Renewable Energy, a Clean Environment and Solar Desalination

Abstract

Renewable energy has been competing against fossil fuels for seven decades. Every 30 years or so, the costs associated with fossil fuels become high and renewable energy has become economic once again. Now fossil fuels are warming the planet and renewable energy could help the impact. Improvements in photovoltaic (PV) efficiency along with improved production have cut costs. Costs and production methods have also impacted solar thermal energy use. Heat from the sun is captured by reflecting surfaces that reduce losses. Solar thermal has become cost competitive with PV, especially when short-term storage (4–24 h) is required. Here, we look at the details of both solar thermal generally and solar desalination specifically. The Middle East North Africa (MENA) region is well suited to solar thermal applications because low humidity provides the region with high direct sunshine. Little is lost to light reflected by water molecules in the atmosphere. We look at the economics of various solar methods using the levelized cost of energy (LCOE). It is the sensitivity of LCOE to other system parameters such as power capacity, investment, and power generation that identifies the best ways to capture solar energy economically. Finally, the specific example of desalination is used to illustrate the differences between various solar options. Photovoltaic collection and reverse osmosis are compared in terms of capital cost and energy cost to concentrated solar thermal collection and multi-effect distillation. These two have the lowest capital costs and LCOE among the options available today.