Flexibility assessment of a combined heat-power system (CHP) with energy storage under real-time energy price market framework

The use of on-site generation can significantly enhance the primary energy savings of a building while acting as a hedge against rising electricity prices. Among other techniques, combined heat and power systems have proved to be reliable and economically suitable technologies in building applications and provision for their promotion has been set out by the European Union over the last few years. Moreover, demand side management programs can provide additional revenue streams which can further benefit the feasibility of combined heat and power technology in a commercial building while providing services to the grid network. In this context, the aim of the present paper is to investigate the techno-economic performance and energy flexibility potential for demand response programs of a gas turbine combined heat and power unit with thermal and electrical storage in commercial buildings. A short assessment overview on demand side management and demand response programs, with a special focus on combined heat and power systems, is provided to introduce the main aspects of these initiatives. Combined heat and power system, technical parameters and operating control strategies are investigated to determine their effects on system efficiencies and economics. Finally, real time pricing and energy storage are examined to establish the implications on a combined heat and power system in a demand-side management framework. Results show that savings of 7% can be obtained by the introduction of thermal energy storage systems, making them suitable for combined heat and power systems in building applications. Operating in a real-time market, the year-on-year savings associated with the combined heat and power are greater than when fixed rate tariffs are considered, especially with the electric energy storage system installed, since it allows the exploitation of price fluctuations. However, the current high investment cost of electric storage makes this solution economically unsuitable, leading to poorer combined heat and power economic performance.