Metabolic heat and moisture reuse with climate-adaptive control for energy-efficient black soldier fly bioconversion in modular container farms

Abstract

Black soldier fly larvae (BSFL, Hermetia illucens) convert organic residues into feed ingredients and fertiliser. Climate control is a major contributor to the energy demand of container-based bioconversion. We developed a control-oriented dynamic model linking larval growth, substrate dynamics and container climate to heating, ventilation and air conditioning (HVAC). A two-level Model Predictive Control (MPC) strategy planned climate trajectories and tracked them through HVAC actuation. Four simulation studies examined controller selection, HVAC configuration, larval age pairing and inter-container coupling, using subsets of eight climate scenarios. Across the four scenarios tested for controller selection, dynamic MPC reduced specific energy consumption (SEC) by 31 to 61% and increased predicted dry biomass at harvest by up to 27.5% relative to single fixed setpoints. Under the tested controller settings, active cooling was required in the two hot scenarios, whereas dehumidification provided no additional operational benefit. Pairing larval ages four days apart within one container reduced SEC by up to 33% in the tested non-hot scenarios. In the Cooldry scenario, two age-separated containers connected by an actuated air duct produced 9.0% more biomass and achieved 3.9% lower SEC than two independent containers with mixed ages, despite using 4.6% more total HVAC energy. The simulations suggest that dynamic climate control and metabolic heat and moisture reuse can improve the energy intensity of BSFL bioconversion. The quantitative estimates and hardware recommendations require experimental validation before application to industrial facilities.