The first plant to produce synthetic eco-aggregates from industrial waste

An aggregate is the granular material, such as gravel, sand, or crushed stone, that makes up most of the volume of concrete and other building materials. It is one of the most widely consumed materials in the world, and its extraction from quarries has a direct environmental impact. 

Eco-aggregates are synthetic aggregates manufactured using accelerated carbonation. It is lightweight, durable and easily compactable. It is certified according to the  UNE-EN 13055 standard, which regulates lightweight aggregates for concrete and mortar and ensures full compatibility with industry standards. 

Its applications include mortar, non-structural concrete, blocks, self-leveling, civil engineering, urban furniture, etc. It is a material that integrates seamlessly into existing construction processes, without requiring modifications to formulations or work methodologies. 

There are three broad categories of aggregate: 

• Natural aggregate is extracted directly from quarries and rivers. It has a positive carbon footprint and exerts pressure on land use. 
• Conventional recycled aggregate comes from construction and demolition waste (CDW): concrete, ceramics, and debris. It reduces pressure on quarries but its carbon footprint remains significant. 
• Synthetic eco-aggregate is a new category: it is produced through accelerated carbonation using industrial thermal wastes and captured CO₂. Its carbon footprint is negative, as the process absorbs more CO₂ than it emits. 

The key difference between the eco-aggregate and conventional recycled aggregate is not just its origin, but its process. While CDW recycling crushes and reuses existing materials, the eco-aggregate is manufactured from scratch using waste streams that would otherwise go to landfills, permanently sequestering CO₂ through mineralization in the process. 

Thermal wastes are among the most complex industrial waste streams to manage. They come from facilities with thermal processes, including municipal waste to energy plants. The residues left after incineration, bottom ash, and fly ash, have no clear industrial application nor can they be recycled through conventional means. The primary disposal method for this type of material can be found in the nearest landfill. 

At the same time, the construction sector is structurally dependent on natural aggregates, which are quarried in quantities that place growing pressure on land use and natural resources. Finding industrial alternatives to this extraction has been a challenge for decades. 

These two seemingly disconnected problems now converge within a single industrial process. What was once a dead-end waste stream is transformed into the raw material for a building material. What was once an unused emission becomes the agent that permanently sequesters the carbon within that material. 

There are two ways to address emissions. The first is to reduce them by upgrading processes or technology. The second, which is more demanding and less common on an industrial scale, is to permanently remove carbon from the atmosphere. The facility operates within the second category. 

The captured carbon is not stored transiently or reversibly. It remains permamently and stably mineralized within the eco-aggregate. This distinction is significant: the process is not merely emissions-free; it actively, verifiably, and permanently removes carbon. 

This process can be certified through Carbon Removal Credits on specialized international registries that adhere to rigorous standards of verification, traceability and permanence. Each credit represents one metric ton of CO₂ effectively removed from the atmosphere and permanently stored, in accordance with internationally recognized criteria. This allows companies and organizations to offset residual or hard-to-abate emissions. Carbon removal credits are an essential pillar in the global transition toward climate neutrality, contributing directly to a net reduction in atmospheric concentrations. Their development faces greater technological, economic and scalability barriers, resulting in a more limited supply and, therefore, greater strategic value. In this context, BEA generates them as an intrinsic co-product of its activity, positioning itself as a key player in an emerging market with high standards of quality and credibility. 

In the voluntary carbon market there are two types of credits: 

• Reduction credits: prevent emissions from occurring (energy efficiency, renewables). These are the most common. 
• Removal credits (Carbon Removal Credits): permanently remove CO₂ that has already been emitted into the atmosphere. They are scarce and carry greater strategic value. The eco-aggregate generates this second category. 

The Port of Bilbao is one of the leading industrial ports in northern Spain, home to an ecosystem of world-class energy and industrial companies. The plant is integrated into this ecosystem as part of a larger system, rather than an isolated project. 

Petronor brings to the project its extensive industrial experience, technological integration capacity and a commitment to the energy transition in the Basque region that ensures the project’s strategic continuity. 

The plant creates new specialized jobs in the fields of carbon capture technology and the circular economy, contributing to the industrial development of a region that has long promoted innovation as a driver of competitiveness. 

Furthermore, the project is not designed as a one-off, but rather as the first in a series. The vision is to scale this model to other facilities, positioning Bizkaia and the Basque Country as a European hub for carbon-capturing circular materials.

The challenges outlined at the beginning, unresolved waste, emissions, and aggregates extracted from quarries, today have a concrete answer in a specific location. 

Eco-aggregates are more than just a building material. It is proof that, through innovative technology it is possible to connect waste recovery, CO₂ capture and the production of sustainable construction materials.