Molins and the power of alternative fuels: driving circularity and decarbonization in the cement industry

Cement is a fundamental component of modern life, becoming the backbone of infrastructure, housing, and urban development worldwide. At the same time, industry is undergoing a significant transition. Producing clinker—the key component of cement—requires high energy inputs, which makes the sector particularly exposed to the global demand for lower-carbon solutions. The challenge lies in reducing emissions while keeping competitiveness, security of supply, and the affordability of construction materials.

For Molins this transition has become a catalyst for innovation. Over the last decade, we have built a robust portfolio of initiatives focused on using alternative fuels and repurposing raw materials to reduce its carbon footprint, cut reliance on fossil fuels, and advance circular economy practices. From industrial and commercial waste and end-of-life tyres (ELTs) to construction and demolition waste, we have demonstrated how materials once considered waste can become valuable resources for both energy and substitution of natural raw materials.  

This article explores the role of alternative fuels in our decarbonization strategy, focusing on three flagship initiatives: the Alternative Raw Materials (ARM) plant in Barcelona, the Pronatur RDF project near our Sant Vicenç dels Horts cement plant, and the End-of-Life Tyre recycling facility in Manresa.

The alternative raw materials plant: giving new life to waste 

One of the most emblematic initiatives in our circular economy strategy is the Alternative Raw Materials (ARM) plant, located in Pallejà, near Barcelona. Operational since late 2022, this facility illustrates how circular practices can be fully integrated into an industry as traditional as cement production. 

Since its launch, it has already processed more than 193,000 tons of waste from construction, demolition, and other industrial sources. In 2024 alone, the plant handled over 93,500 tons of material, representing a 25% increase compared to 2023. 

These volumes are more than statistics: they deliver a meaningful environmental benefit. By turning construction and demolition waste into CE-marked recycled aggregates and alternative raw materials suitable for use in cement manufacturing, the ARM plant avoided the emission of over 3,600 tons of CO₂ in 2024. Its proximity to our Sant Vicenç dels Horts cement plant further reduces transport-related emissions, reinforcing the environmental efficiency of the model. 

The facility is not an isolated case but part of a broader network. We operate eight waste valorization plants across Spain, managing a wide variety of materials such as steel slags, demolition residues, and end-of-life tyres. In total, these facilities valorized more than 345,000 tons of waste in 2024—a remarkable 52% increase year-on-year. Beyond diverting material from landfills, this network also prevents the extraction and long-distance transport of raw materials, significantly reducing associated CO₂ emissions. 

The ARM plant and its related facilities highlight our commitment to building a truly circular industrial model, one that prioritizes resource efficiency and material reuse. By reintegrating recovered materials into its own production processes, we not only lower our environmental footprint but also demonstrate how waste can be reimagined as a valuable input for sustainable construction. 

This approach is tightly linked with our broader decarbonization goals. Alongside material recovery, we are accelerating the substitution of fossil fuels with alternatives, many sourced from non-recoverable industrial waste. At the same time, it is incorporating renewable energy into its operations, both through supply agreements and on-site self-consumption facilities. Together, these actions are included within our Roadmap 2030, which sets a clear objective: a 20% reduction in Scope 1 and 2 CO₂ emissions by 2030. 

Pronatur and the rise of refuse-derived fuel 

While the ARM plant tackles materials, our Pronatur project addresses energy. Located in Montornès del Vallès, just 35 kilometers from our Sant Vicenç dels Horts cement plant, Pronatur has been operating since 2011 as a vertically integrated facility for producing refuse-derived fuel (RDF)—known in Spain as combustible sólido recuperado (CSR). 

Pronatur converts non-hazardous waste —paper, cardboard, plastics (non-PVC), textiles, wood, and rubber— into a high-calorific-value fuel that substitutes for petroleum coke (petcoke) in the clinker kiln. Over its lifetime, the plant has already recovered more than 680,000 tons of waste that would otherwise have gone to landfills. 

The environmental benefits are twofold. First, RDF displaces fossil fuels, significantly cutting CO₂ emissions per ton of cement produced. Second, it provides a local solution to the waste management problem by diverting thousands of tons of material from landfills each year. 

Pronatur’s operation is highly technical. Waste is shredded, metals are removed magnetically, and materials are screened by size and density. Near-infrared (NIR) optical technology removes PVC plastics, and an online analyzer continuously monitors calorific value, chlorine, and moisture content to ensure a consistent fuel stream.  

The facility’s integration with our cement plant creates a just-in-time supply model that minimizes storage and maximizes efficiency. Continuous operation ensures a continuous, year-round alternative fuel supply, strengthening the resilience of our energy system while reducing dependency on imported fossil fuels. 

End-of-Life tyres: from waste to energy and urban surfaces 

Another pillar of our alternative fuels strategy is the recycling of end-of-life tyres (ELTs). Spain produces approximately 300,000 tons of ELTs annually, a major environmental concern if not properly managed. Our response is its Granulated Rubber Project (GRP) plant in Manresa, established in 2016. 

The facility combines cutting-edge crushing, screening, and separation technologies to process tyres into several valuable outputs: 

• Chips destined for energy recovery, optimized for combustion in cement kilns. 

• Granulated rubber for use in sports fields, playgrounds, bike lane separators, and other urban furniture. 

• Recovered steel and textile fibers, which are separated and recycled through appropriate channels. 

Over nine years, the plant has processed more than 20 million tyres, making it a key player in Spain’s ELT recycling ecosystem. In energy terms, tyre-derived fuel (TDF) has become an important contributor to our decarbonization pathway. At Sant Vicenç dels Horts cement plant, more than 55% of fuel demand is now met by alternative sources, including ELTs. 

This dual focus on both energy and material valorization makes the GRP plant an exemplary circular economy project. On one hand, it reduces landfill dependency and the environmental hazards associated with abandoned tyres. On the other, it creates new materials for construction and urban development, reinforcing Molins’ brand identity as a sustainability-driven innovator. 

A replicable model for the industry 

The cement industry is often portrayed as a “hard-to-abate” sector. Yet our initiatives prove that with the right mix of technological innovation, circular economy practices, and strategic investment, meaningful decarbonization is possible. 

From recovering 193,000 tons of construction waste in just two years, to processing 20 million tyres, to generating refuse-derived fuel that displaces imported petcoke, we are demonstrating a replicable model. Its projects align environmental necessity with business competitiveness, showcasing how sustainability can be embedded across the value chain. 

As cities grow and the demand for construction materials continues, the importance of reducing the environmental footprint of cement will only intensify. Our commitment to alternative fuels not only addresses this challenge head-on but also positions the company as a benchmark in the circular, resilient, and low-carbon construction sector. 

Published in World Cement