Practical tools for the design optimization of multi-energy systems: sizing of cogeneration engines in industry and aggregation of users into energy communities

The objective of the work is to develop calculation tools for optimizing the design and operation of energy and industrial systems. In doing so, two practical cases will be addressed. The first case concerns the optimization of the rated power (size) of natural gas cogeneration systems serving industrial or tertiary users that require flows of electricity and heat (and possibly cooling) and which may include other generation systems (e.g. photovoltaic). The purpose is the maximum economic saving considering a reference operating period (e.g. one year), the technical data of the generation units, the real consumption and cost data deriving from field measurements, appropriate documentation (e.g. bills) or from energy markets and possibly weather forecasts. Part of the activity involves identifying a structure for organizing and collecting the data required by the calculation model that is applicable to various practical cases. A uniform format is defined for daily data and situations. To keep the procedure simple to use even by non-expert persons, and to obtain clear results, the only decision variable is the engine size. All the other variables are fixed as parameters. The chosen value defines its operational limits and efficiency, considering two control strategies (electrical and thermal tracking) as usually implemented by the control units of commercial engines. Emphasis is given to the identification of a 'unique form' of data required as input by the procedure, and to its estimation from the usually inhomogeneous information available (e.g. quarter-hourly curves, direct measurements, cumulative consumption by tariff rate, monthly consumption). The procedure is implemented in order to calculate economic savings and incentives of a cogeneration unit following electrical or thermal tracking choosing the best option. The second case concerns the best aggregation of energy users (consumers, producers and prosumers) in energy communities in a specific geographical area, i.e. the area that belongs to the same primary electrical substation. Critical aspects as Demand Response programs, cost allocation criteria, aggregation of different consumption sector users and social issues are studied. An analysis of the tools proposed in the literature for the automatic search of users within the area based on the type (e.g. commercial, industrial activities, etc.) and their electricity demand (e.g. energy-intensive users) are carried out to lay the foundations for a future activity aimed at optimization. An example of a new member joining an Energy Community is proposed to understand the benefits of both sides considering economic and environmental performances.