Metrics Matter: Accurately Defining Energy Efficiency in Desalination
Energy cost contributes a large portion of the overall cost of desalinated water. Improving the energy efficiency of desalination plants is therefore a primary design goal. However, accurately evaluating and comparing the energy consumption of desalination plants that use different forms and grades...
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| Format: | Article |
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ASME International
2020
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| Online Access: | https://hdl.handle.net/1721.1/128163 |
| _version_ | 1811068856529059840 |
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| author | Bouma, Andrew Thomas Swaminathan, Jaichander Lienhard, John H |
| author2 | Massachusetts Institute of Technology. Department of Mechanical Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Mechanical Engineering Bouma, Andrew Thomas Swaminathan, Jaichander Lienhard, John H |
| author_sort | Bouma, Andrew Thomas |
| collection | MIT |
| description | Energy cost contributes a large portion of the overall cost of desalinated water. Improving the energy efficiency of desalination plants is therefore a primary design goal. However, accurately evaluating and comparing the energy consumption of desalination plants that use different forms and grades of energy is difficult, especially for power–water coproduction systems in which primary energy (PE) consumption leads to both salable electricity and potable water. The power plant converts PE into grades of thermal energy and electricity usable by the desalination plant. To fully capture the thermodynamic and economic cost of energy, and to fairly compare desalination systems that use different grades of input energy, we must compare energy consumption not at the point where energy enters the desalination plant itself, but as PE consumption entering the power plant. This paper investigates a variety of metrics for comparing the energy and exergy consumption attributable to desalination in coproduction plants. Previous results have shown that reverse osmosis (RO) is approximately twice as efficient as multiple effect distillation (MED) on a PE basis. We then compare the PE consumption of MED and RO from a thermoeconomic perspective. The entropy generation at the RO membrane and in the MED effects are derived in similar terms, which enables a comparison of the overall heat transfer coefficient in an MED system to the permeability of an RO membrane. RO outperforms MED in energy efficiency because of a balance of material costs, transport coefficients, and cost of energy. |
| first_indexed | 2024-09-23T08:02:07Z |
| format | Article |
| id | mit-1721.1/128163 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T08:02:07Z |
| publishDate | 2020 |
| publisher | ASME International |
| record_format | dspace |
| spelling | mit-1721.1/1281632022-09-23T10:26:03Z Metrics Matter: Accurately Defining Energy Efficiency in Desalination Bouma, Andrew Thomas Swaminathan, Jaichander Lienhard, John H Massachusetts Institute of Technology. Department of Mechanical Engineering Rohsenow Kendall Heat Transfer Laboratory (Massachusetts Institute of Technology) Energy cost contributes a large portion of the overall cost of desalinated water. Improving the energy efficiency of desalination plants is therefore a primary design goal. However, accurately evaluating and comparing the energy consumption of desalination plants that use different forms and grades of energy is difficult, especially for power–water coproduction systems in which primary energy (PE) consumption leads to both salable electricity and potable water. The power plant converts PE into grades of thermal energy and electricity usable by the desalination plant. To fully capture the thermodynamic and economic cost of energy, and to fairly compare desalination systems that use different grades of input energy, we must compare energy consumption not at the point where energy enters the desalination plant itself, but as PE consumption entering the power plant. This paper investigates a variety of metrics for comparing the energy and exergy consumption attributable to desalination in coproduction plants. Previous results have shown that reverse osmosis (RO) is approximately twice as efficient as multiple effect distillation (MED) on a PE basis. We then compare the PE consumption of MED and RO from a thermoeconomic perspective. The entropy generation at the RO membrane and in the MED effects are derived in similar terms, which enables a comparison of the overall heat transfer coefficient in an MED system to the permeability of an RO membrane. RO outperforms MED in energy efficiency because of a balance of material costs, transport coefficients, and cost of energy. 2020-10-23T17:27:10Z 2020-10-23T17:27:10Z 2020-10 2020-08 Article http://purl.org/eprint/type/JournalArticle 0022-1481 1528-8943 https://hdl.handle.net/1721.1/128163 Bouma, Andrew T. et al. "Metrics Matter: Accurately Defining Energy Efficiency in Desalination." Journal of Heat Transfer 142, 12 (October 2020): 122101 © 2020 ASME http://dx.doi.org/10.1115/1.4048250 Journal of Heat Transfer Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf ASME International Prof. Lienhard |
| spellingShingle | Bouma, Andrew Thomas Swaminathan, Jaichander Lienhard, John H Metrics Matter: Accurately Defining Energy Efficiency in Desalination |
| title | Metrics Matter: Accurately Defining Energy Efficiency in Desalination |
| title_full | Metrics Matter: Accurately Defining Energy Efficiency in Desalination |
| title_fullStr | Metrics Matter: Accurately Defining Energy Efficiency in Desalination |
| title_full_unstemmed | Metrics Matter: Accurately Defining Energy Efficiency in Desalination |
| title_short | Metrics Matter: Accurately Defining Energy Efficiency in Desalination |
| title_sort | metrics matter accurately defining energy efficiency in desalination |
| url | https://hdl.handle.net/1721.1/128163 |
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