Energy management of a brackish water reverse osmosis plant using time-of-use electricity tariffs

Research Team in Thermal and Applied Thermodynamics (2.T.A.) Department of Engineering Sciences, Faculty of Sciences and Techniques Errachidia, Moulay Ismaïl University of Meknès, B.P. 509, Boutalamine, Errachidia, Morocco.

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Abstract

Reverse osmosis (RO) desalination has established itself as the main technology for obtaining drinking water in deserts and dry areas; nevertheless, it is still the most electricity-intensive consuming and energy-consuming operation of water purification processes. This study focuses on the demand-side energy management strategy that was applied in a fully operational brackish water RO desalination plant in southern Morocco to maximize the use of electrical energy according to time-of-use (TOU) electricity tariffs. Real-time data from the plant’s actual operation were used for analysis to determine the interrelationship between electrical load demand (in kW), water production rate, and the various tariff periods. The development of a cost-oriented energy model enabled the evaluation of different operational scheduling scenarios that are based on high-load and low-load operating windows. The findings reveal that the operational scheduling of the RO process for production in reduced electrical demand periods not only decreases specific energy consumption and unit water production cost but also avoids the need for infrastructure expansion, renewable energy integration, or major process changes. renewable energy integration, or major process changes. The suggested approach for conducting TOU-based load management is a feasible, inexpensive, and simple to implement solution that could provide all reverse osmosis desalination plants with electrical energy efficiency and economic performance gains, particularly the ones situated in dry and poorly-off areas.