Pumped Storage Hydropower (PSH) may be the key to unlocking Europe’s success in achieving its Green Energy Transition goals. With the new Paris Pledge (the Pledge) unveiled by the International Hydropower Association (IHA) at the International Forum on Pumped Storage last week, it is hoped stakeholders will make a collective commitment to accelerating its development across Europe.
What is PSH?
Unlike other renewable sources, PSH provides a means to store potential energy, helping to balance the grid when supply from other renewable sources is insufficient. The system works by moving water between two reservoirs at different elevations. When the grid is producing in excess, the system will use this energy to pump water to the higher reservoir. When demand exceeds supply, this water will then be released, flowing from the higher reserve to the lower. This will then flow through a set of turbines, which convert the movement into electricity.
Wind and solar power sources are expected to make up around 86% of Europe’s Generation Capacity by 2050. However, their output is heavily dependent upon weather conditions and, as such, are referred to as “intermittent” sources. PSH therefore bridges the gap in the grid, providing stability by storing excess energy and releasing it when needed.
PSH is essential for the future of Europe’s green energy initiatives. As renewable generation increases, so too does the need for flexible, long-duration storage solutions like PSH. This capability therefore reduces reliance on fossil fuels, in line with various climate and energy targets.
The Pledge
The Pledge represents “a collective commitment from the hydropower sector to provide the necessary long-term duration electricity storage to support sustainable, clean industrial growth and deliver the European Green Deal”. It is an actionable commitment from the hydropower sector to accelerate the deployment and integration of long-duration electricity storage, with a particular focus on PSH, as a cornerstone of Europe’s clean energy transition. The Pledge aims to enable the reliable integration of at least 86% of variable renewable energy sources in Europe’s generation mix by 2050, support sustainable and inclusive industrial growth, enhance energy security and system resilience, and deliver on the objectives of the European Green Deal and the EU’s climate neutrality targets. Furthermore, it seeks to foster cross-border cooperation and innovation in energy storage and grid flexibility, ensuring that Europe remains at the forefront of technological advancement and sustainability.
Although PSH achieved popularisation in Europe in the 1980s, it is hoped that the IHA’s recently announced Pledge both renews and accelerates investment into the technology. The Pledge is the result of collaborative efforts between the IHA and other key stakeholders and providers of hydropower sources. It is split into two parts: (i) the industry pledge; and (ii) the request for regulatory support. Through these strengthened aims and commitments, the Pledge seeks to position PSH as an indispensable enabler of Europe’s energy transition, supporting climate objectives, economic growth and energy security for decades to come.
The industry pledge calls on the hydropower sector to implement a number of collective actions such as investment in the resources required to implement and grow the PSH projects pipeline and to reinforce the European supply chain’s capacity to support the deployment of new PSH projects. In pursuit of these aims, the hydropower sector commits to substantially increasing investment in the development, modernisation and expansion of PSH projects, with the ambition of doubling Europe’s PSH capacity by 2050. The sector will strengthen and diversify the European supply chain to ensure the timely delivery of new PSH projects, prioritising workforce development, skills transfer and gender diversity initiatives. By adopting best-in-class technologies and digital solutions, the industry will maximise operational flexibility, efficiency and environmental performance across PSH assets. Engaging transparently with local communities, stakeholders and policymakers from the earliest stages of project development will be a priority, ensuring social acceptance and equitable benefit-sharing. The sector also pledges to monitor, report and mitigate environmental impacts through robust, evidence-based approaches, in alignment with EU sustainability standards, and to share data and best practices to accelerate innovation and reduce project lead times.
To support these industry commitments, the Pledge calls for regulatory support through immediate adoption of the Renewable Energy Directive III with explicit provisions for cross-border cooperation and innovative storage solutions. It urges policymakers to remove double grid fees and discriminatory network charges for all energy storage technologies, thereby ensuring a level playing field and recognising the system value of PSH. The introduction of revenue stabilisation mechanisms and long-term contracts, such as capacity markets and cap-and-floor schemes, is essential to de-risk investment and enable a robust pipeline of bankable projects. Furthermore, the Pledge advocates for streamlined and harmonised permitting processes at both EU and national levels, with clear timelines and accountability for regulatory authorities. Recognising PSH as critical infrastructure in national and EU energy strategies, and ensuring access to funding under the EU Green Deal and related instruments, are also vital. Finally, the Pledge calls for regular assessment and reporting by member states on flexibility needs and storage capacity, with binding targets for the deployment of long-duration storage solutions.
Conclusion
Looking ahead, we anticipate that the Paris Declaration will drive tangible change across the hydropower industry. In practical terms, we expect to see a marked increase in the integration of environmental, social and governance (ESG) principles into project planning, contracting and execution. Project sponsors and financiers are likely to require more robust sustainability assessments and disclosures as a precondition for investment, while host governments may increasingly reference the Declaration in regulatory frameworks and procurement processes. This should result in greater transparency, enhanced stakeholder engagement – particularly with local communities and indigenous peoples – and a higher standard of environmental and social performance across new and existing projects. Ultimately, the Declaration is poised to shift the industry norm from voluntary aspiration to measurable, contractual commitment, fostering a culture of continuous improvement and accountability. If these trends continue, the Paris Declaration could serve as a blueprint for responsible infrastructure development well beyond the hydropower sector. With renewed commitment secured through the Pledge, PSH can help secure Europe’s clean energy future – delivering stability, flexibility and progress towards climate change goals.
With thanks to Anna Pritchard for her contribution to this article.
