A Q&A with Hunter Johnson on what the IHA's 2026 World Hydropower Outlook means for operators on the ground — from pumped storage hydrology to climate-driven variability.
The International Hydropower Association (IHA) released its 2026 World Hydropower Outlook today: 1,469 GW of installed capacity, 4,495 TWh generated, and pumped storage — what IHA CEO Eddie Rich is calling the "water battery" — crossing 200 GW for the first time. We asked Hunter Johnson, a HydroForecast Technical Account Manager with a background in hydrology and water resource engineering, what it means for operators on the ground.
The headline numbers are big. What stands out to you from an operational standpoint?
Hydropower supplies 14% of global electricity — it's a critical part of energy portfolios around the world, especially given its ability to provide firm dispatchable energy as renewable energies are increasingly adopted. The grid is asking a lot more of hydro right now, this makes me ask if hydro operators can generate more power efficiently by operating their assets more precisely rather than solely relying on new capital projects. Specifically, how can forecasting inflows into hydro assets enable operators to generate hydropower more confidently – increasing their own revenue while also contributing to the stability of their grid? I work with operators managing those decisions every day, and the margin for error is increasingly small as climate trends change and additional regulations are introduced.
The Outlook is bullish on pumped storage. What's the hydrology angle that tends to get missed in that conversation?
It comes down to the distinction between open-loop and closed-loop systems. Closed-loop pumped storage operates between two purpose-built reservoirs with minimal connection to a natural watercourse. But a meaningful share of the 621 GW pipeline is open-loop, where at least one reservoir interacts directly with a river or natural catchment. For those projects, hydrology is central — inflow variability, drought and flood exposure, long-term water availability, to name a few. Reliable streamflow forecasting matters from 'banking' water through the operating life of the asset.
For conventional hydropower — still the bulk of what's running today — the case is even more direct. We explored this dynamic in depth last year: Pumped storage hydropower: A tale of two cities and the role of hydrology →
What's the most important takeaway for an operator reading this report?
The Outlook flags climate-related hydrological variability as one of the key barriers to realizing hydropower's potential — and I think that's right. Severe droughts in 2025 across South and North America, Asia, and Europe exposed real vulnerabilities tied to water availability. That's not a one-off. It's the operating environment going forward.
More capacity, more grid responsibility, more climate volatility. The operational layer has to keep up.
HydroForecast delivers streamflow forecasts powered by theory-guided AI — helping hydropower producers optimize revenue, manage risk, and operate confidently across multiple time horizons. Learn more →
Hunter Johnson is a Technical Account Manager for HydroForecast at Upstream Tech with 5+ years of experience in hydrology and water resource engineering. Read his piece on managing the Pacific Northwest atmospheric rivers →
