Thermodynamic-based cost allocation in low-temperature thermal grids in presence of distributed energy producers

Thermal grids are well-established technologies that can cover the thermal demands of buildings in a more sustainable way. The lower operating temperature will allow not only for the integration of heat produced by thermal renewable energy sources but also for the storage of surplus electricity from the grid using power to heat technologies. To ensure a wider diffusion of this technology, it is important to propose a method for the cost allocation among producers connected to the grid. In this regard, this paper proposes Exergoeconomics as a possible solution. To show the capabilities of the method, some operating scenarios are compared for a cluster of five buildings in the tertiary sector interconnected by a thermal grid, where heat is produced by a cogeneration unit, heat pumps, and an industrial process. Thanks to the exergy and exergoeconomic unit costs, insights into the cost formation process of the heat consumed by users are provided. Results indicated that the substitution of the cogeneration plant with a centralized heat pump and waste heat could reduce the unit exergy cost of the heat supplied to the users. In addition, the analysis revealed a great sensitivity of the heat unit cost to the price of the waste heat recovered from the industrial process.