Mas Bové Biogas Plant

A biogas plant is a facility that converts organic waste from the farms and feed mill at Mas Bové into useful resources. It works by reproducing, under controlled conditions, a process that already occurs in nature: anaerobic digestion. Inside a sealed, oxygen-free environment, microorganisms break down the organic matter contained in pig slurry, poultry litter and feed residues, transforming it into two products.

• Biogas: a methane-rich gas that can be burned as a fuel to produce renewable energy. At Mas Bové, it is used to generate thermal energy for heating. The Mas Bové plant produces 96,697 Nm³ of biogas per year.
• Digestate: the material remaining after digestion, which retains much of its nutrient content and is used as an organic fertiliser for agricultural land. The Mas Bové biogas plant recovers 3,816 m³ of water per year, which is reused for irrigation and cleaning.

Methane is a greenhouse gas that is released into the atmosphere when livestock manure accumulates in lagoons or storage tanks, especially when they are covered. The biogas plant uses these livestock effluents to generate methane under controlled conditions in a closed environment and burns it to produce energy. As a result, it helps reduce the environmental impact of the Mas Bové farms.

How do we use the resources generated?

The energy generated heats the sow farrowing unit and maintains the temperature of the anaerobic digester. As a result, renewable energy produced on the farm itself has replaced the propane gas that was previously used. The organic fertiliser obtained from the digestate is applied to the fields at Mas Bové, reducing manure management costs. The recovered water is used for both irrigation and the cleaning of the pig and poultry facilities.

What is biogas?

Biogas is a renewable energy source obtained through a biological process known as anaerobic digestion, which transforms organic matter (found in pig slurry, poultry litter and other organic waste) into a mixture of gases composed mainly of methane (CH₄) and carbon dioxide (CO₂), together with other trace gases.

What is a biogas plant?

A biogas plant is a facility designed to produce a renewable gas (biogas) from the treatment of organic waste through anaerobic digestion (in the absence of oxygen). This process makes it possible to generate energy (thermal or electrical) while also recovering water and fertiliser.

The IRTA Mas Bové plant is also a research and open-knowledge facility. In fact, it is the first biogas plant in Catalonia and in Spain to be managed by a public research institute while simultaneously providing a service to a working farm.

Foto xula general planta

A commitment to the valorisation of by-products

The project is part of IRTA’s commitment under one of the eight scientific strategic objectives of the 2024–2027 Strategic Plan: Promoting the bioeconomy through the valorisation of organic waste and agri-food by-products, a circular model that creates value from the sector’s biological resources beyond energy production.

This strategic objective focuses on reducing waste and making use of the waste that must inevitably be generated by turning it into a valuable resource and reintegrating it into the agri-food chain. This is the case for livestock manure and other residues, such as feed residues from the Mas Bové feed mill.

The bioeconomy, a circular economic model based on the use of renewable and local natural resources, is an essential tool for addressing today’s major food-system challenges, both global and local. These include mitigating climate change, improving soil health, and achieving more efficient water management.

