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Strategic Reframing of Seasonal Energy Storage

Imagine a farmer who sows his fields, nurtures the crops through months of hard work, then — during a particularly good harvest — simply dumps the surplus wheat off a cliff into the sea. How would you describe such behavior? Wasteful? Irrational? Perhaps even absurd? For in all his strategy he neglected to build a barn to store his harvest.

Yet this is precisely how modern energy systems manage the output of solar and wind power. At times of peak generation — when the sun shines brightly and the wind blows steadily — vast amounts of electricity are simply curtailed. Not stored. Not redistributed. Just discarded.

And yet, despite this massive and recurring waste, many self-declared experts continue to call for even more installed capacity as a supposed remedy — without addressing the lack of storage or systemic flexibility. The result is a paradox: more production leads to more curtailment. The system scales up its waste alongside its capacity.

Despite the large-scale expansion of solar and wind capacity, more and more electricity is being curtailed each year. This is not due to a lack of generation, but a lack of seasonal storage and grid flexibility. On sunny and windy days, the grid frequently hits its capacity limits, forcing operators to shut down renewable sources — even as this very electricity will be urgently needed during the dark, windless months. One striking example is Gansu province in China, where over 50% of the installed 10 GW wind capacity electricity is curtailed. However, this wind power plant is to be expanded to 20 GW.

While farmers might waste their harvest once or twice in a decade due to unforeseen disasters, this curtailment of energy happens dozens or even hundreds of times a year. If a farmer were to consistently leave his wheat rotting in the field or throw it off a cliff into the sea, he would be deemed utterly irrational. Yet in energy policy, this practice has become routine.

This mismatch is not a minor issue. According to the AQ2050 study published by TransnetBW, it is structurally embedded in the European power system. The study outlines several key layers of this issue:

  1. Temporal mismatch between generation and demand – Renewable energy often peaks when demand is low.
  2. Lack of long-term storage solutions – Excess energy cannot be retained for use in later seasons.
  3. Insufficient grid capacity – The existing grid infrastructure cannot absorb and distribute peak renewable generation.
  4. Inefficiency in relying solely on capacity expansion – Merely adding more solar and wind systems without systemic reform deepens the curtailment paradox.

Source: AQ2050 Study – TransnetBW (2024)

A year has 8,760 hours. In Central and Northern Europe, roughly 4,700 of these are dark hours during which photovoltaics (PV) provide no output. Between October and February, even during daylight, the sun’s low position and persistent cloud cover lead to minimal PV generation. Throughout the entire year, photovoltaics in this region deliver meaningful power during only 1,000 to 1,100 hours—equivalent to just 11 to 13% of the time. This leaves more than 7,000 hours that must be covered by other sources or seasonal storage.

The same applies to wind energy. Wind turbines deliver energy only when wind speeds exceed about 4 m/s. On average, wind turbines achieve about 2,000 full-load hours per year—less than 25% of the year. Wind lull periods (so-called Dunkelflaute) further reduce the reliability of wind as a base supply.

The core problem, however, is that neither sufficient grid infrastructure nor adequate storage systems currently exist to bridge this gap. Despite technological maturity in generation, the system lacks the backbone needed to retain and redistribute energy across seasons. Moreover, as emphasized in the AQ2050 study, even a large-scale expansion of the power grid would not resolve this issue. Electricity must be consumed at the moment it is generated. When darkness falls or the wind calms, transmission lines fall silent — they do not store energy, they merely distribute it when it's available.

This makes seasonal energy storage not just a technical requirement but a strategic imperative. At present, large volumes of surplus electricity are curtailed and effectively destroyed, even as vast fossil fuel infrastructure lies idle—waiting for peak winter demand. The AQ2050 study highlights this paradox but also clarifies that neither grid expansion nor hydrogen conversion can resolve the underlying mismatch. Meanwhile, the rigid gas network remains mostly underutilized during spring and summer months, although it could serve as a seasonal buffer — either by directly absorbing surplus energy in the form of compressed gas or by enabling mobile gas supply to areas of need.

