasibility study is carried out by an EPC contractor or a specialist consultancy firm. Duration: 1–2 months.

Stage 2. Design: Phase P or RP

Design involves developing a detailed technical solution tailored to a specific site. The project duration is 2–4 months. A high-quality design helps to prevent most errors during construction and reduces the risk of work stoppages.

What is included in the project:

• BGS process flow diagram — types and number of fermenters, gas holder, treatment system;
• a master plan of the project showing the detailed layout of all necessary structures and utilities;
• architectural and structural elements — foundations, buildings, sites;
• utilities — gas mains, pipelines, electricity;
• automation and security system;
• construction plan and cost estimate.

In some cases, it may be necessary to undergo an Environmental Impact Assessment (EIA) in order to obtain planning permission.

Common mistakes during the design phase:

• Underestimating the volume of feedstock — if a digester is designed for 100 tonnes per day but the actual feedstock input is 60 tonnes, biogas production may be 40% lower than planned (according to data from IEA Bioenergy and the European Biogas Association).
• Re-evaluation of biogas yield — if it is possible to assess the biogas potential in a laboratory, do so; however, bear in mind that laboratory figures are usually slightly higher than those obtained in practice, so a reduction factor of 0.85–0.9 should be applied.
• Insufficient space for digestate storage — usually, there is either no space left on the site for a lagoon, or there is a desire to sink it deeper; however, this is not possible during construction, and the dimensions are reduced (for example, geological surveys carried out during the dry season failed to take into account the possibility of higher groundwater levels in spring). 

The design phase concludes with the review of the design documentation — without this, a building permit cannot be obtained. The implementation period is an additional 1–2 months.

Stage 3. Obtaining planning permission for the biogas plant

This is the longest and most complex stage, taking between 6 and 9 months under standard conditions. Preparing documents in parallel shortens the timeframe, but requires experience and knowledge of the regulatory framework.

Plot of land

• Documents proving ownership or a long-term lease (for a minimum of 25 years).
• Changing the designated use of a plot of land — if the land is agricultural, this involves a separate procedure taking 2–4 months.
• Allocation of a plot of land for construction.

Urban planning documentation

• Planning conditions and restrictions (PCR) — obtained from the local planning authority. Processing time: 10–15 working days.
• Detailed site plan — required if no planning has previously been carried out on the site. Development timeframe: 3–6 months.

Environmental permits

An Environmental Impact Assessment (EIA) is mandatory for facilities processing more than 100 tonnes of animal-derived organic matter per day. The procedure typically takes 6–9 months on average, but may take up to 12 months, taking into account public consultations.

• The EIA report contains information on the impact of the proposed biogas plant on air quality, water, soil, flora and fauna, social impacts, and so on.
• Mandatory public consultations are being held — disregarding the views of the local community will scupper the project.

A permit for the discharge of pollutants (IDD) is obtained separately from the EIA procedure.

Technical Specifications (TS)

• Technical specifications for connection to the electricity grid: for the supply of electricity or parallel operation with the grid. Processing time: standard — 30 days; during martial law — 2–5 days.
• Technical specifications for connection to gas networks: where the injection of biomethane or the supply of fuel to the CHP from the network is planned.
• Technical specifications for water supply and drainage: where necessary, depending on the process flow diagram and the availability of on-site wells.

Simplifications during the period of martial law

Temporary simplifications were introduced by CMU Resolutions No. 1320 and No. 547, as well as NEURC Resolutions No. 875 and No. 832 of 2024. Now is the ideal time to launch the BGS construction project.

• In certain cases, simplified procedures apply to urban planning documentation.
• Shorter processing times for technical specifications — up to 5 days instead of a month.
• Design and construction in parallel — rather than sequentially.

It is important to note that a return to standard procedures is expected once martial law has been lifted.

Stage 4. Procurement of equipment for the BGS

The cost of equipment accounts for 40–50% of the total project budget. Lead time from order to delivery: 7–12 months for European equipment. This stage can be combined with the process of obtaining permits to save time.

Raw material preparation and feeding system

The quality of feedstock preparation for a biogas plant directly determines biogas yield. Poorly prepared feedstock reduces reactor productivity by 15–20%. Equipment required:

• Receiving tanks for liquid raw materials, fitted with agitators and heating systems.
• Shredders for solid materials — for silage, solid manure, litter and food waste.
• Pumps and dosing systems — for a consistent supply of substrate.

Biogas tank and biogas storage system

• A membrane roof on a digester — biogas collection and buffer storage.
• A separate gas storage tank — for stations with uneven consumption or cogeneration during peak hours.
• A desulphurisation and drying system is required prior to feeding gas into the CHP or upgrading plant.

