Hydropower’s Untapped Potential and Looming Pumped‑Storage Surge Signal a Global Comeback

**TL;DR** Hydropower currently supplies 14% of global electricity, and a significant expansion in pumped-storage capacity is underway, positioning it as a key component for future energy stability.

Hydropower, long a foundational energy source, is re-emerging as a critical component in global energy strategies. Its consistent contribution has often been overshadowed by newer renewable technologies like solar and wind, leading International Energy Agency (IEA) Executive Director Fatih Birol to describe it as “the forgotten giant of electricity.”

Global energy markets face volatility, with rising fossil fuel prices and geopolitical shifts underscoring the need for enhanced energy security. Nations are actively diversifying their power portfolios to reduce reliance on singular, volatile sources. In this evolving landscape, hydropower’s proven reliability and flexibility are drawing renewed attention. Many developing economies also possess significant untapped hydro resources, offering pathways to energy access and industrialization.

Hydropower facilities globally generate approximately 4,500 terawatt-hours of electricity annually, accounting for roughly 14% of global power generation. This output broadly matches the combined electricity production from solar and wind power. Crucially, hydropower offers a distinct advantage over some renewables due to its inherent flexibility; plants can rapidly adjust their electricity output to match demand.

This operational agility means hydropower can provide both consistent baseload power and quick-response generation to manage grid fluctuations. Its established technology and potential for refurbishment and upgrades in existing plants offer a robust, low-cost path to increasing clean energy supply.

The expansion of hydropower is increasingly focused on pumped-storage hydro (PSH), a technology functioning as a giant “water battery.” PSH facilities utilize surplus electricity, often from intermittent sources like solar and wind, to pump water from a lower reservoir to a higher one. When electricity demand peaks or renewable output dips, the stored water is released, flowing back through turbines to generate power.

Currently, pumped-storage hydro capacity globally stands near 200 gigawatts (GW), supplying about 90% of all long-duration energy storage solutions worldwide. This capacity is poised for substantial growth, with an additional 570 GW of PSH planned globally. This significant pipeline of projects underscores hydropower’s escalating importance. Its role in integrating more variable renewable energy sources and enhancing grid resilience will be a critical watch point for the global energy transition.