A systematic methodology for the environomic design and synthesis of energy systems combining process integration, Life Cycle Assessment and industrial ecology

This paper presents a systematic methodology for sustainable process systems design, combining the principles of industrial ecology, process design and process integration, Life Cycle Assessment (LCA) and multi-objective optimization (MOO). The superstructure considers an extended decision perimeter and embeds models based either on flowsheeting software or average market technologies, for which energy and material flows are extracted from the Life Cycle Inventory (LCI) database. Therefore, the overall supply chain can be synthesized within a given action system and the systematic recyclings identified. The methodology can be used to design eco-industrial parks or urban systems, to identify the best conversion pathways of resources or waste, or to fix the optimal value of environmental taxes. It is illustrated by an application to the environomic design of an urban energy system. This case study considers multiple energy services to be supplied and waste to be treated, with their seasonal variations, indigenous and imported resources, as well as different candidate conversion technologies. Results demonstrate that integrating an environmental objective in the design procedure leads to consider different system configurations than if only economic aspects are considered. The problematic of the optimal value of a CO2 tax is as well addressed. Nomenclature Ė− p net electrical power produced by system at the operating conditions of period p, in MWe Ė− t electrical power produced by the turbines of the cycle, in MWe ̇ fup quantity of functional unit involved during period p İO impact due to the operation phase ṁext extracted mass flow rate from EGS, in kg/s ṁf mass flow rate of geothermal steam passing through the flash system turbine, in kg/s ṁinj injected mass flow rate in EGS, in kg/s ṁi mass flow rate of emission of substance i from flash system condensers, in kg-i/kg-geofluid ṁmkup mass flow rate of make-up water for EGS, in kg/ ṁscal quantity of scaling and residues from EGS to be disposed, in kg/s