Trigeneration system driven by the geothermal and solar sources

In this study, a novel trigeneration system is conceived to produce heat and electricity and to provide cooling for the health treatments and touristic facilities of a spa, based on the natural hot water and solar sources. The power generation components, individually considered, are commercially available ones, but their novel combination and the complex power flow management represented a challenge. The proposed system is composed of a low‐temperature driven adsorption chiller, thermally activated by a low enthalpy geothermal source, and by hybrid photovoltaic/thermal panels. In this way, multiple objectives are achieved: produce electricity and thermal energy by renewable sources; optimise the use of different renewable sources (geothermal and solar); use the energy available for free from a geothermal source also during summer (otherwise wasted) to produce a cooling effect, and in so doing, avoiding the huge electricity consumption of conventional air conditioning units in summer; reduce the temperature of the fluids released to the environment (in a natural reserve); reduce the CO2 emissions by 45% with respect to the present configuration, limiting the global warming. The mathematical models were experimentally validated using a pilot plant built on purpose, and the performance of the whole system was analysed and discussed.