A combined heat and power plant or a biogas boiler

• CHP: for the simultaneous generation of electricity and heat. Efficiency reaches 85–92%. The optimal choice for most projects.
• Biogas boiler: if the heat supplied by the district heating system is insufficient in winter, or if there is no district heating system — for the production of heat only.
• Upgrading equipment: depending on capacity, membrane modules or amine technology — for upgrading biogas to biomethane (95–98% CH₄).

Automation and control system

• temperature, pH, level and pressure sensors — continuous monitoring of fermenters;
• SCADA system — real-time parameter visualisation, alarm system;
• remote control — the ability to operate the station without the operator being physically present at all times.

Pro-Energy uses equipment from a trusted European manufacturer — HoSt Bioenergy Systems. This ensures reliability and access to after-sales support.

Stage 5. Construction and installation works

Construction and installation work takes 6–10 months and is the most resource-intensive phase. 25–35% of the total budget is allocated to the construction of fermenters and the installation of equipment.

Preparatory and groundworks

• Clearing and levelling the site, erecting fencing.
• Construction of access roads for heavy machinery.
• Excavations for tanks, trenches for pipelines and electrical cables, and foundations for equipment.

Construction of fermenters and installation of equipment

• Installation of tanks — steel or reinforced concrete with an anti-corrosion coating.
• Installation of substrate mixing and heating systems.
• Thermal insulation of the fermenters is essential for maintaining a temperature of 38–42°C in winter.
• Installation of the CHP, gas tank, and raw material preparation and supply system.

Utility installation and ancillary structures

• Gas pipelines from the fermenters to the CHP or the upgrading facility.
• Pipes for the heating and recirculation systems.
• Cable routes, switchboards, earthing and lightning protection systems.
• Staff room, laboratory, and digestate storage area.

Common problems during construction:

• Delays in equipment delivery: there may be delays due to customs clearance or hold-ups at the border. Please allow for a buffer of 3–4 weeks.
• Winter weather conditions: concrete works carried out at temperatures below +5°C require the mixture to be heated — this adds 15–20% to the cost, so we recommend pouring concrete structures during the warmer months.

Stage 6. Commissioning work

Commissioning of the BGS — 1–2 months of work by the equipment supplier’s engineers and the plant’s own staff. The quality of this stage determines whether the plant will reach design capacity on schedule.

Cold start — testing systems without raw materials

• Checking the gas pipes and gas tank for leaks.
• Testing of pumps, mixers and feed systems.
• Automation settings: alarm systems, emergency shut-off valves, SCADA.
• Checking the connection of the CHP to the mains and synchronisation.

Hot start — working with water and inoculum

• Filling the fermenters with water — checking the heating system and the uniformity of heating.
• Testing the operation of mixers and pumps under load.
• Introduction of inoculum — digestate from another biogas plant to initiate methane fermentation, or cattle manure that has been aged under specific conditions.

Staff training

A biogas plant is a dynamic biotechnological facility. Staff must understand the biochemistry of the methane fermentation process. Without this understanding, operators react to deviations too late, resulting in a loss of productivity.

• Procedure for feeding raw materials and monitoring the ratio of components.
• Monitoring of key parameters: temperature, pH, FOS/TAC, and methane concentration.
• Action to be taken in the event of emergencies — gas leaks, power cuts, or fermentation tank acidification.

Stage 7. Commissioning

Commissioning is the final step before the commercial launch. Duration: 1–2 months. At this stage, the plant gradually reaches its design capacity rather than starting up at 100% immediately.

1. The reactors should be filled with inoculum to 25–30% of the tank’s capacity.
2. Gradual introduction of raw materials — over a period of 4–6 weeks, the load is increased from 20% to 100% of the design capacity.
3. Monitoring of parameters — daily checks of pH (6.8–7.2), temperature (38–42°C), and biogas composition.
4. It takes between 6 and 12 weeks to reach the design capacity for biogas production, depending on the quality of the inoculum and the feedstock.

Final steps for commercial operation:

• Signing of the certificate of readiness for commissioning.
• Connection to the electricity and gas networks in accordance with the technical specifications.
• The conclusion of contracts for the supply of electricity or for feeding electricity into the grid.
• Obtaining an electricity generation licence from the NEURC (if the capacity exceeds 1 MW or the sale of electricity is planned).
• Setting up a system for recording digestate and organising its disposal or sale.

