A thermodynamic platform for evaluating the energy efficiency of combined power generation and desalination plants

Abstract
In seawater desalination, the energy efficiency of practical processes is expressed in kWh_electricity or low-grade-heat per m3 of water produced, omitting the embedded energy quality underlying their generation processes. To avoid thermodynamic misconceptions, it is important to recognize both quality and quantity of energy consumed. An unmerited quantitative apportionment can result in inferior deployment of desalination methods. This article clarifies misapprehensions regarding seeming parity between electricity and thermal sources that are sequentially cogenerated in power plants. These processes are represented by heat engines to yield the respective maximum (Carnot) work potentials. Equivalent work from these engines are normalized individually to give a corresponding standard primary energy (QSPE), defined via a common energy platform between the adiabatic flame temperature of fuel and the surroundings. Using the QSPE platform, the energy efficiency of 60 desalination plants of assorted types, available from literature, are compared retrospectively and with respect to Thermodynamic Limit.

Citation
Ng, K. C., Burhan, M., Chen, Q., Ybyraiykul, D., Akhtar, F. H., Kumja, M., … Shahzad, M. W. (2021). A thermodynamic platform for evaluating the energy efficiency of combined power generation and desalination plants. Npj Clean Water, 4(1). doi:10.1038/s41545-021-00114-5

Acknowledgements
Authors would like to thank KAUST for the generous funding of the research and Northumbria University, UK for their research contributions. R.W.F. has been partially supported by an APEX award on Exploring Water Re-use—the Nexus of Politics, Technology and Economics from the Royal Society and British Academy with funding from the Leverhulme Trust.

Publisher
Springer Science and Business Media LLC

Journal
npj Clean Water

DOI
10.1038/s41545-021-00114-5
10.1038/s41545-021-00120-7

Additional Links
http://www.nature.com/articles/s41545-021-00114-5

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