Greece is launching a pilot study to test a system that could combine renewable energy, pumped-storage hydropower and desalination to address both energy and water needs on the country’s islands.
The Ministry of Environment and Energy is examining a floating desalinated-water reservoir with a capacity of 10,000 cubic meters as a key component of a pilot pumped-storage facility. The project, which has a budget of €37,200, is expected to be completed by the end of 2026.
The initiative brings renewed attention to a much larger plan announced two years ago to develop hybrid projects on Greek islands using renewable energy, water storage and desalination. That broader program was allocated €200 million from the Islands Decarbonization Fund but has yet to move to the tendering stage.
A reservoir that can act as a battery
The pilot study will examine both conventional and nonconventional solutions for the reservoir under real-world conditions.
The structure will be built as a smaller-scale replica of the type of infrastructure envisioned for a full-size installation and tested at sea. It will include winches designed to be used in the full-scale construction to lift ballast and fold the reservoir’s membrane.
Testing will examine the reservoir’s mechanical operation and hydrostatic behavior using a pump, piping, vessel, crane and other necessary support equipment. The goal is to establish whether the underlying technology can function as intended.
The reservoir is being designed as a central component of a pilot pumped-storage system, in which water can serve both as a source of drinking water and as a means of storing energy.
The concept is particularly relevant to islands, where electricity demand rises sharply during the summer while water resources face increased seasonal pressure.
How the system would work
The broader concept is based on combining renewable energy sources, particularly wind and solar power, with pumped storage and desalination.
Electricity generated by wind turbines and solar panels could be used to pump and store water. The stored water could then be used to generate electricity when demand requires it.
At the same time, water produced through desalination facilities could help meet the increased demand for drinking water on the islands.
The approach was previously a key part of the planning of the Environment and Energy Ministry’s former leadership. In summer 2024, then-Environment and Energy Minister Theodoros Skylakakis announced that €200 million from the Islands Decarbonization Fund would be allocated to new hybrid projects combining renewable energy, pumped storage and desalination.
The funding was presented as a way to address the islands’ energy and water pressures simultaneously.
€200 million plan remains on hold
In November 2024, when the Islands Decarbonization Fund was activated, the €200 million was incorporated into plans for projects combining renewable energy with desalination and pumped storage.
The funding was expected to be directed primarily toward the Cyclades, where water shortages are a significant problem, as well as other Aegean islands.
However, two years after the original announcement, the tender for the projects has not yet moved forward.
The new pilot study is being funded through Greece’s National Development Program under the “Provision of Drinking Water and Water Management” category. Its purpose is to investigate and test a specific technological solution that could eventually support the wider concept.
The pilot project will therefore serve as a practical test of whether a system combining renewable power, water storage and desalination can operate under real-world conditions before the larger island infrastructure program moves ahead.
