From Australia to Portugal, the “Water Battery” Supporting the Global Energy Transition

How can we generate clean energy only when it’s needed? With a “water battery,” known worldwide as a “water pump battery”. This term refers to pumped hydro energy storage (PHES), designed to produce energy by harnessing the movement of water. This system is increasingly popular and can be found across Europe, the United States, China, and Australia.

The concept is simple. During times when energy production exceeds demand, the surplus (instead of being wasted) is used to power turbines that pump water through a series of tunnels from lower elevations to a higher point. When energy demand is high and alternative sources like wind and solar are insufficient, the upper reservoir’s gates open, and water rushes downhill, driving turbines to generate electricity.

According to a recent Stanford University study, managing water storage in these plants is the most efficient and sustainable method to ensure energy stability across the power grid. This is why developed countries are investing in this technology, which is seen as a crucial tool for achieving a green economy.

Today, as the world shifts toward green energy (Europe aims to meet 50 percent of its energy needs with wind by 2030), the pumped hydro energy storage schemes are playing an important role in supporting sustainable development. According to the International Energy Agency, over 90 percent of the world’s stored energy depends on PHES.

Among the biggest investors in this technology are Australia, the United States, China, and Europe. In the United Kingdom, four major PHES are operational in Scotland and Wales. The British energy authority estimates that the UK needs plants with five times the current storage capacity to achieve 100 percent clean energy by 2050. In October, the government announced an energy development plan that includes building new pumped hydro energy storages. «This plan will improve our energy storage capacity,» said Energy Minister Michael Shanks. «We’ll be ready when solar and wind are insufficient for our needs.»

Another advantage of PHES, highlighted by a British government study, is the ability to hold at least 20 GW of energy translates to the government saving £24 billion (€28 billion) in energy bills between 2025 and 2050.

Staying in Europe, Portugal has invested over €1 billion in constructing the Tâmega Gigabattery, the country’s PHES, with a capacity exceeding 1.1 GW. It will generate enough energy to recharge 400,000 electric vehicle batteries or meet the daily needs of 2.4 million households. The Tâmega project supports Portugal’s goal to generate almost all its energy from renewable sources; currently, 61 percent of its energy comes from renewables. It wants to reach 85 percent by 2030.

In Australia’s Snowy Mountains in the state of New South Wales, a similar scheme has operated for years. The most established, Snowy Scheme, was inaugurated in 1974 firstly for the purposes of irrigation and secondly for electricity generation for NSW, Australian Capital Territory and Victoria. Currently, this vast system comprises eight power plants, 16 dams, 80 kilometre of aqueducts, and 145 kilometre of interconnected tunnels.

Today, a major pumped hydro expansion, known as Snowy 2.0, is underway by owner Snowy Hydro Limited, and constructed by the Webuild Group and its Australian subsidiary Clough in the Future Generation Joint Venture. It will increase Snowy Hydro’s generation capacity from 4.1 to 6.3 GW. Water from the Tantangara reservoir, situated at 1,230 metres above sea level, will travel through a 10-metre diameter tunnel, then descend 700 metres to the lower Talbingo reservoir at 540 metres above sea level. The centrepiece of the project is the hydroelectric plant, located 800 metres deep in the mountain and encompassing 523,000 cubic metres, making it the largest of its kind at this depth.

By increasing the scheme’s pumped storage capacity, Snowy 2.0 will be able to generate enough flexible and quickly dispatched electricity to power three million homes for a week. It will also stabilise the East Coast of Australia’s electricity grid and prevent the emission of 10 million tons of CO₂ annually.