Economía Circular en el Contexto Urbano

The circular economy in the urban context begins with an analysis of city metabolism, which quantifies the flows of materials, energy and waste that enter, circulate through and leave the urban system. According to the Circularity Gap Report 2023 by Circle Economy, cities consume 75% of the world's natural resources, generate 50% of global waste and emit 70% of CO₂ emissions, despite occupying just 3% of the Earth's land surface. The urban metabolism study of Brussels, carried out by the Vrije Universiteit Brussel (2021), revealed that the city imports 13.6 million tonnes of materials annually and exports 4.8 million as waste, with a circularity rate of just 7.2%.

The transition to a circular model requires closing material loops at neighbourhood, district and metropolitan scale. The Ellen MacArthur Foundation estimates that applying circular economy principles to five key urban sectors — construction, food, mobility, textiles and electronics — could reduce European city CO₂ emissions by 40% by 2050 and generate an additional economic value of 1.8 trillion euros annually. At EU level, the European Commission projects that the circular economy will create 700,000 new jobs by 2030 and reduce raw material consumption by 32%, according to its Circular Economy Action Plan (2020). Cities such as Amsterdam, Paris and Ljubljana have adopted circularity strategies with quantified targets and defined timelines.

Waste management is the most visible pillar of the urban circular economy. Ljubljana, the first European capital to adopt a zero waste goal in 2014, increased its recycling rate from 29% in 2008 to 68% in 2022, cutting waste sent to landfill by 59%. The system is based on separate collection of 7 fractions (organic, paper, glass, packaging, textiles, electronics, residual) at frequencies adapted to the waste type, complemented by 2 reuse centres that recover 1,200 tonnes annually of items in good condition. The cost of the service has remained stable at 60 euros/inhabitant/year, below the European average of 85 euros.

The organic fraction offers the greatest circular potential in cities. Milan introduced mandatory biowaste collection across the city's 1.4 million households in 2014, achieving a capture rate of 95% of the organic fraction. The material is converted into certified compost and biomethane at two plants with a processing capacity of 150,000 tonnes per year. The biomethane produced — 8.5 million m³/year — fuels a fleet of 1,400 municipal buses, closing a loop that turns kitchen waste into public transport fuel. The ISWA (International Solid Waste Association) rates the Milan model as a world reference, with a treatment cost of 92 euros/tonne, lower than the 120-180 euros/tonne for controlled landfilling in northern Italy.

The construction sector represents the largest material flow in urban metabolism: in the EU it generates 374 million tonnes of waste annually, 36% of the total. The circular economy applied to construction operates at three levels: building reuse (adapting existing structures), component reuse (beams, windows, sanitary ware) and material recycling (concrete, steel, timber). The city of Amsterdam, through its Circular Strategy 2020-2025, requires all public construction projects to incorporate a minimum of 20% recycled or reused materials, and that new buildings be designed for 90% disassembly of their components at end of life.

Urban industrial symbiosis connects the waste from one activity with the inputs of another within the same city. The eco-industrial park at Kalundborg (Denmark), operational since 1972, is the pioneering model: waste from the Orsted power plant (steam, ash, gypsum) feeds a Gyproc plasterboard factory, an Equinor refinery and an aquaculture farm, generating combined savings of 24 million euros annually and avoiding 635,000 tonnes of CO₂. At urban scale, Rotterdam has replicated this concept with its Circular Rotterdam programme, connecting more than 50 companies in the port and local industry across 15 symbiosis chains that exchange residual heat, process water and by-products, with transactions valued at 180 million euros in 2022.

Public policies driving the circular economy in the urban context are structured across three levels: regulatory, fiscal and investment. The EU Waste Framework Directive (2018/851) sets binding recycling targets of 55% for 2025, 60% for 2030 and 65% for 2035, with a ban on landfilling recyclable waste from 2030. At municipal level, Paris approved its Plan Economie Circulaire in 2017 with 15 concrete actions and a budget of 20 million euros, including the creation of 5 ressourceries (repair and reuse centres) that handle 3,500 tonnes annually of items and generate 120 social-inclusion jobs.

Financing the circular transition mobilizes growing public and private funds. The European Investment Bank (EIB) dedicated 3.4 billion euros to circular economy projects in 2022, 34% more than in 2020. The Horizon Europe programme allocates 1.8 billion euros (2021-2027) to circularity research, of which 420 million target urban solutions. At municipal level, green bonds issued by cities have financed circular projects worth 2.1 billion euros globally in 2022, according to the Climate Bonds Initiative. Amsterdam issued a green bond of 600 million euros in 2023 partly earmarked to fund its circular strategy, with a 300% oversubscription that evidences market confidence in the profitability of the urban circular transition.