1. Title, Journal and Authors
Title: Energy and thermodynamic analysis of power generation using a natural salinity gradient based pressure retarded osmosis process
Authors: Wei He, Yang Wang, Mohammad Hasan Shaheed*
School of Engineering and Materials Science, Queen Mary University of London, E1 4NS, London, UK
Despite the potential of PRO process, the commercialization of the process isn't yet realized due to many technological obstacles, so that optimizing energy utilization is by far one of the most critical problems of PRO. In this study, the authors verified the fact that it is thermodynamically impossible to harvest all the usable latent energy of mixed solution, which resulted from the lower concentrated solution and the higher concentrated solution, just with one-stage PRO process. In order to verify the fact, the authors investigated the thermodynamic implications of power density and energy generation mathematically and found the necessity of multi-stage PRO process for harvesting increased amount of energy. Furthermore, the authors investigated the performance variation of two-stage PRO according to the feed solution arrangements (i.e., continuous feed and divided feed). All the aforementioned results indicate favourable energetic performance of the two-stage versus the one-stage PRO process in terms of the reduced frictional loss and unused energy involved in the process.
3. Originality & Creativity
- Power density and energy generation by PRO processes are mathematically interpreted.
- Configurations of two-stage PRO process are proposed and discussed.
- Energy generation is compared for different configurations.
4. Application to research
- Based on the results shown in the current study, we can make two different conclusions. First, stand-alone PRO (i.e., one-stage PRO) has a high probability that it isn't attractive in terms of energy. Second, the feed arrangement can seriously affect the performance of PRO processes so that we have to consider the factor as an important one. In designing PRO-basis processes such as RO-PRO hybrid process, therefore, these two other conclusions should be regarded as critical aspects.