OPED by Kenneth Engblom Vice President, Wartsila Energy, Europe and Africa
The limits of storage-only thinking in balancing Africa’s renewable grids: Why a hybrid approach to flexibility will deliver better outcomes than batteries alone
Africa’s energy transition is entering a decisive phase. With some of the world’s best solar and wind resources, the continent is uniquely positioned to leapfrog into a low-cost, renewable-powered future.
But as policymakers and planners accelerate deployment, a critical misconception often skews the debates: that battery energy storage systems alone can provide the flexibility needed to balance high shares of intermittent renewables. This assumption is not only incomplete, but it also risks making Africa’s energy transition more expensive, less reliable, and ultimately slower.
The real question is not whether storage is needed. It clearly is. The question is whether storage alone is sufficient. The answer, increasingly supported by system-level evidence, is no.
Flexibility is not one thing
Power systems do not require a single type of flexibility, but multiple layers of it.
As renewable penetration increases, so does variability. Solar and wind introduce fluctuations on timescales ranging from milliseconds to seasons. Addressing this requires technologies that can respond across all these intervals.
Battery storage is exceptionally well-suited for fast-response services. It delivers sub-second balancing, frequency control, and short-duration energy shifting.
But this is only one part of the flexibility spectrum.
Longer-duration balancing, which can cover evening peaks, multi-day renewable shortfalls, or seasonal variability, requires a different capability: dispatchable, scalable, and cost-efficient power that can run when needed, for as long as needed. This is where flexible engine power plants play a critical role.
Engines power plants provide grid balancing at the minute, daily, and seasonal level, stepping in when neither renewables nor storage can meet demand.
In other words, BESS and ICE are not competing solutions. They are complementary ones.
The cost of over-relying on storage
The belief that storage alone can deliver system flexibility often ignores a fundamental economic reality: storage costs scale with duration.
Short-duration batteries are increasingly cost-effective. But extending storage to cover longer gaps, such as multi-hour evening peaks or prolonged periods of low renewable output, quickly becomes prohibitively expensive.
This is particularly relevant in African contexts, where demand growth is rapid, grids are often weak or underdeveloped, financing costs are high, and reliability constraints are central.
Designing a system around storage alone to cover all flexibility needs means oversizing battery capacity to unusual but critical events. That leads to underutilised assets and higher total system costs.
By contrast, combining storage with flexible engine capacity allows each technology to do what it does best: minimising overall investment while maximising reliability.
This is not theoretical. Highly precise power system modelling across African markets consistently shows that grid configurations featuring the optimal mix of renewables, storage and flexible engines, deliver the lowest total cost of electricity while maintaining stability.
Africa’s reality demands pragmatism
The debate around flexibility is often shaped by perspectives from mature, highly interconnected power systems. But Africa’s starting point is different.
Over 500 million people still lack access to electricity, and many grids operate with weak infrastructure.
In this context, reliability is not a marginal issue, it is foundational.
A system that cannot guarantee power when the sun sets or the wind drops will not support industrialisation, economic growth, or social development. Nor will it attract the investment needed to scale renewables.
Flexible engine capacity provides a practical solution. It can be deployed quickly, scaled modularly, and operated efficiently at partial loads. That makes it uniquely suited to complement intermittent renewables in emerging power systems.
As previous experience in multiple African energy markets has already demonstrated, integrating renewables with flexible gas engines can simultaneously reduce costs and emissions compared to traditional baseload alternatives.
Avoiding a new form of carbon lock-in
A common concern is that investing in engine-based capacity risks locking Africa into fossil fuels.
This concern is understandable but completely outdated.
Modern engine power plants are designed to run on a range of fuels, including natural gas today, and sustainable fuels tomorrow, as green hydrogen, ammonia, or synthetic fuels become mainstream.
This means that engine power plants serve as a bridge, not a barrier, to a zero-carbon future. Rather than locking in emissions, they enable higher renewable penetration today, while remaining compatible with decarbonisation pathways over time.
Rethinking the role of flexibility
The real risk for Africa is not deploying flexible engines. It is failing to deploy enough flexible capacity of any kind.
Some influential narratives, including recent continental outlook reports, acknowledge the importance of storage and gas-to-power but still underestimate the system-wide value of flexible engine technology in enabling high-renewable systems at lowest cost.
This gap in perspective matters. Because if policymakers design systems based on incomplete assumptions about flexibility, they risk building grids that are either too expensive or not resilient enough.
A balanced path forward
Africa does not need to choose between storage and engines.
It needs to combine them intelligently: renewables provide the lowest-cost energy, batteries provide fast, short-duration flexibility, flexible engines provide long-duration, dispatchable capacity.
Together, they form a system that is not only cleaner, but also more affordable and more reliable. The energy transition is not about maximising one technology. It is about optimising the overall system.
For Africa, that means embracing a pragmatic, hybrid approach, one that recognises that flexibility is multi-dimensional, and that no single solution can deliver it alone.
