Innovative Desalination System Driven by a Solar Micro Gas Turbine for Off-Grid Applications

Abstract

Past work by the authors has suggested that Solar micro Gas Turbines (SmGTs) can be used cost-effectively to produce electric power and heat for freshwater production through desalination, mainly in off-grid locations. This is further studied in this work, presenting a detailed description of system performance at design and part-load conditions, as well as the characteristics of the components of the SmGT and the desalination unit. To this end, the SmGT is assessed first, considering techniques that achieve a greater off-design performance such as incorporating Variable Inlet Guide Vanes (VIGVs) at the compressor inlet, and including the sensitivity to control strategies and ambient conditions, exploring their expectedly very negative impact on the SmGT performance. Water treatment system is comprised of two elements. A Reverse Osmosis desalination unit is driven by the electric power produced by the SmGT. This produces brine with high salt concentration to be partially treated further in a Zero Liquid Discharge (ZLD) unit driven by the exhaust gases of the microturbine (at about 250-300ºC), where the sensible heat of this stream is harvested by the ZLD unit to “dry” and concentrate the effluent. Finally, the potential and the operational limitations of the ZLD system are discussed, supplemented by an experimental proof of concept where its feasibility was verified.