Silent Waterfalls – A Review of Salinity Gradient Osmotic Energy Conversion Technologies

Abstract

Many leaders of industrial countries, at the COP26 UN climate change conference in November 2021 in Glasgow, Scotland, pledged net-zero emissions by 2050. Also, 12 states and 160 cities in U.S. have pledged to obtain100% of their electricity from clean sources. This should revitalize interest in the search of new clean energy sources that could feasibly replace fossil fuel combustion driven power cycles. It was demonstrated in 1954 that an untapped sustainable energy source is salinity gradient (SGE). The energy produced from water salinity is a clean, non-polluting and free of CO2 emissions with minimal environmental effects and is available on a continuous basis. There are different techniques for converting salinity gradient energy to electricity making it an attractive research topic that should be included in today's energy curricula and textbooks to prepare students for tomorrow's diverse energy supply. To better prepare students, undergraduate topics should include electrochemistry as well as battery and super capacitor energy storage. Thermodynamic courses should cover chemical potentials, solutions, and flow through membranes to analyze SGE. If the goals of the COP26 are going to be met by 2050, current engineering students will not be designing Rankine cycle power plants, but alternative energy systems. An in-depth review of the above-mentioned techniques, along with examples of the benchtop undergraduate research experiments with Pressure Retarded Osmosis (PRO) and Reverse Electrodialysis (RED) conducted at Wentworth and graduate level research experiment with mixing entropy battery (MEB) conducted at Northeastern will be given in this paper to illustrate the need for curriculum revision to prepare students to design and simulate zero emission technologies.