Energy transition and storage needs
Energy has always been the foundation of human development. Today, the global energy transition faces a new challenge: electricity from solar and wind power must not only be generated, but also reliably stored.
Energy Transition [
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The need for energy storage
Renewable energy sources are weather-dependent and fluctuate significantly. Without storage, several key problems arise:
- Volatility: Electricity from wind and sun fluctuates greatly, supply gaps occur during periods of calm or cloud cover.
- Periods of low wind and solar output: Without backup power plants or storage, guaranteed power is lacking.
- Network stability: The elimination of large generators leads to frequency and voltage fluctuations.
- Overproduction: Excess electricity must be curtailed or exported at a high price.
Conclusion 1: Scenarios in case of electricity surplus
| Scenario | Consequence |
|---|---|
| Extreme Case 1 | Without storage, large portions of renewable generation must be curtailed, leading to wasted energy and high costs. |
| Extreme Case 2 | If curtailment is not allowed, the share of renewables remains limited without storage, requiring significant backup capacity. |
| Compromise | A mix of storage, demand-side management, limited curtailment, and conversion technologies (e.g. power-to-gas) offers the most viable solution. |
Conclusion 2: Scenarios during periods of low wind and solar activity
| Scenario | Consequence |
|---|---|
| Extreme Case 1 | Backup power plants compensate for the entire shortfall, requiring large amounts of secured capacity. |
| Extreme Case 2 | Storage systems cover the entire gap, demanding extremely high storage volumes and continuous output. |
| Compromise | A combination of flexible generation, demand-side management, and storage reduces dependence on fossil fuels and ensures reliability. |
Comparison of technologies and measures
Pumped hydro storage
Capacity: Medium-scale storage, widely used in many countries
Efficiency: 70–80%
Costs: Low operating costs
Challenge: Limited new sites, environmental impact
Batteries
Capacity: Short- to medium-term storage, rapidly expanding
Efficiency: ~90%
Costs: High investment costs, raw material constraints
Challenge: Limited lifespan, recycling issues
Power-to-gas
Capacity: Potential for large-scale seasonal storage
Efficiency: 20–30%
Costs: High conversion losses
Challenge: Infrastructure needs, low efficiency
Flywheels
Capacity: Short-term stabilization only
Efficiency: High instantaneous efficiency
Costs: Moderate
Challenge: Not suitable for long-term storage, standby losses
System flexibility
Capacity: Demand-side management, grid expansion
Efficiency: Varies
Costs: Moderate
Challenge: Helps balance peaks, but cannot fully replace storage
Curtailment
Capacity: Reducing renewable output during surplus
Efficiency: 0% (lost energy)
Costs: High economic losses
Challenge: Inefficient, contradicts climate goals
What kind of energy storage do we really need?
The energy transition is not just about long-term storage for entire seasons, but above all about medium-term storage that balances fluctuations over days and weeks. The biggest challenges arise not between July and January, but between Monday and Sunday, or between afternoon and morning. Storage facilities must therefore be sized to ensure average output and smooth peaks – not just extreme events lasting for months.
The golden mean
The following graphics make it clear that there is no need for high capacities of long-term storage, but for medium-term storage:
Seasonal and weekly variations in renewable electricity generation and demand
Daily fluctuations in renewable generation and consumption (example period)
 Hydropower
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 Photovoltaics
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 Bio mass
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 Wind Onshore
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 Wind Offshore
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 Load history
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The horizontal dashed lines show from top to bottom:
1. Maximum power, 2. Average power, 3. Base load (secured minimum power).
1. Maximum power, 2. Average power, 3. Base load (secured minimum power).
(https://www.agora-energiewende.de)
Conclusion 3: Insights from the illustrations
- Seasonal patterns: Solar generation is strongest in summer, while wind dominates in winter.
- Short-term fluctuations: The largest variations occur on a daily and weekly basis, not seasonally.
- Demand rhythms: Electricity demand also shows clear daily and weekly cycles, often stronger than seasonal differences.
- Partial overlap: Solar peaks often coincide with high demand, but gaps remain that storage must fill.
- Storage needs: Systems mainly need to bridge days or weeks, not entire seasons.
International Plans for the Energy Transition
England (UK):
The United Kingdom aims to achieve net-zero greenhouse gas emissions by 2050. Current plans include expanding renewable energy to provide a significant share of electricity by 2030, with strong growth in offshore wind, solar, and battery storage.
