Impact of solar energy cost on water production cost of seawater desalination plants in Egypt

Abstract

Many countries in North Africa and the Middle East are experiencing localized water shortages and are now using desalination technologies with either reverse osmosis (RO) or thermal desalination to overcome part of this shortage. Desalination is performed using electricity, mostly generated from fossil fuels with associated greenhouse gas emissions. Increased fuel prices and concern over climate change are causing a push to shift to alternative sources of energy, such as solar energy, since solar radiation is abundant in this region all year round. This paper presents unit production costs and energy costs for 21 RO desalination plants in the region. An equation is proposed to estimate the unit production costs of RO desalination plants as a function of plant capacity, price of energy and specific energy consumption. This equation is used to calculate unit production costs for desalinated water using photovoltaic (PV) solar energy based on current and future PV module prices. Multiple PV cells are connected together to form a module or a panel. Unit production costs of desalination plants using solar energy are compared with conventionally generated electricity considering different prices for electricity. The paper presents prices for both PV and solar thermal energy. The paper discusses at which electricity price solar energy can be considered economical to be used for RO desalination; this is independent of RO plant capacity. For countries with electricity prices of 0.09 US$/kWh, solar-generated electricity (using PV) can be competitive starting from 2 US$/W p (W p is the number of Watts output under standard conditions of sunlight). For Egypt (price of 0.06 US$/kWh), solar-generated electricity starts to be competitive from 1 US$/W p. Solar energy is not cost competitive at the moment (at a current module price for PV systems including installation of 8 US$/W p), but advances in the technology will continue to drive the prices down, whilst penalties on usage of fossil fuel will increase electricity costs from conventional non-renewable sources. Solar thermal is cheaper (at a current price of 0.06 US$/kWh) than PV; however, PV is more appropriate for Egypt (for the time being) as it is more applicable to the smaller RO plant sizes found in Egypt (up to 5 MW; 10,000–15,000 m 3/d product water capacity). We would expect that there will be a shift towards more centralized RO plants (larger size) in Egypt, to tackle the increasing water shortage, and this would then favor the adoption of solar thermal energy in the near future.