To understand how such a pipe-based storage system works in practice: Surplus electricity—usually from solar or wind—is used to power electric compressors. These compressors extract methane (CH₄) from nearby gas networks and compress it into steel pipes at 250 bar. In doing so, both the chemical energy of the gas (10 kWh/m³) and the mechanical pressure energy are stored. This process effectively converts otherwise wasted electricity into two new usable forms of energy—while utilizing existing infrastructure from the pipeline industry.

Forward-Thinking: High-Density Pipe Storage

Forward-thinking modular high-pressure pipe storage system offers a solution to this challenge. Using serially connected steel pipes (e.g., Nord Stream 2 specification: Ø 1300 mm, length 18 m), the system enables the storage of compressed gas (e.g., CH₄ or biogas) at 250 bar, with the capability of returning the stored energy flexibly and locally during the winter months. This structure bypasses the need for costly net expansion and can be implemented at decommissioned power plant sites, industrial zones, offshore, or even maritime applications.

The gas required for this purpose is extracted in spring and summer, when the gas network is not fully utilized, and stored in the pipes under high pressure. Alternatively, it is fed directly from mobile gas tankers into the pipe storage system.

In decentralized or mobile applications, the gas can also be extracted from mobile tanks or connected maritime systems. However, gas extraction in offshore environments is only possible if the wind farm is located directly above or near existing gas infrastructure—for example, an active pipeline such as Baltic Pipe, Langeled Pipeline or the planned commissioning of Nord Stream I or II in the future. This is a prerequisite for making such offshore energy storage possible. Gas extraction from platforms such as Troll A or others is also technically feasible.

Alternatively, these storage tubes can be filled with compressed gas from mobile offshore tankers. However, for practical implementation, the proximity of the offshore wind farms to the existing gas infrastructure is crucial, as this ensures the continuous use of electricity that would otherwise be lost.

Energy Calculation Example: "192-Unit Storage Block"

A model setup consisting of 192 steel pipes and 191 U-shaped connectors has a clearly defined and reproducible geometry:

  • Pipe outer diameter: 1300 mm
  • Pipe wall thickness: 30 mm
  • Pipe length: 18 m
  • Internal volume per pipe: precisely 21.75 m³ (based on inner diameter)
  • Total pipe volume (192 units): 4,173.57 m³
  • Connector volume (191 units à 5.95 m³): 1,136.45 m³
  • Total geometric gas volume: 5,310.02 m³
  • Normalized gas volume at 250 bar: 1,327,505.72 m³
  • Gross energy content (methane, 10 kWh/Nm³): 13.28 GWh

This configuration is meant for illustrative purposes. The same system can be scaled up or down to fit different use cases — for instance, 768 pipes for large industrial hubs, just 3 units for mobile applications, or specialized maritime versions integrated into shipborne infrastructure. The geometric assumptions are fixed and conservative, ensuring that every figure remains technically verifiable.

The decisive advantage of this type of energy storage is that the existing energy source – such as natural gas – can be stored at unprecedented energy densities and safely stored in a relatively small space. Accordingly, four such 192-pipe storage facilities would correspond to the total storage capacity of Germany that has been built up over the last 25 years as part of the energy transition.

This is not a concept. It is a scalable, buildable infrastructure alternative that leverages proven materials, idle gas infrastructure, and real-world limitations of current energy systems. Instead of expanding the grid endlessly to chase intermittent supply, we propose shifting to a logic of preservation—like any smart farmer would do.

This paradigm shift in seasonal energy storage has not only been conceptualized but was formally submitted as a patent application on May 27, 2025. It marks a turning point from mere analysis to actionable infrastructure design.

The compressed gas stored in the pipe system is not limited to electricity reconversion. It can be used for heating, mobility, or even hydrogen production via methane reforming. Especially at former coal power plant sites—where grid connections still exist—such installations can be deployed quickly without lengthy permitting processes.

