Integration of multiple energy systems for the valorisation of the residual municipal solid waste: a modelling study

Integrating performant waste-to-energy solutions in composting facilities is essential to mitigate the pressure of increasing amounts of residual municipal solid waste. Hence, this paper investigates the integration of residual municipal solid waste gasification with a bottoming organic Rankine cycle (ORC) unit, a biomass pyrolysis reactor and a wastewater treatment plant from an energy point of view. Two layouts are compared to evaluate the system's flexibility in a district cooling and heating network with varying load demand. Results: The analyses show that pyrolysis can reduce the ORC partialisation and obtain a bio-crude oil annual production in the range of 9617 t⋅y−1 – 12718 t⋅y−1. When the wastewater treatment is decoupled from the ORC condenser (second layout), it is possible to treat all 16000 t⋅y−1 of wastewater produced. On the contrary, in the first layout, the amount of wastewater treated is affected by the ORC working fluid. Toluene (9391 t⋅y−1) treats more wastewater than cyclopentane (8762 t⋅y−1) since the operability of the treatment line is extended by 275 h. In both layouts, the electricity production is higher with toluene, ranging between 341 and 5185 kWe. However, the highest natural gas savings, 1783990 m3⋅y−1, is obtained with cyclopentane.