Chapter 2 - Energy Efficiency of Reverse Osmosis

Abstract

Energy efficiency of desalination by reverse osmosis has increased significantly over the last five decades. This increase in energy efficiency can be attributed to advances in membrane chemistry, module design, higher efficiency pumps, higher efficiency energy recovery devices, and innovative system designs. In this chapter, the authors will present analysis of specific energy consumption of a state-of-the-art reverse osmosis desalination. Analysis will be done based on fundamental thermodynamics and kinetics-based arguments with cost perspectives in reverse osmosis systems. Such analysis lays groundwork for understanding the current state of the art and the gap between current state of the art and practically achievable energy efficiency in reverse osmosis and membrane desalination systems in general. A roadmap for future research in desalination built from such analysis will be discussed. Tradeoff between capital costs, operating cost, and energy consumption will also be discussed along with value of novel membrane materials and other research opportunities with impact on energy consumption and cost of water.