Water desalination using solar energy : value engineering and cost benefit analysis

Abstract

This study examines several technical and financial aspects of solar driven desalination plants and focuses on the feasibility of replacing gas turbine and fuel oil fired plants by concentrated solar power plants to develop sustainable green energy projects. For this purpose, a comprehensive literature review of the evolution and state of the art desalination and solar energy technologies was coupled with a value engineering (VE) methodology to identify two optimal solar driven desalination plant configurations from a set of five possible scenarios based on technical and financial considerations. A cost benefit analysis (CBA) was then performed on the “two most positively assessed” configurations to evaluate the return on investment. A sensitivity analysis was then conducted on Total Water Cost (TWC) values for plant capacities ranging between 25,000 and 75,000 m³-day based on 2020 market values. Finally, special economic enhancement schemes were proposed by introducing a progressive periodic subsidy reduction on water and-or electricity end user unit rates under private public partnership (PPP). The deficit between income from public subsidy and capital costs was capped by reducing water unit rates subsidy. The results of the VE showed that for public sector funding, the Reverse Osmosis (RO) desalination powered by photovoltaics supplemented by a smart grid will yield the lowest TWC of $1.22-m³ (GCC) and $1.24-m³ (Mediterranean countries) for a plant capacity of 50,000 m³-day. Multi Effect Distillation (MED) powered by parabolic troughs supplemented by fuel fired power plant will yield a TWC of $1.62-m³ (GCC) and $1.69-m³ (Mediterranean countries). The CBA results showed that investing in solar powered desalination plants is most attractive for the public sector. One special economic enhancement resulted in a deficit of $149M. The revised water tariff rates were reduced by 3percent compared to the TWC of scenario D calculated during the VE assessment. The other ec