Energy storage will not replace gas. Germany’s lesson in system security

The latest analysis by Thema Consulting Group indicates that battery storage alone will not be sufficient to fully replace gas power plants in Germany by 2035. The study “The Interplay Between Batteries and Gas in Dunkelflaute Events” shows that without new investments after 2027, the market may face up to 400 hours of extreme price spikes (up to 1000 EUR/MWh) during periods of low renewable generation.

Limitations of battery technology in extreme weather conditions The analysis, based on weather data from the historical year 1985, demonstrates that the effectiveness of energy storage in ensuring security of supply decreases as installed capacity grows. Researchers observed diminishing marginal returns. After surpassing 70 GW of installed battery capacity, additional units no longer provide meaningful improvements to system stability. This is due to the fact that typical discharge durations (the model assumed a mix of 2-, 4-, and 6‑hour batteries) are insufficient to cover multi‑day wind and solar droughts known as Dunkelflaute.

For comparison, an investment in 20 GW of new gas capacity could reduce the number of hours with extreme prices from 400 to just 100. Achieving a similar effect using batteries alone would require installing as much as 90 GW of capacity, and even then around 200 hours of unstable prices would remain. For storage to realistically compete with the flexibility of gas in this area, its operating duration would need to be drastically extended beyond current market standards.

Synergy of gas and storage as the optimal 2035 model

Although gas remains essential, its role in the system will undergo transformation. According to Thema Consulting’s calculations, the optimal solution for eliminating price spikes entirely is a combination of 30 GW of new gas capacity and at least 50 GW of energy storage. In such a configuration:

• Gas power plants would operate infrequently, mainly during periods of capacity shortages, achieving a utilization rate of only 8–14%.
• Installing 90 GW of storage alongside 30 GW of gas would reduce natural gas consumption by 14 TWh annually, as batteries would take over part of the peak load.
• Modern gas units in Germany could displace older, more emission‑intensive coal plants in neighboring countries.
• The impact of storage on decarbonization is significant. Each installed megawatt‑hour of capacity could translate into a reduction of approximately 140 to 200 tons of CO₂, which at a scale of 90 GW yields total savings of around 10 million tons of CO₂ per year.

Analysts highlight a paradoxical relationship: during Dunkelflaute periods, gas power plants will partially be used to charge battery storage so that the batteries can support the grid during the most challenging moments. This means that the two technologies should not be viewed as competitors but rather as an inseparable, balanced mix necessary to carry out the energy transition without exposing the economy to drastic energy costs.