Evaluating Water Batteries In Renewable Energy Storage

Portugal's new "water battery" plant showcases how pumped storage can revolutionize renewable energy storage.

What are water batteries in renewable energy?

The renewable energy sector is witnessing a potential breakthrough with the introduction of "water batteries". A Portuguese power plant, spearheaded by Spanish company Iberdrola with a €1.5 billion investment, demonstrates that pumping water up a mountain can play a crucial role in an energy system driven by renewable power.

The Mechanics And Impact Of Pumped Storage Plants

Iberdrola's facility, a pumped storage plant, utilizes a 230-tonne metal cylinder spinning at 600 revolutions per minute to move water 7 km up a mountain. This method of energy storage, termed a "water battery," is both simple in concept and intricate in engineering. It stores excess electricity from the grid, primarily from wind and solar power, in an upper reservoir. When fully charged, the water level reaches 885 meters above sea level. During peak demand, this process is reversed to generate electricity, with the plant's turbine capacity being an impressive 880 megawatts. It is capable of generating power for up to 24 hours, equivalent to charging 400,000 electric vehicle batteries or powering 2.4 million homes in Portugal for a day.

Tâmega giga battery - Iberdrola, Portugal
Tâmega giga battery - Iberdrola, Portugal

The Necessity Of Pumped Storage In Renewable Energy

The variability of wind and solar power presents a significant challenge, necessitating a reliable storage solution. In 2023, Portugal achieved 61% of its electricity from renewable sources, aiming for 85% by 2030, while Spain targets 81%. Pumped hydro storage, like Tâmega, is critical in balancing the grid, especially during periods of excess renewable energy production. This technology has been around for a century and remains a dominant form of global electricity storage.

Economic Viability And Global Expansion

The economic prospects of pumped storage plants are considerable. Iberdrola's strategy involves buying power at low prices and selling it back during high-demand periods. For instance, Portugal's off-peak and on-peak power prices on a recent Monday were €54 per MWh and nearly €78 per MWh, respectively. However, the high capital expenditure and lengthy construction periods, often opposed by local residents and environmentalists, pose challenges. Despite these hurdles, Iberdrola received a significant €650 million loan from the European Investment Bank for the Tâmega project.

A global leader in renewables energy - Iberdrola
Iberdrola: pioneers in renewable energies and leading the energy transition and the decarbonisation of the economy

The Future Of Pumped Storage In Energy Transition

The future of pumped storage in renewable energy is contingent on faster permission processes and regulatory stability. As the technology approaches its centennial, its relevance in modern energy systems is undisputed. With countries like the UK and Scotland having significant potential for pumped hydro, regulatory reforms are vital for attracting investment and advancing these projects. As the world transitions to renewable energy, the role of pumped storage as an efficient and reliable energy storage solution is increasingly crucial.


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