Total Site Utility Systems Structural Design Considering Environmental Impacts

The aim of this study is to optimise the structural design of a central utility system for a Local Integrated Energy Sector, considering its environmental performance, such that Total Annual Cost is minimised Environmental performance is captured by Greenhouse Gas emissions, Water, and Particulate Matter (PM) Footprints. To obtain the minimum cost solution, a Utility Systems Planner (USP) tool has been developed within the P-graph framework using a superstructure. The USP is applied to a case study with a chemical processing site and district energy demands. With the historically lower than average coal prices, the optimisation favours a utility system based on a coal boiler (68.4 MW) supplemented by geothermal clean energy plant (3 MW) to satisfy the 53 MW of process heat. Increasing the GHG emissions price from 5 (sic)/t to 20 (sic)/t shifts the optimisation in favour of natural gas as the primary fuel. Further increases in GHG prices to 95 (sic)/t changes the optimal solution to biomass as the fuel with geothermal heat. Solitary focus on GHG emissions and its price, however, overlooks the immediate environmental impact of PM. Policy constraints on PM emissions to be at a safe level reverts the optimal solution to use natural gas as the fuel.