Pumped storage: Europe’s renewable battery

Europe increasingly relies on wind and solar power, but their intermittent nature brings significant challenges. A proven solution lies in pumped storage hydropower — a mature technology that effectively acts as a massive, rechargeable battery. PSH stores excess renewable energy by pumping water uphill, releasing it to generate electricity exactly when it’s needed, providing reliable, flexible power on demand.

Currently, Europe has around 55 gigawatts of pumped storage capacity. Yet, according to the Outlook, we must more than double this capacity by 2050 to reliably support the EU’s energy transition and achieve net zero (p. 24).

Tackling Europe’s ageing hydropower infrastructure

Europe faces an urgent infrastructure challenge: nearly 70 percent of our pumped storage facilities are over 40 years old. These ageing plants need significant modernisation to remain efficient and safe (p. 22). Upgrading existing facilities offers a practical, cost-effective, and rapid route to increasing renewable storage capacity compared to building entirely new plants.

This need for modernisation is also a chance to introduce digital technologies — such as artificial intelligence, more sophisticated predictive maintenance and improved remote monitoring — to boost operational efficiency and minimise down time.

Barriers to new pumped storage development

Despite strong support from developers and grid operators, Europe’s progress on new pumped storage hydropower projects remains slower than desired. High upfront investment — typically exceeding £1 billion per gigawatt of installed capacity — can discourage potential investors. Complex permitting processes, lengthy project timelines, construction risks, and limited availability of specialist contractors and equipment also hold back development.

The Outlook contrasts Europe’s slower pace with the rapid pumped storage growth seen in countries with centralised economies, such as China. However, positive policy changes are emerging. For instance, the UK’s introduction of a ‘cap and floor’ financial model seeks to strike a balance by giving investors greater certainty, while ensuring affordability for consumers and taxpayers.

Addressing these barriers will be crucial if Europe is to fully harness pumped storage’s potential for a secure, renewable energy future.

Sustainability is non-negotiable

The Outlook emphasises that Europe’s pumped storage expansion must prioritise sustainability. In a region where environmental regulations and public expectations are high, careful planning, rigorous environmental assessments, and meaningful engagement with local communities are crucial.

Digital innovation powering progress

Europe is uniquely placed to lead in hydropower digitalisation. The Outlook underscores the transformative impact of digital solutions on pumped storage facilities (p. 46). Digitalisation doesn’t just make pumped storage operations more efficient — it significantly reduces environmental impacts and operational costs.

The question is pace

Across Europe, the need for grid-scale storage is widely recognised. The challenge isn’t awareness — it’s action. Governments and energy providers understand that without substantial investment in pumped storage, the transition to a low-carbon energy system won’t be achievable or reliable. The real question now is how quickly we can deliver the infrastructure needed to support it.

At ArchTam, we’re committed to supporting this important transition. With our global expertise and local knowledge, combined with a focus on sustainability and innovation, we’re ready to help Europe accelerate the rollout of pumped storage.

Explore the full 2025 World Hydropower Outlook here.

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Patrick Willis is a skilled project manager and civil engineer with over 18 years of planning, design and construction experience working on dam and hydropower projects and leading interdisciplinary project teams. He is passionate about transformative projects that balance infrastructure development with environmental stewardship. Whether it’s rehabilitating critical dams, modernizing hydropower systems, or pioneering pumped storage projects, he is inspired by the potential to make a lasting impact on communities.

Tell us about what inspired you to join the industry.

I’m originally from rural Vermont, where my passion for engineering began. My father, a geotechnical engineer, ran a small engineering business, and from a young age I helped him around the office and did field work, surveying, and geotechnical investigations. My love for math, science and the outdoors led me to pursue a degree in environmental engineering at Tufts University. Combining these interests has been at the core of my career ever since.

ArchTam has allowed me to merge my focus on the environment and sustainability with infrastructure development. Our work in hydropower and pumped storage aligns with my personal goals, especially as the pumped storage market plays a critical role in the energy transition. It provides the long-duration energy storage needed to bring more wind and solar power online, and I’m excited to contribute to this important effort.

What is your favorite ArchTam project that you’ve worked on and why?

One of the most exciting projects I’ve worked on at ArchTam is the proposed Lewis Ridge Pumped Storage Project in eastern Kentucky. This 287-megawatt project, led by Rye Development, is more than just an engineering challenge; it’s a symbol of transformation. Coal industry jobs in southeastern Kentucky have sustained a significant loss in the transition away from coal, creating a significant economic impact. This project is located on a former coal mining site and will repurpose impacted land to bring economic revitalization to the community. At the same time, it’s playing a critical role in our energy transition, enabling more renewable energy to come online.

As the project manager, I’m leading a talented team of 50 individuals through the preliminary design phase. This project represents a long-term commitment to sustainability and community impact. I’m incredibly proud to be part of an effort that addresses economic, environmental, and energy challenges all at once.

Tell us a story of how your work positively impacted the community.

My work at ArchTam often intersects with meaningful community impact, and the Bureau of Indian Affairs (BIA) Dam Safety Program is a great example. This BIA Dam Safety program oversees the safety of approximately 140 high-hazard dams on tribal lands. We’ve supported the BIA for several years with a dedicated team based in Denver, and I serve as the overall program manager.

Many of these dam structures are over a century old and in need of critical rehabilitation. There is limited information available on them, and many have been neglected over time, posing significant risks, including potential failure that could devastate downstream communities. Through this program, my team and I support the BIA to assess, prioritize, and design improvements for these dams, ensuring safety for tribal communities and preserving vital infrastructure.

Share a piece of career advice.

One piece of advice I always share with younger team members is this: whatever task you’re given, especially by leaders that you look up to, knock it out of the park. Develop a reputation of dependability. Delivering excellence, no matter how small or large the task, builds trust and opens doors to new opportunities. It’s something I’ve tried to practice throughout my career, and it’s a principle that has served me well in building relationships and advancing in this field.

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