The Dubai Electricity & Water Authority (Dewa) has issued tender documents to prequalified contractors for the main engineering, procurement and construction (EPC) contract for its planned Hatta 250MW pumped-storage hydroelectric project.

According to sources close to the project, contractors have been invited to submit proposals by 16 September.

In June last year, Dewa awarded a AED58m ($15.8m) contract to France’s EDF to provide consultancy services for the pumped-storage project. The state utility announced this week that EDF had completed engineering studies for the proposed project, including design, geological, hydro-geological, environmental, geotechnical and deep excavation studies.

The hydro project will use water stored in the Hatta Dam, near the Oman border. The existing Hatta Dam can store up to 1,716 million gallons of water. The project will involve the construction of an upper reservoir, which will be able to hold up to 880 million gallons. The upper reservoir will be located 300 metres above the dam level.

During off-peak hours, turbines will use solar energy to pump water from the dam to the upper reservoir. The project will support the AED1.3bn ($354m) Hatta development plan, which was announced earlier last November.

Dewa is planning to develop another pumped-storage hydro project as part of its plans to develop renewable energy with storage capacity to meet its ambitious long-term energy diversification targets. The emirate is planning for 75 per cent of its total energy requirements to be produced by clean energy resources by 2050.

In January, Dewa signed a memorandum of agreement (MoA) with the GCC Interconnection Authority (GCCIA) and the Belgian Dredging, Environmental & Marine Engineering Group (DEME) to conduct a study for a 400MW pumped-storage hydropower island in the Gulf area. The planned project would have a storage capacity of about 2,500MWh.

The appeal of pumped storage is that it can be integrated with different renewable energy sources such as wind and solar power, power supply options that are intermittently affected by wind patterns and cloud cover. Pumped storage is an important source for energy storage as water is stockpiled when excess energy is produced. This can then be used to provide electricity when energy demand is highest during peak hours.