Analysis of a domestic trigeneration scheme with hybrid renewable energy sources and desalting techniques

In this paper, experimental tests of a hybrid trigeneration pilot unit based on renewable energy sources are presented and analyzed. The plant provides electricity by coupling four photovoltaic/thermal collectors and a micro-wind turbine, fresh water by means of hybrid desalination (membrane distillation, and reverse osmosis), and sanitary hot water coming from the photovoltaic/thermal collectors and an evacuated tubes collector. Plant design was previously modeled to cover the power, freshwater and sanitary hot water for a typical family home (four residents) isolated from the power and water networks. The hybrid pilot unit has been tested from May 2017 to March 2018 in Zaragoza (Spain). Results from those tests show that daytime assessment of power, freshwater and sanitary hot water produced allowed a good coverage of scheduled energy and water demands. Flexible operation due to the combined production of power and heat was also observed. State of charge of the batteries and the temperature of the sanitary hot water tank are the key control variables, which allow to give priority to power, freshwater or sanitary hot water production according to the ordered demands or economic incentives. Environmental assessment of the pilot unit along its life cycle also has shown very low impacts with respect to the conventional supply of energy and water.