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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Kelly has worked in the environmental field for more than 20 years. As Director of Environment and TechEx Lead (Environment + Energy) for Australia and New Zealand, she drives business growth, technical leadership and capability development across the region.

Kelly’s work spans complex State Significant Infrastructure, international environmental and social assessments, and project governance roles. She’s played a key role in establishing feasibility and securing environmental approvals for some of Australasia’s largest infrastructure projects, including WestConnex (M4 East and M4–M5 Link) in Sydney and the Purari Hydropower Project in Papua New Guinea.

Known for her people-driven leadership, Kelly brings a clear, outcomes-focused approach with strengths in stakeholder engagement, project directorship and aligning environmental performance with our clients’ broader infrastructure goals.  

Tell us about what inspired you to join the industry.

I grew up in the 1980s during a time where environmental awareness was growing and the plight to protect our ocean mammals inspired a generation. My sustainability values formed by this exposure at a formative age, combined with frequent opportunities to spend time in nature, with my grandparents and wider family who were all gardeners and spoke fondly of these values.

I was lucky enough to spend my childhood visiting Oatley Regional Park, which contains 45 hectares of Sydney’s prime bushlands, 310 plants species and 107 bird species. The opportunity to study this biology and be part of protecting it was ultimately what drove me to make a career for myself in environmental consulting at a time when it was only burgeoning.

I started out as an ecologist, and early in my career developed a broad base of experience in smaller town planning and environmental consultancies. I’ve taken opportunities to gain experience in the full gamut of disciplines, from noise and air monitoring, koala surveys, water treatment, impact assessments, master-planning, project management, expert witness reporting, permitting, detailed design development and construction management. My ‘say yes’ mindset allowed for rapid growth in diverse skills and associated responsibility.

Having such a broad experience-base led me to realise that where I could make a material difference was by bringing an ‘ecosystem mindset’ to early phase project definition, connecting and collaborating with clients and in-house designers at an organisation like ArchTam.

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

My favourite types of projects overall are those where I can work collaboratively in shaping the project with a client. One that stands out was my role as the Australian Environmental Lead for the Purari Hydropower Project, a pre-feasibility project for a hydropower plant in Papua New Guinea (PNG). We assessed the potential to send power by cable from PNG and through a 1,300kilometre high-voltage transmission line to Far North Queensland (FNQ), Australia.

I collaborated closely with clients including EDF, Origin Energy and PNG Energy Developments Ltd, and ArchTam’s trans-Tasman team. The feasibility project focused on identifying, evaluating and refining high-voltage transmission corridor and route options across remote Pacific island regions. This involved navigating challenging terrain, including large, dense rainforests and wild rivers.

I coordinated our team’s reconnaissance mission by light aircraft over the Torres Strait Islands and Far North Queensland — an unforgettable career highlight. We conducted fieldwork and extensive GIS mapping to inform the design and multi-jurisdictional planning approval pathways of the project, to meet World Bank Sustainable Development Principles and Australian Commonwealth standards. We also conducted extensive in-country social mapping, including Indigenous and stakeholder consultations in both FNQ and PNG. These insights directly informed the development of stakeholder engagement strategies and Indigenous Land Use Agreement planning for future stages of this multinational energy transition project.

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

As Environment Lead, I oversaw the construction of a 17-kilometre desalination pipeline project through urban and contaminated areas, and across Botany Bay. This project delivered significant community benefits, most notably enhancing Sydney’s drinking water security during drought.

We engaged the community extensively during this project and embedded the local benefits we identified during this engagement. These benefits included the creation of a parkland on the shores of Botany Bay, adding beach accessibility platforms in the suburb of Kurnell and including public art along the pipeline route. Through our environment-led design approach, we successfully avoided adverse environmental and community impacts, while restoring native vegetation in the corridor adjacent to the nearby RAMSAR wetlands.

Our alliance that designed, permitted and delivered this project over a three-year period won several design and construction awards for our work.

Share a piece of career advice.

Say yes. Take on the less glamorous tasks and problematic projects, be collaborative and complete them well. You’ll reap the opportunities and choices that flow from this.

Don’t go dark on clients or your internal peers, especially if you have a delay or issue, get in front of it and show you’re acting fast to resolve it.

As you progress in your career, look for opportunities for your team and elevate their profiles in your networks, use your local, regional or global platform.

Lastly, stay curious, and think broadly about who else you can bring in to your team to solve your clients’ complex issues.

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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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Jonathan Cox is a chartered mechanical engineer and fellow at the Institute of Mechanical Engineers, and has over 25 years of experience in the hydropower industry delivering work in the UK, Nepal and more recently, parts of Africa.

What inspired you to join the industry?

I didn’t set out to be a hydropower engineer — hydropower engineering found me! That is a story too long for this article. I have always enjoyed maths, science, creativity in design, and problem-solving as an engineer, but mechanical engineering seemed to me the discipline that would allow most flexibility later in my career. I started off in the automobile industry and saw one model go from ‘clean sheet of paper’ to mass production in the Midlands, UK. Since then, I have worked in the renewable energy sector, mostly delivering hydropower projects. My introduction to hydropower was working for Nepal Hydro and Electric in Nepal. 

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

The Amfilochia Pumped Storage Hydro project in Greece is one of my favourite projects for several reasons. As it is currently in the detailed design and construction phase, it is interesting to be involved with issues that affect the actual construction and configuration of this legacy project. I say legacy, as a project of this scale should be operational well into the 22^nd century! Its significance is that it is one of the first in a wave of new pumped storage hydro projects that will facilitate the storage of energy (nominally 816GWh). These storage projects will enable the transition to fully renewable energy-based generation for the country’s grid. 

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

Clean sustainable, renewable energy — usually in ‘mains quality’ electrical form — has a positive community impact whatever the scale of the project. Some hydropower projects can be made a feature of multi-purpose dam projects. I am fortunate enough to have worked as the designer for the micro-hydro project retrofitted into the dam at Llys-y-frân Countryside Park in Pembrokeshire, Wales. I recommend visiting the park (whilst on a holiday in Pembrokeshire perhaps) to see the micro-hydro powerhouse building. It has also been most satisfying for me to have been involved with the projects for the charity Christian Engineers in Development; these projects are often ‘off-grid’ bringing power to a remote community. 

Share a piece of career advice. 

Remember that you are on a journey. Try to leave the world a better place than the one you have inherited, whether that is investing in people, projects, the environment, or good values in society. Also, remember that your work fits into your life — not the other way round. 

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