Examples of Pro-Energy projects confirm that, provided the plant is commissioned correctly, it achieves 95%+ of its design capacity within the first month of stable operation.

BGS construction budget: breakdown of costs

The estimated construction cost of a biogas plant is from €2.5 million per 1 MW of installed capacity (according to data from the International Renewable Energy Agency (IRENA) and the European Biogas Association “Biogas and Biomethane in Europe“ report). For a 2–3 MW plant (a typical size for an agricultural holding), the total CAPEX is €5–9 million. Below is a breakdown of costs by item.

Never plan a budget without a contingency fund. 5–10% for unforeseen expenses is not an over-caution, but an industry standard. Projects without a contingency fund face construction delays or are forced to compromise on quality.

7 common mistakes made during the construction of a biogas plant

Most of the problems encountered during the construction of a biogas plant are the result of avoidable mistakes. Here are the seven most common ones, each of which has cost real-world projects time and money.

1. Underestimating the raw material supply. Check not only the volume of waste, but also seasonality, potential changes in livestock numbers, and competing consumers. Stock levels should be 20–30% above the estimated volume.
2. Incorrect capacity selection. Excess capacity means money tied up in idle equipment. Insufficient capacity means the station is operating under load. Optimal: 85–95% of design capacity.
3. Cost savings on design. The design of a biogas plant accounts for 3–5% of the budget. Clients who halve this budget end up spending ten times as much on rectifying errors during construction.
4. Ignoring public opinion. An EIA that fails to take the local community’s views into account could stall a project for years. Engage with the public before the procedure begins, not during it.
5. Lack of a budget contingency. Real-world experience shows that one in three projects exceeds the initial budget by 10–20%. Reasons include changes during construction, supply delays, and rising material costs.
6. Cost savings through automation. SCADA systems and sensors are essential. A plant without proper monitoring requires the constant presence of a qualified engineer. The cost of a SCADA system can often be recouped within the first six months of operation.
7. Lack of a plan for digestate disposal. Digestate is a valuable organic fertiliser. However, without legal status as a commodity and organised logistics, it becomes a problem. Plan for its disposal as early as the feasibility study stage if you do not have your own fields on which to apply the fertiliser.

Choosing the right EPC contractor — a company with a track record of completed projects, rather than just impressive presentations — helps to avoid most of these mistakes.

Conclusion: the key to the successful construction of the BGS

The construction of a biogas plant is an 18–24-month project comprising seven consecutive stages. The longest stage involves obtaining planning permission, whilst the most expensive involves the equipment and installation. The most critical phase for the project is the start: errors in the feasibility study and design can prove most costly.

Three key factors for success: high-quality preparation of the raw material base, an experienced EPC contractor, and a realistic budget with a 15–20% contingency. Now is the best time to launch: simplified permitting procedures, international support, and growing demand for biomethane in the EU.

Please contact the Pro-Energy team for advice. We offer turnkey construction of biogas plants — from feasibility studies and design to commissioning and maintenance. We will calculate the payback period for your business and assist you with all the necessary permits and approvals.

Frequently asked questions about the construction of the BGS

How long does it take to build a biogas plant?

From concept to launch — 18–24 months. The longest stage is obtaining permits (6–9 months, but this can take up to 12 months); the shortest is commissioning (1–2 months). Carrying out some steps in parallel makes it possible to reduce the timeframe to 14–18 months.

What are the main permits required for the construction of a BGS?

For a standard project, the following are required: urban planning conditions and restrictions, land title documents, an environmental impact assessment for facilities handling more than 100 tonnes of manure per day, technical specifications for connection to utilities, a project assessment, and a building permit. During the period of martial law, most of these procedures have been simplified.

How much does it cost to build a biogas plant?

Approximately €2.5–3 million per 1 MW of installed capacity. Breakdown: equipment — 40–50%, construction — 25–35%, design and permits — 5–9%, commissioning — 2–3%, contingency — 5–10%. The final figure depends on the type of feedstock, technology, and grid connection conditions.

What is the minimum capacity that is economically viable?

For livestock farms — from 1,000 kW (1,000–1,500 head of cattle + crop waste). The optimal range for a quick return on investment is 2–3 MW. Smaller projects are possible if several farms collaborate or if the raw materials are available free of charge.

References to the sources used in writing this article:

1. https://www.irena.org/
2. https://www.europeanbiogas.eu/
3. https://www.nerc.gov.ua/tag/postanovi?&type=all&tag=%D0%9F%D0%BE%D1%81%D1%82%D0%B0%D0%BD%D0%BE%D0%B2%D0%B8
4. https://www.ieabioenergy.com/