Turning Urban Waste into Value: European Cities Explore Biorefinery Innovation in Zaragoza

Zaragoza Biorefinery Visit by ICLEI Europe © Circular Biocarbon

From 24-25 June, cities from across Europe met in Zaragoza to experience the recently inaugurated flagship biorefinery built by Urbaser, the coordinator of the EU-funded project Circular Biocarbon. The biorefinery is demonstrating how the Organic Fraction of Municipal Solid Waste and sewage sludge can be transformed into high-added-value materials through advanced biorefinery technology.

Representatives from Warsaw (Poland), Bornholm (Denmark), and Mikkeli (Finland) joined the visit on-site, while participants from Seville (Spain) and Gipuzkoa (Spain) joined online for the workshops. The event marked the first in-person meeting of the Circular Biocarbon City Interest Group, bringing together cities exploring how to turn their waste streams into valuable resources that support circularity, innovation, and climate neutrality.

During the visit, participants learned that after just six months of operation, the facility is already refining biogas into ultra-pure methane and carbon dioxide, each with over 98% purity.

The programme included a visit to Urbaser’s biorefinery and its Alfonso Maíllo Innovation Center, where participants saw first-hand the facilities taking the first steps in producing value from waste — by breaking down organic waste into key components, mainly methane and carbon.

On the second day, participants observed a live demonstration of Zaragoza’s separate waste collection and street cleaning systems. They also heard from the REDOL project, which presented Zaragoza and Aragon’s broader ambition to become a hub for circularity. The day continued with workshops exploring the potential of rolling out high-tech biorefineries in more cities across Europe.

Participants especially emphasised the power of public procurement, the importance of local backing — both from communities and political leaders — and the need for sustainability benefits to go hand in hand with local job creation.

The Zaragoza visit is the first in a series of study visits, or in-person workshops, planned for the City Interest Group. It was organised by ICLEI Europe, with Urbaser and the City of Zaragoza each supporting the event by showcasing their efforts toward more circular waste management.

You can find pictures from the visit below or see them all on Flickr.