Biogas plants for slurry management


An increasing volume of slurry is generated, and the legislation is increasingly restrictive

One problem facing the livestock sector is what to do with the effluents. To comply with the new legislation that prevents the application of slurry directly to the field, we must use processes that have increased management costs.


The generation of electrical and thermal energy with slurry management

We have the technology and experience to respond to the needs of an increasingly regulated and competitive sector. Customised, scaled and modular biogas plants for self-consumption.

Is it profitable for me to manage slurry with a biogas plant on my farm?

These are the minimum requirements for the installation of a biogas plant:

  • Sows, the number of head of swine must be greater than 2,500 – 3,000.
  • Milking cattle, the number of head of cattle must be greater than 300.
  • Fodder pigs, if there is no energy consumption, the project will not be profitable.

    The problem: What to do with the slurry?

    Livestock faces the challenge of what to do with its effluents, adapting its industry to the current legislation (within a more restrictive European framework than the one in Spain).

    The slurry, whatever its origin (porcine, bovine, ovine, goat, avian), in its composition, presents an organic load that, by law, prevents its discharge into the watercourse or direct application to the field. One option is the implementation of a treatment plant for its treatment, but its high cost (approximately 1 million euros) prevents access to this technology.

    prohibido esparcir purín en plato, abanico ni cañon

    Changes in the regulations on farm slurry and effluents 

    Royal Decree 980/2017, which modifies the 2014 Royal Decrees (1075/2014, 1076/2014, 1077/2014, and 1078/2014), applies a new regulation for the distribution of slurry and effluents from livestock farms . This tightening of the regulations strongly affects the livestock sector, a sector that already had problems managing the large amounts of slurry generated, above all, by pigs, which generate the greatest amount of liquid waste.


    Royal Decree 980/2017 extract

    “The application of slurry to agricultural surfaces may not be carried out by means of splash-plate, fan, or gun systems…” “solid manures must be buried after application…”

    This means that splash-plate, fan, or gun systems may no longer be used to spray slurry to avoid atmospheric contamination. This legislation aims to stop the use tanks to eliminate slurry.

    Non-compliance with the new regulations will result in exclusion from CAP (common agricultural policy) subsidies and aid.

    Solution: slurry management and energy generation with a biogas plant

    The production of biogas with waste from any livestock activity (pig, cow, sheep, goat, chickens) is the solution for the treatment and sustainable management of liquid manure, adapting to current regulations and the foreseeable more restrictive legislation, which is coming as a consequence of the transposition of community laws.

    With the generation of biogas, the environmental impact of farming operations on the area in which they are established is reduced, improving their social acceptance.

    Planta de Biogás estiércol vacuno
    Planta de Biogás estiércol vacuno

    Advantages of a biogas plant, explained point by point

    Energy autonomy, consumers without a connection point to the grid will have a power supply thanks to the energy generated with their own resources, which will result in a real improvement in the use of renewable sources. Generation of thermal energy (heat) with multiple possible uses on the farm. From the cooling of milk in a dairy farm to the supply of domestic hot water.

    Decrease in the volume of the effluent, and reduction of the management costs of the liquid digest

    In the biological process of biogas generation, the organic load of the slurry is reduced, and with this, the legally applicable cubic meters per hectare increase. More quantity can be applied to the plots near where the slurry is generated, saving fuel and man-hours.

    To lower the costs of application to the field, the volume must be reduced. Therefore, by using the thermal energy generated by the biogas plant, we can concentrate the digest by evaporation, making it richer in nutrients, and with a lower transport cost (per fertiliser unit).

    During the time that the slurry is in the biogas plant, it is subjected to “anaerobic composting” that eliminates a high percentage of the pathogens, seeds and other undesirable components in the slurry prior to its fermentation.

    A solid composted by-product with stabilised nutrients (C, N, P, S, K)  is obtained, increasing its agronomic value. We obtain a liquid that (previously certified before administration) starts as mere slurry and is transformed into a fertiliser capable of being classified as organic.

    Drastic odour elimination, as the effluent is practically odorless. The greenhouse effect that is attributed to farms due to manure is eliminated, since there are no methane emissions, as it is immediately added to the digester, prior to the emission of methane, preventing the loss of its methanogenic potential . This also avoids conflicts with third parties due to bad odours.

    balsa de recepción de purines encon agitador planta de biogás
    Planta de Biogás estiércol vacuno

    SmallBiogas, integral technology for waste recovery that adapts to livestock farms

    SmallBiogas is a customised, scaled and modular biogas plant technology for self-consumption. It adapts to the productive processes of the cattle farm.

    We have the technology and experience to respond to the needs of an increasingly regulated and competitive sector.

    We propose a circular economy scheme, which improves the economic feasibility of your industry.

    Energy self-consumption in Spain and the trends in Europe

    Due to the transposition of community directives, improvements that favor self-consumption are slowly being incorporated in Spain.

    As we have already seen with Royal Decree Law 15/2018 of 5 October on energy transition, the so-called “sun tax” that penalised self-consumption has been repealed. This repeal of the “sun tax” provides a boost for the installation of biogas plants in our country.

    Practical example

    The cost of applying the slurry in the field is between 2 and 3 euros/cubic meter, therefore, applied to a practical example, we would have:

    If a farm generates 150 cubic meters/day at a cost of 11,250 euros/month, by reducing its discharge volume, with the application of thermal energy, to 100 m3/d, the cost would be 7,500 euros/month, which represents a savings of 3750 euros/month.