The UK relies on a mix of flexible power plants, interconnectors with other countries, demand-side response, and energy storage to balance the grid during periods of low renewable output. Investments are also directed toward hydrogen and carbon capture technologies.
Switzerland:
Switzerland plans to phase out nuclear power by the mid-2030s and increase the share of renewable energy in its electricity mix to at least 50% by 2035. Hydropower already provides the majority of electricity generation.
Switzerland relies on its large hydropower capacity and interconnectors with neighboring countries to balance the grid. Expansion of solar and wind power, as well as investments in batteries and power-to-gas, are part of the national strategy.
USA:
The United States targets a carbon-free electricity sector by 2035 and net-zero greenhouse gas emissions by 2050. Wind and solar have grown rapidly and already surpass coal in electricity generation.
The U.S. strategy combines flexible power plants, transmission expansion, demand-side management, and energy storage. Large-scale projects in hydrogen, carbon capture, and pumped storage are also being developed.
Sweden:
Sweden aims for 100% renewable electricity production by 2040 and net-zero greenhouse gas emissions by 2045. Hydropower and nuclear power provide a strong base, complemented by growing wind and solar capacity.
Sweden relies on interconnectors with neighboring countries and invests in batteries and power-to-gas to balance the grid during periods of low renewable output.
Austria:
Austria plans to achieve 100% renewable electricity production by 2030 and net-zero emissions by 2040. Hydropower already provides the majority of electricity, supported by wind and solar expansion.
Austria leverages its strong hydropower base and cross-border connections, while investing in new storage technologies and demand-side flexibility to ensure reliability.
France:
France aims to reduce its reliance on nuclear power from around 70% to 50% by 2035, while increasing the share of renewable energy to 40% by 2030.
The country relies on nuclear and hydropower for stability, and is expanding solar and wind capacity. France also invests in hydrogen and carbon capture to support its energy transition.
Norway:
Norway targets net-zero greenhouse gas emissions by 2050. Over 90% of its electricity already comes from hydropower, giving it one of the cleanest electricity mixes worldwide.
Norway plans to expand wind and solar capacity, while investing in batteries and hydrogen. Strong interconnectors with neighboring countries help balance supply during periods of low renewable output.
Power to Gas is not a one-size-fits-all solution
The following considerations show why the widely favored methanation is unsuitable for intermediate storage and smoothing of energy on a large scale.
- The use of excess or peak power for producing methane leads to the effect that these plants have high downtimes and are not worth investing in. However, they would still have to be designed for large outputs or the peaks in electricity generation would have to be discarded. You need locations with a constant amount of wind or a lot of sun.
- The multiple conversion in the power-to-gas process also leads to high losses in the electricity originally used. An overall efficiency of less than 30% remains. It is often suggested that the poor levels of efficiency in the "Power-To-Gas-To-Power" process can be improved by using waste heat. It is ignored that this waste heat is not available for a large part of the year because these plants are idle for lack of excess wind.
Loss chain in methanation and hydrogen
|
Renewable energy |
100% |
|
|
| transformer and rectifier (η = 95%) | |
|
|
95% |
| electrolysis (η = ca. 75%) | |
|
|
70 ... 72% |
| methanation (η = 80%) | |
|
|
56 ... 60% |
| compressor, storage (η = 98%) | |
|
|
55 ... 58% |
| Transport (η = 99%) | |
|
|
55 ... 57% |
|
| ||||||
Conclusion 4: Use only in exceptional cases
Power-to-gas – whether methanization or hydrogen – is not suitable as a standard solution for the energy transition. The efficiency of the process drops below 30%, even with waste heat recovery. Furthermore, hydrogen is too valuable as a raw material for industry and transportation to be wasted on short-term balancing of electricity fluctuations. Its use only makes sense in exceptional cases – for example, during prolonged periods of low wind and solar power generation or at locations with consistently high renewable energy production. For everyday balancing, however, we need storage facilities that can bridge several days and directly store electricity.
Limitations of traditional backup options
In addition to the technical losses of classic storage technologies, there are also practical obstacles: Neither new gas-fired power plants nor a massive expansion of the grid are realistically feasible – the material and human resources are lacking, and copper as a key raw material is becoming increasingly scarce.
Hydrogen: limited availability
Green hydrogen is considered a promising energy source, but is currently only available in very small quantities. Production via electrolysis is energy-intensive and costly, and large-scale infrastructure is still lacking. Import strategies remain uncertain in the long term. Therefore, hydrogen is not a realistic backup option for the next few decades.
