This article traces the flow of municipal solid waste from southern Italy through a waste‐to‐energy facility and district heating system in Austria, examining the roles that waste's transformation from contaminant to commodity to fuel plays in interconnected, distributed, and contested urbanization processes. It contends that, while metabolic circulation hides socioecological costs in one place to facilitate valorization in another, specific spatial configurations emerge through territorialization—of waste economies, in this case—providing the spatial base to realize metabolic flows and to anchor political narratives. A decisive effect is that certain patterns of urbanization become locked‐in, impeding alternative metabolic transitions and spatial configurations. Attending to the coproduction of three sites—Naples, Italy; Zwentendorf, Austria; and St Pölten, Austria—through the circulation and transformation of waste and energy the article provides an empirical multi‐sited case study of a political ecology of urbanization.