WELTEC BIOPOWER has embarked on an ambitious project to construct a biomethane plant in Colmenar Viejo, located north of Madrid, in partnership with environmental services provider PreZero and Enagás Renovable. The construction commenced in August 2026 and aims to generate up to 60 gigawatt-hours of renewable energy annually, sufficient to meet the energy needs of approximately 11,700 households, or around 30,000 residents.
Project Overview and Environmental Compliance
The biomethane facility has successfully secured all necessary urban planning and environmental permits for its construction. This includes planning approval and a construction licence from the municipality of Colmenar Viejo, as well as an Integrated Environmental Authorisation from the Community of Madrid. This authorisation confirms that the project adheres to stringent technical and environmental standards required for such facilities.
Key Players in the Project
The development of the plant is spearheaded by PreZero, a subsidiary of the Schwarz Group, which also owns Lidl and Kaufland. PreZero boasts extensive experience in waste management and the biomethane sector, managing waste for over twelve million people across Spain and Portugal. In 2025, the company was responsible for producing more than 53% of Spain’s biomethane.
Enagás Renovable, another key partner, is a prominent independent energy producer in Spain, focusing on renewable gases and decarbonisation initiatives. The company is actively involved in over 20 projects nationwide, positioning itself as a significant contributor to Spain’s energy transition.
Waste Processing and Energy Production
The new facility is designed to process up to 75,000 tonnes of organic waste each year. This waste will primarily consist of separately collected household biowaste from the brown bins in Colmenar Viejo and surrounding areas. Currently, organic material makes up about 40% of household waste by weight in the region. By converting this waste into renewable biomethane, the facility aims to reduce the volume of waste sent to landfills, which currently accounts for around 60% of the region’s waste disposal.
Innovative Plant Design
At the core of the Colmenar Viejo plant are three stainless-steel digesters, each measuring 25.34 metres in diameter and 10.05 metres in height, with a total volume of 5,067 cubic metres. This tall tank design allows for a high throughput of substrate while occupying a relatively small footprint, optimising the use of the approximately 6,200-square-metre site.
A gas-tight pre-storage tank with a capacity of 1,177 cubic metres is positioned upstream of the digestion process to ensure a consistent supply of substrate and stable operational conditions. The facility employs hygienisation processes to comply with legal requirements for treating organic waste streams.
All digesters and storage tanks are constructed from high-quality stainless steel, manufactured using WELTEC BIOPOWER’s modular construction system. This approach allows for industrial prefabrication and on-site assembly, ensuring high production quality and facilitating efficient logistics and scalability. According to Alain Priser, International Sales Manager at WELTEC BIOPOWER, stainless steel is particularly resistant to corrosion, which is crucial given the challenging biological and chemical conditions in the digestion process. This durability contributes to the plant’s longevity, operational reliability, and low maintenance needs.
Environmental and Community Impact
The facility is designed to operate as a closed and sealed industrial system, utilising advanced biofilters and activated carbon systems to eliminate up to 99% of odorous substances from exhaust air. The biomethane produced will be injected directly into the gas grid, negating the need for on-site storage.
With the establishment of the biomethane plant, both the municipality of Colmenar Viejo and the Community of Madrid are taking significant strides towards sustainable waste management and promoting a circular economy. The project aligns with the European Union’s goal of reducing municipal waste sent to landfills to no more than 10% by 2035.
Furthermore, the project is set to deliver tangible benefits to the local community. A social agreement with the municipality outlines various economic and community advantages, including energy support for local public schools, free treatment of residents’ separately collected organic waste, and priority job opportunities for local residents. An environmental education centre will also be established to enhance environmental awareness within the community.
Conclusion
By integrating WELTEC BIOPOWER’s advanced plant technology with PreZero’s waste management expertise and Enagás Renovable’s renewable gas knowledge, the Colmenar Viejo project creates a sustainable cycle: organic waste is transformed into renewable energy, landfill volumes are reduced, and approximately 30,000 residents will benefit from green energy each year. This innovative approach not only addresses waste management challenges but also contributes to the broader goals of energy sustainability and environmental protection.
For those interested in learning more about this pioneering plant, WELTEC BIOPOWER will showcase its technology at stand 276A during the Salon del Gas Renovable in Valladolid, taking place from 29 to 30 September 2026.
This article was submitted via the World of Renewables press desk.
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