Heat 2 Power:
New Thermo Storage Technology []

Advantages of the New thermal storage technology

Optimal material combination

The heat storage mass combines steel pipes and mineral fillers in a targeted manner.

• Sustainability: This material selection is cost-effective, resource-efficient, environmentally friendly, and enables virtually unlimited cycle stability. The storage unit has a robust, durable design.
• Process engineering efficiency: High energy storage density, low reproducible pressure drop during flow, short response times for heat exchange, targeted homogeneous heat distribution, high-pressure operation with high energy density possible.
• Optimal operation: Defined flow paths and heat transfer routes; no high-temperature filters; separate circuits for charging and discharging; full process control.

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• The minimized void volumes result in a high volumetric heat storage density. Compared to conventional storage systems, the heat storage density is 4–8 times higher than that of lava rock.
• Dead zones are eliminated because the gas no longer follows the path of least resistance.
• A migrating "heat front" is virtually impossible – instead, a homogeneous temperature distribution prevails within the module – directly measurable and usable as a key parameter for control. The control system always "knows" which modules need to be activated for loading and unloading.
• Defined flow paths allow for precise design and result in reproducible flow parameters.
• No dust in the air circuit (no abrasion of the storage mass as with bulk materials), therefore no high-temperature filters are required.
• The combination of steel pipes and minerals allows for separate circuits for loading and unloading, as well as different media (e.g., nitrogen, thermal oil, flue gases, steam).

Separate circuits for charging and discharging current

• Simultaneous charging and discharging via separate piping systems: This is a unique selling point that is particularly relevant for medium-term storage cycles – for example, during periods of low wind and solar power generation.
• Continuous Operation: Unlike conventional storage systems, charging does not need to be stopped to allow discharging. This allows a downstream heat engine to operate continuously, even if the power input fluctuates.
• Integrated Heat Recovery: The residual heat after energy is delivered to a downstream heat engine is not waste heat, but is fed back into the storage system using the counterflow principle.

Technical details: Time course of the heat input

The following graphic shows the temporal profile of a fluctuating heat input. Approximately 40% of the time, the temperature is below the minimum usable temperature (“T_min”) for reconversion into electricity. While conventional storage systems cannot utilize energy during such phases, the new Heat2Power-Technology allows for continuous discharge by diverting the energy to other modules. This also stores low-temperature heat for later recovery – a crucial advantage over previous systems.

Technical details: Temperature ranges and residual heat utilization

Another unique feature is the use of residual heat to preheat the discharge current. Modules with lower temperatures are used for preheating before the hotter areas are utilized. This increases the temperature difference delta (ΔT) between the inlet and outlet temperatures.
Result: higher efficiency and a longer extraction time for the stored heat. This intelligent use of temperature ranges significantly increases the efficiency of the regeneration process.

Modular design with flexible interconnection

The new thermal storage technology has a modular design and allows for flexible interconnection of the individual modules. This enables the efficient handling of widely varying feed-in power outputs – such as peak power from wind energy.
Heat can be extracted precisely where the desired temperature is present. This allows for continuous reconversion to electricity even with fluctuating feed-in and increases the overall system efficiency.

• Flexibility: Modules can be connected in series, parallel, or sequentially – depending on the operating requirements.
• Efficiency: Stepwise temperature changes between charging and discharging increase the usable temperature range and the efficiency of the heat exchange.
• Compactness: Less unnecessarily circulating gas, reduced equipment requirements, and smaller dimensions for the same current output.
• Scalability: Storage units can be expanded as needed.

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• Serial connection allows for counterflow heat exchange between charging and discharging → higher temperature differences and more efficient heat exchange.
• The stepwise temperature change from module to module maximizes the heat exchange between the gas and the storage unit, so that very little residual heat remains in the gas.
• Thanks to the flexible connection, the need to mix in cold air to reach the target temperature is eliminated – the modules deliver the desired temperature directly.
• Large quantities of unnecessarily circulating gas are avoided → reduced equipment requirements (fans, heat exchangers).
• A larger proportion of the stored heat is used for power generation.

Proportion of stored heat for reconversion to electricity

Setup and integration

The New Thermal Storage Technology allows for decentralized installation directly at the energy source, e.g., a wind turbine. This eliminates the need for additional grid expansion and facilitates integration into existing systems.
An optimal configuration for the energy transition involves feeding power up to the annual average output into the grid, while surpluses are stored in the thermal storage unit and converted back into electricity as needed.

• Decentralized Integration: Installation directly at renewable energy generation sites; no additional grid expansion required.
• Grid Relief: Surpluses above average output are stored; base load is continuously supplemented.
• Backup Relief: Conventional power plants operate at a lower, more consistent level; no peak load design is necessary.
• Flexibility: Thermal engines can also be operated with biofuels if required.

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• When renewable energy generation is below the defined base load, the stored heat is used to operate a heat engine.
• Optionally, the heat engine can be operated with biofuels such as bio-LNG or hydrogen (H₂) for short periods when no renewable energy is being generated and the storage tank is empty.
• The heat engine only needs to be designed for base load (approx. 15–25% of the rated output of a wind turbine).
• Example: The base load of a 15 MW wind turbine is approximately 2300–3000 kW.
• Separate piping systems for loading and unloading also allow the use of various media such as nitrogen, thermal oil, flue gases, or steam.
• Elimination of many additional components → reduced complexity.
• Flexible interconnection of the modules (series, parallel, sequential) eliminates the need for cold air mixing.
• Minimalist layout without numerous pumps, heat exchangers, or compressors; maximum temperature differentials are possible even without the Rankine cycle.

Efficiency

The New Thermal Storage Technology achieves a significantly higher efficiency than conventional systems. While traditional storage systems convert only 20–30% of the input heat back into electricity, the new thermal storage system achieves 70–90%. This means that significantly more usable electrical energy is generated from the same amount of heat.

• Higher energy recovery efficiency: Up to 3 times the efficiency compared to previous high-temperature storage systems.
• Faster start-up: Smaller modules reach the required operating temperature more quickly.
• Continuous efficiency: Even with fluctuating power input, energy recovery remains stable.
• Compact design: Less heat is required to generate the same amount of electricity.

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• Commercially available storage systems often do not define their "storage efficiency" as the ratio of recovered electrical work to input heat.
• With conventional storage systems, efficiency decreases continuously during charging because the temperatures of the charging current and the storage mass approach each other → more residual heat is lost.
• The new thermal storage system avoids this effect through staged temperature control and flexible module interconnection.
• Diagrams of the temperature over time show that the new storage system is ready for operation more quickly with the same amount of heat.
• Even with intermittent operation, the heat engine remains continuously operational, even if only lower temperatures are temporarily supplied.
• Discharge begins early because the first modules are charged quickly; this extends the extraction time and makes more heat usable.

Charging and discharging dynamics

Overall, this allows for highly dynamic charging and discharging of the storage system. Unlike previous storage systems, it can be continuously discharged, and with greater efficiency.

In comparison to previous high-temperature heat storage systems, the New Thermal Storage System can therefore

• Smaller dimensions to enable the generation of the same amount of electrical energy.
• Generate the same amount of electrical current with less heat input.
• Even when operating at a lower temperature level, achieve higher performance than previous thermal storage systems.

How much thermal storage capacity is needed?

Is the new thermal storage technology superior to previous storage systems?

What can  the competing products do?