Gas-fired power plants: lack of resources
New gas-fired power plants require significant investment, long construction times, and specialized materials. If used only as backup capacity, they are often economically unprofitable. For this reason, relying on new fossil-based plants is not a sustainable option for the energy transition.
Electricity imports: limited reliability
Cross-border electricity imports can help balance supply, but during widespread shortages neighboring countries often face similar challenges. Transmission capacities are limited, and imported electricity is particularly expensive during times of scarcity. Dependence on foreign supplies increases political and economic risks.
Raw material constraints
Expanding grids and building new infrastructure requires critical materials such as copper, lithium, cobalt, and nickel. These resources are limited and subject to global supply risks. Delays in mining and production make short-term relief unlikely, creating bottlenecks for large-scale expansion.
Grid stability challenges
The reduction of large conventional power plants makes frequency and voltage control more difficult. Traditional backup options cannot permanently guarantee stability. Without suitable storage technologies, the risk of grid disturbances increases, potentially leading to widespread outages.
A recent example is the Iberian blackout of April 2025, when Spain and Portugal experienced a cascading grid failure that left millions without electricity for hours. The incident highlighted how vulnerable modern power systems can be when renewable generation fluctuates and backup solutions are insufficient.
Diesel generators: inefficient and polluting
In many regions, diesel generators are still widely used as backup power sources. They are inefficient, costly to operate, and highly polluting. Reliance on diesel slows down the energy transition and increases greenhouse gas emissions, especially in developing countries and island grids.
Extreme weather risks
Traditional backup systems such as gas or coal plants are vulnerable to extreme weather events. Heatwaves, droughts, and floods can reduce cooling capacity, damage infrastructure, or disrupt fuel supply. Recent incidents in the United States and Australia have shown that climate extremes can severely limit the reliability of conventional backup options.
Nuclear energy: high costs and long-term risks
Nuclear power provides low-carbon electricity, but faces significant limitations as a backup option. New plants require extremely high investment and long construction times, often exceeding a decade. While operating costs are relatively low, decommissioning and waste disposal add major financial burdens.
Safety concerns remain due to the potential impact of accidents, and public acceptance is limited. Uranium resources are finite and concentrated in a few countries, raising supply risks. In addition, nuclear technology carries proliferation concerns, as enrichment and reprocessing can be misused for weapons development.
Overall, nuclear energy is not a quick or flexible solution for balancing renewable fluctuations. Its role in the energy transition is constrained by cost, time, safety, and political challenges.
Conclusion 5: The energy transition needs Heat2Power
Current approaches to balancing renewable energy – such as grid expansion, reserve power plants, and curtailment – are costly and often inefficient. Despite massive investments, energy supply remains uncertain, and traditional backup options cannot guarantee long-term stability.
Heat2Power offers a new thermal storage technology that transforms surplus electricity into a reliable energy source. Unlike conventional storage systems, it enables efficient reconversion into electricity, providing security of supply and stabilizing the grid. Without such innovations, the energy transition risks becoming an unfulfilled promise – with Heat2Power, it becomes achievable with manageable effort.
"Power-To-Heat-To-Power":
Thermal storage – the underestimated alternative
The challenges of the energy transition presented here culminate in a new solution: The long-sought alternative to the aforementioned technologies is now available – a special thermal storage system for Power-to-Heat-to-Power.
It differs fundamentally from conventional thermal storage systems because it not only temporarily stores heat but also makes it available for reconversion into electricity in a targeted and efficient manner.
This transforms surplus electricity into a reliable energy source – a novel device and building block for security of supply and grid stability.
The principles of the New Thermo Storage Technology
"If an idea doesn't sound absurd at first, then there's no hope for it" (A. Einstein)
The New Thermo Storage Technology follows the same principle as conventional storage systems, but the configuration of the entire system has been drastically changed. It is based on the following principles:
- Not the highest quality storage material is the starting point of the design and then the system is constructed around it. The overall configuration and functionality is the basis for the storage material to be selected. As a result, only then a suitable storage material is selected and then the dimensions determined.
- Charging and discharging are decoupled and each represents an independently operating system.
- The system can only be optimized thermodynamically and fluidically if it works like a countercurrent heat exchanger.
Features and details of the New Thermo Storage Technology
Contact + request for licenses
- Dipl. Ing. Thomas Seidenschnur
- info@heat2power.com