Modeling simple trigeneration systems for the distribution of environmental loads

Integration of thermoeconomics and Life Cycle Analysis was carried out within the framework of an Environmental Management Information System. This combined approach identified where environmental loads were generated and tracked environmental loads throughout the system, allowing for a more precise understanding of operational activities. A trigeneration system was modeled, providing electricity, heat, and cooling to a building. The trigeneration system consists of a cogeneration module, auxiliary boiler, absorption chiller and electrical chiller. The trigeneration system model is flexible, as it allows electricity from/to the electric grid to be purchased/sold, and part of the cogenerated heat to be wasted. Umberto software is specifically designed to analyze the distribution of material and energy resources throughout a productive system. The software is based on Petri networks, double-entry bookkeeping and cost accounting, allowing the setup of complex systems and also a combined material, energy and inventory calculation. An assistant was built to include the tracking of emissions through the application of algebra and rules similar to those used in thermoeconomic analysis. It is possible to evaluate the environmental impact in terms of the consumption of natural resources and generation of emissions in the system, from the input of natural resources to the output of the final products. Network parameters were used to calculate the emissions associated with the operation of the system. The issue of allocating environmental loads was introduced and two scenarios for each operational mode were compared: the trigeneration system vs. a conventional energy supply system in which electricity was produced in a representative coal power plant. In this case the trigeneration system operated with significant reduction of the CO2 emitted into the atmosphere.

► Trigeneration system was modeled in an Environmental Management Information System.
► Life Cycle Analysis was formally combined with thermoeconomic analysis.
► An innovative environmental allocation method was proposed.
► It was possible to evaluate the process of formation of the environmental impact.
► Consumers can be informed of the environmental loads associated with the consumption of services.