Blog by Edo Abraham, Derya Sadak, and Eunice Pereira Ramos, Department of Water Management, Delft University of Technology

As countries in Africa accelerate the development of their renewable energy systems to meet access targets and developmental needs for a reliable modern power system, a critical question looms for national energy planners: where will the grid-scale storage come from? New research from the EPIC Africa project takes on this challenge for Kenya and finds that the country has significant pumped hydro storage potential.

The Storage Gap

Kenya’s electricity system is already one of the most renewable in the world, with nearly 90% of generation coming from clean sources such as hydropower and geothermal. And yet, reliability remains a pressing challenge: blackouts increased from 26 to 48 between 2020 and 2023 [1]. The growing share of variable renewable energy (VRE) now and in future plans places additional pressure on grid stability that short-term battery storage alone cannot resolve. Pumped hydro storage (PHS), currently accounting for over 90% of global grid-scale storage by energy volume [2], offers a domestically resourced, long-duration storage solution. However, PHS deployment remains limited across Sub-Saharan Africa, hindered by high upfront capital costs, spatial complexity, and the general global trend of storage policy and planning behind, as reported by IEA [2]. This motivates country-specific planning frameworks to explore PHS potential in their clean energy transitions, taking into account local hydrological, environmental, and socio-economic needs.

A nexus approach for repurposing existing water bodies for energy storage

Although PHS is a mature technology that is cost-effective compared to other options (e.g., in terms of Kenyan Shillings per MWh of storage or MW of capacity), like hydropower, it is a capital-intensive infrastructure. Rather than starting from scratch with the construction of a new pair of reservoirs, our study investigates the repurposing of existing water bodies such as hydropower dams, natural lakes, and water storage reservoirs as components of paired PHS systems. This approach can significantly reduce capital costs while leveraging existing environmental assessments and grid connections. However, the economic case for existing water bodies cannot be evaluated on the cost of energy storage alone; water availability, land use, proximity to grid infrastructure and protected biodiversity must also be considered to assess which sites are genuinely feasible. To systematically capture these interactions, we based our analysis on the CLEWs (Climate, Land, Energy, and Water Systems) framework.

Within this framework, a GIS-based site-search screens all sufficiently large water bodies across Kenya’s five major basins, identifying candidate reservoir pairs in two terrain typologies: flat-area enclosed reservoirs (Type-I) and mountainous dry-gully reservoirs (Type-II). For each candidate site, the analysis quantifies storage capacity, capital cost, land footprint, water requirements, and proximity to roads, transmission lines, and Kenya’s most economically viable wind and solar zones.