Glossary of terms

• Co-digestion. The simultaneous digestion of two or more waste streams from different sources (in this plant: pig slurry, poultry litter, and feed residues). Mixing them balances the available nutrients and stabilises microbial activity, improving process performance and biogas production.
• Feed mixture. A homogeneous mixture of waste streams prepared in the feed tank and introduced into the digester. It is the raw material of the process.
• Pig slurry. A liquid mixture of pig manure and urine collected from the pits beneath the livestock buildings. It is the main feedstock used in the plant.
• Poultry litter. Excreta from poultry (hens and broilers) that is used as an input material for the digestion process.
• Anaerobic digestion (biomethanisation). A biological process that takes place in the absence of oxygen, in which microorganisms break down organic matter and convert it into biogas and digestate. It is the core process of the plant.
• Anaerobic. Occurring or living in the absence of oxygen. The opposite of aerobic (in the presence of oxygen).
• Bacteria and archaea. The microorganisms responsible for anaerobic digestion. Acting in sequence, they break down organic matter until methane is produced.
• Hydrolysis. The first stage of organic matter decomposition. Enzymes break down large and complex organic molecules (fats, proteins, and carbohydrates) into simpler molecules such as sugars, amino acids, fatty acids, and alcohols.
• Acidogenesis. The stage in which microorganisms convert these simple molecules into volatile fatty acids, alcohols, carbon dioxide (CO₂), and hydrogen (H₂).
• Acetogenesis. The stage in which alcohols, carbon dioxide, and hydrogen are converted into acetic acid, together with additional hydrogen and carbon dioxide. These compounds are the substrates required for methane production in the final stage.
• Methanogenesis. The process by which microorganisms called archaea convert acetic acid, carbon dioxide, and hydrogen into methane gas (CH₄), the component that gives biogas its energy value.
• Biogas. A mixture of gases produced during anaerobic digestion, consisting mainly of methane and carbon dioxide, with smaller amounts of ammonia, hydrogen sulfide, and hydrogen. It is a renewable energy source because it is produced from organic matter rather than fossil fuels, and the carbon dioxide released during combustion is considered biogenic, and therefore environmentally neutral.
• Methane (CH₄). The main component of biogas and the source of its energy value. It is also a potent greenhouse gas, which is why capturing and burning it prevents its release into the atmosphere.
• Carbon dioxide (CO₂). The second major component of biogas, with no fuel value.
• Hydrogen sulfide (H₂S). A corrosive gas present in small amounts in biogas. It must be removed before combustion to prevent damage to the equipment.
• Desulfurisation. The process of removing hydrogen sulfide from biogas. In this plant, it is carried out in the digester headspace by injecting small amounts of oxygen.
• Digestate. The material that remains after biogas has been extracted. It is rich in nutrients and is sent to the separator to produce fertiliser and recovered water.
• Fraction separation. The division of digestate, by means of mechanical pressing, into a solid fraction and a liquid fraction, each with a different end use.
• Solid fraction. The concentrated portion of the digestate that leaves the separator. It is sent to the manure storage area and used as a fertiliser.
• Liquid fraction. The clarified portion of the digestate that leaves the separator. It is stored in the covered lagoon before undergoing water recovery treatment.
• Filter press. A pressure-based separation unit equipped with screens of a defined mesh size (300–650 microns in this plant) that separates the digestate into solid and liquid fractions.
• Decantation (sedimentation). A gravity-driven process in which suspended solids settle to the bottom of a liquid. This occurs in the covered lagoon, where solids are separated by natural settling.
• Nitrification and denitrification. Biological processes that take place in the aerobic bioreactor, where nitrogen compounds are first oxidised and then converted into nitrogen gas (N₂), which is released harmlessly into the atmosphere. These processes occur within the treatment module, where clarified liquid is transformed into recovered water.
• Ultrafiltration. Fine filtration through tubular membranes that retain suspended particles and microorganisms.
• UV disinfection. The final treatment stage, in which ultraviolet light eliminates any remaining microorganisms and prepares the water for reuse.
• Recovered water. Treated water produced at the end of the treatment process, suitable for cleaning farm facilities and irrigating fields.
• Composting. The process in which the solid fraction of the digestate is mixed with other agricultural residues, such as pruning waste, and allowed to decompose until it becomes a mature and stable organic fertiliser.
• Organic fertiliser. A fertiliser derived from organic matter (in this case, digestate) that supplies nutrients to the soil and improves soil health, providing an alternative to synthetic inorganic fertilisers.
• Thermal energy. Energy in the form of heat. In this plant, the heat generated by the boiler maintains the digester at 38°C and heats the sow farrowing unit.
• Thermal capacity (kWt). The amount of heat that a system can generate per unit of time. This installation has a thermal capacity of approximately 100 kWt.
• Flare. A safety device that burns surplus or low-quality biogas, or biogas that must be removed during maintenance, preventing methane from being released into the atmosphere.
• Nm³ (normal cubic metre). A unit that measures a volume of gas under standard temperature and pressure conditions, allowing gas volumes to be compared consistently. Biogas production is measured in Nm³/year.
• Greenhouse gases (GHGs). Gases that trap heat in the atmosphere and contribute to climate change, such as methane, carbon dioxide, and nitrous oxide. The plant helps reduce GHG emissions by capturing and using methane from livestock waste.
• Circular economy. A model in which waste is recovered and returned to the production cycle as a resource rather than being discarded. The plant is an example of this approach, transforming livestock waste into energy, water, and fertiliser.
• Bioeconomy. A circular and sustainable economic model based on the use of renewable and locally available biological resources to produce goods and services. It is the strategic framework within which the IRTA plant operates.
• Valorisation. The process of converting a waste material or by-product into a useful resource within the same production chain.

This project has received funding under the incentive programme for grants supporting innovative biogas plant projects within Spain’s Recovery, Transformation and Resilience Plan.