Optimization framework of clean heat and CO₂ supply for agricultural greenhouses exploiting industrial symbiosis

The rising demand for greenhouse cultivation poses a challenge in providing environmentally friendly energy to maintain favorable greenhouse indoor conditions. This research presents an optimization model to identify cost-optimal symbiotic pathways to replace the import of three key greenhouse crops (tomato, cucumber, lettuce) with local greenhouse production. The proposed solutions involve greenhouses that can meet these crops' heat and CO₂ demands via industrial symbiosis. Switzerland is investigated as the case study, and the (waste) heat suppliers are municipal solid waste incinerators, cement production plants and biogas plants. Upgrading biomethane production plants are also considered potential CO₂ suppliers. The objective is to minimize the discounted cost when replacing 25%–100 % of vegetable imports with local agricultural greenhouses, considering availability of suitable land as well as waste heat and CO₂ suppliers. Optimization results suggest prioritizing northeast and west Switzerland for greenhouse development, due to the availability of suitable land and proximity of waste heat and CO₂ suppliers. Waste incinerators could provide 50%–70 % of the necessary heat, while Organic Rankine cycle in cement plants could generate 63 % of the electricity of supplementary lighting demand of greenhouses. While tailored for Switzerland, the optimization framework's general formulation can be adapted also to other regions to optimize greenhouses' heat and CO₂ demands. The optimization code is provided open source for associated applications.