A Paradigm Shift in the Energy Transition

This approach represents more than just an engineering solution—it marks a structural shift in the logic of the energy transition. By replacing the volatile “use-it-or-lose-it” model with a robust “harvest-and-store” principle, seasonal pipe storage introduces the equivalent of an agricultural rethinking into the power sector. It enables control, resilience, and autonomy—qualities the current system lacks.

With the rapid expansion of solar and wind energy capacities across Europe, the limits of the existing infrastructure are becoming increasingly apparent. Year after year, rising feed-in restrictions underscore the system's inability to absorb peak output from renewable energies. A practical example is the Chinese province of Gansu, where more than half of the energy generated from renewable sources has to be curtailed because there are too few power grids and potential consumers in the area.

Instead of continuing down this unsustainable path, seasonal gas storage in pipelines offers a new perspective based on energy independence, scalability, and economic logic. This will allow the planned energy transition to proceed unhindered. Step by step with innovation.

Energy Retrieval and Utilization Pathways

Once the gas has been stored under high pressure in the pipe system, it can be converted back into usable forms of energy based on demand and application:

  1. Electricity generation – The stored gas can be used in existing or new gas turbines and combined heat and power (CHP) plants to generate electricity during peak hours or winter shortages. This makes it ideal for bridging 'Dunkelflaute' periods when neither sun nor wind are available.
  2. Heat production – The gas can also be directly used in decentralized heating systems or district heating networks. Especially in colder months, this allows stored energy to be released efficiently as thermal output.
  3. Reinjection into the gas grid – If needed, the stored gas can be fed back into the national gas infrastructure during high demand periods, helping to stabilize gas prices and reduce dependency on imports.
  4. Industrial and mobility uses – The high-pressure gas can be used directly for industrial furnaces, kilns, or converted into CNG/LNG for trucks, ships, or heavy equipment—particularly in logistics and agriculture.
  5. Hydrogen production – Stored methane (CH₄) can be reformed into hydrogen (H₂) for use in fuel cells, industry, or as a chemical feedstock. This is especially useful if hydrogen infrastructure expands in the future.

    By offering multiple output options, the pipe storage system is not just a buffer—but a strategic reserve of flexible energy, able to respond to market, grid, and weather fluctuations alike.

Comparison with Batteries, Pumped Hydro Storage, and Planned Gas Power Plants

While battery storage systems and pumped hydro power plants play an important role in grid stabilization, they are fundamentally limited in duration, scalability, and cost-efficiency for seasonal applications.

  • Batteries (e.g., lithium-ion) are primarily designed for short-term buffering, typically spanning minutes to a few hours. They offer rapid response but degrade over time and carry a high cost of approximately €300–600 per kWh installed. Moreover, the materials used—such as lithium, cobalt, and nickel—are geopolitically sensitive and environmentally intensive to extract.
  • Pumped storage plants are more cost-effective per kWh (roughly €100–200 per kWh) and provide medium- to long-duration storage, but they require specific topographical conditions (elevation difference + water basin) and involve large-scale environmental interventions. In many parts of Europe, further expansion is no longer feasible due to geographical and ecological constraints.
  • Planned gas-fired power plants are often presented as a flexible backup for renewable energy. However, they rely on fossil fuels or expensive hydrogen derivatives, emit greenhouse gases, and require extensive permitting procedures. New locations must be connected to both gas and electricity grids, which adds complexity, time, and cost. In many cases, environmental and community opposition leads to multi-year delays or project cancellations.

 

By contrast, modular high-pressure pipe storage offers:

  • Months-long storage capability
  • Minimal land use (especially at decommissioned industrial sites)
  • Flexible scalability (from mobile to gigawatt scale)
  • Significantly lower cost per kWh stored (target: < €10/kWh of chemical + pressure energy combined)
  • Full recyclability and CO₂-neutral operation, when powered by surplus renewable electricity
  • Immediate deployment potential using idle infrastructure

This positions the pipe-based gas storage system as the missing seasonal backbone of the renewable transition—a low-cost, high-volume energy reservoir that avoids rare materials, massive earthworks, or fossil dependency.