RO-PRO desalination: An integrated low-energy approach to seawater desalination

Jeri L. Prante, Jeffrey A. Ruskowitz, Amy E. Childress, Andrea Achilli

Research output: Contribution to journalArticlepeer-review

160 Scopus citations


Although reverse osmosis (RO) is currently the most energy efficient desalination technology, it still requires a great deal of energy to create the high pressures necessary to desalinate seawater. An opposite process of RO, called pressure retarded osmosis (PRO), utilizes the salinity gradient between a relatively fresh impaired water source and seawater to produce pressure and hence, energy. In this paper, PRO is evaluated in conjunction with RO, in a system called RO-PRO desalination, to reduce the energy requirement of seawater RO desalination. RO-PRO specific energy consumption was modeled using RO conditions at the thermodynamic restriction and a newly developed module-based PRO model. Using a well-characterized cellulose triacetate (CTA) membrane, the minimum net specific energy consumption of the system was found to be approximately 40% lower than state-of-the-art seawater RO. A sensitivity analysis was performed to determine the effects of membrane characteristics on the specific energy production of the PRO process in the RO-PRO system. The sensitivity analysis showed that the minimum specific energy consumption using virtual membranes is approximately 1.0kWh per m3 of RO permeate at 50% RO recovery and that a maximum power density of approximately 10W/m2 could be achieved.

Original languageEnglish (US)
Pages (from-to)104-114
Number of pages11
JournalApplied Energy
StatePublished - May 1 2014
Externally publishedYes


  • Desalination
  • Pressure retarded osmosis
  • Reverse osmosis
  • Salinity gradient

ASJC Scopus subject areas

  • Mechanical Engineering
  • General Energy
  • Management, Monitoring, Policy and Law
  • Building and Construction
  • Renewable Energy, Sustainability and the Environment


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