Urban Governance and the Choreography of Intermediary Roles in a Waste Cooking Oil-to-Biodiesel Loop in Shiga Prefecture, Japan

Local circular-economy initiatives often stall not because conversion technologies are unavailable but because material flows, operational routines, and responsibilities must be aligned across heterogeneous actors. This article traces a four-decade waste cooking oil (WCO) to biodiesel fuel (BDF) loop in Shiga Prefecture, Japan, and explains how intermediary roles overlapped and migrated among civic groups, municipalities, and a local fuel distributor as the loop moved from experimentation to routine service provision. Based on interviews (n = 10), municipal and organizational documents, and process tracing, the analysis applies a four-mode intermediation lens—facilitating, brokering, configuring, and structuring—to map how actors addressed three recurring coordination challenges: mobilizing dispersed household feedstock, stabilizing quality and compliance in conversion and logistics, and securing reliable offtake through procurement and fleet routines. The findings show that durable circular loops rely on redundant intermediation: rather than a clean handover between actors, multiple intermediaries simultaneously perform different modes, creating fallback capacity when political priorities, markets for used oils, or operational constraints shift. The article distills transferable design principles—early offtake commitments, visible and convenient collection infrastructure, shared quality gates, and hybrid municipal–private operating models—for cities building local circular ecosystems.