Power-to-heat system with thermal energy storage

The system is designed for industrial applications where large amounts of process heat need to be supplied reliably over extended periods. It is typically used in production environments requiring heat in the temperature range of approximately 120°C up to and beyond 300°C.

Typically, a minimum annual heat demand of more than 5 GWh is required, along with sufficient grid connection capacity. As a general guideline, around 1 MW of electrical connection capacity is needed for every 5 GWh of annual heat demand.

The system is particularly well suited to energy-intensive industries with continuous or semi-continuous heat demand.

These include:

• Chemische Industrie
• Papier- und Zellstoffindustrie
• Lebensmittel- und Getränkeindustrie
• Glas- und Baustoffindustrie
• Metall- und Grundstoffindustrie

• Prozesswärme für industrielle Trocknungsprozesse
• Dampferzeugung für Produktionsanlagen
• Thermalölkreisläufe in industriellen Anlagen
• Integration erneuerbarer Stromquellen in die industrielle Wärmeversorgung

Our storage material HEATCRETE® has been tested up to 550°C, and designed to operate reliably up to 390°C.

Yes. The system can store heat while simultaneously supplying it to the process.

The integrated thermal storage is charged while heat is supplied to the process in parallel. This allows fluctuations in electricity availability to be balanced without interrupting continuous production.

This operating mode enables the flexible use of low-cost or renewable electricity for charging the storage, while stored heat is delivered at the same time for industrial applications such as steam generation, drying processes, or thermal oil circuits.

The ThermalBattery™ can be configured for different operating strategies, ranging from fast-response flexibility applications to longer charging and discharging cycles over several hours or days.

The ENERGYNEST power-to-heat system is delivered and integrated up to defined process interfaces. Existing boilers, turbines, or end users remain unchanged parts of the plant.

System availability is ensured through a robust plant design and continuous operational monitoring. The ThermalBattery™ itself contains no moving parts within the storage medium, significantly reducing mechanical wear and minimising potential failure points.

The few critical balance-of-plant components consist of proven, standard industrial equipment such as pumps, valves, and instrumentation. These components are widely used in industrial applications and can be maintained using established service and spare parts concepts.

System operation is continuously monitored via instrumentation and control systems. Key operating parameters such as temperature, pressure, and flow are recorded and analysed in real time. This enables early detection of deviations and timely corrective action before they impact operations.

The system is integrated into existing process control systems, such as DCS or SCADA environments. Through appropriate interfaces, it can communicate with existing control and energy management systems, enabling the exchange of relevant operational data.

On this basis, operating strategies can be aligned with existing load profiles and production requirements. The control system continuously takes process needs into account and ensures that plant stability and process reliability are maintained at all times.

Optimisation of storage operation or market-driven dispatch takes place strictly within defined operating limits. Process requirements and plant stability always take precedence.

Stable process parameters are ensured through a combination of hydraulic system design and control engineering. Bypass and control valves maintain constant outlet temperatures, even when operating conditions within the system change.

Hydraulic decoupling further stabilises temperature and pressure levels in the process. This prevents fluctuations within the energy system from being directly transferred to the production process.

The thermal storage also enables decoupling between the electricity market and production demand. Short-term changes in electricity supply therefore do not directly affect process heat delivery. Control algorithms continuously compensate for any remaining short-term fluctuations.

Existing boilers remain available in parallel and can be used as an additional stability reserve when required.

Yes. The system has a modular design and can be expanded as needed.

Additional ThermalBattery™ modules can be installed at a later stage to increase storage capacity or the amount of heat supplied. Expansions can be aligned with increasing electrification of process heat or changes in the production setup.

The modular architecture typically allows for such extensions without fundamental modifications to the existing system. This enables step-by-step expansion as energy demand or operational requirements evolve.

Electrochemical batteries, such as lithium-ion and lead acid, need electricity to charge, whereas the ENERGYNEST ThermalBattery™ charges with heat. This means that the ThermalBattery™ can be used for applications (such as combined heat and power) which are not physically possible with electrochemical batteries. Moreover, the ThermalBattery™ has a significantly longer lifetime, near-zero performance degradation, in addition to being made of fully recyclable materials. These materials primarily consist of steel and concrete, which are cheap and globally available commodity materials. This is why the system comes at a significantly lower cost than batteries.

The ThermalBattery™ stores energy directly in the form of heat. No additional conversion steps are required.

In hydrogen-based systems, the process is more complex. Electricity is first converted into hydrogen via electrolysis. This is followed by storage, potentially transport, and later use, for example through combustion or reconversion into electricity. Each of these steps introduces additional energy losses.

As a result, thermal storage systems typically achieve significantly higher overall efficiencies when providing industrial heat. Energy is stored and released directly at the required temperature level, without additional conversion chains.

Another key difference lies in infrastructure and permitting. Thermal storage does not require new fuels or dedicated gas infrastructure. Safety and permitting requirements are also generally less complex than for hydrogen-based systems.

• When significantly higher process temperatures are required than can be economically and technically covered within the typical system design range.
• When annual heat demand is below approximately 5 GWh.
• When sufficient grid connection capacity is not available. As a guideline, around 1 MW of electrical connection capacity is required per 5 GWh of annual heat demand.

Energy in form of heat is transferred to the ThermalBattery™ using a heat transfer fluid (HTF). The HTF can in principle be any fluid with adequate heat transfer properties. In most systems, a liquid heat transfer fluid is used, typically thermal oil or a silicone-based fluid. Heat from the HTF is transferred to the solid-state storage material HEATCRETE® via cast in “U-shaped” carbon steel heat exchanger tubes. There is no direct contact between the heat transfer fluid and HEATCRETE®; the heat transfer occurs through the heat exchanger steel tubes only. The thermal storage element design using U-tubes ensures that thermal stresses in the axial direction are minimized. The thermal elements also include a steel casing which has three functions; being a permanent casting form, an external reinforcement reducing the risk of spalling or cracking, and HTF containment (in the very unlikely case of HTF leakage inside the element). When needed, the stored heat is transferred to the process via heat exchangers or steam generators as steam, thermal oil or hot air.

We only work with ISO 9001:2015 certified suppliers and partners, who provide a high level of quality assurance on our products and services. Additionally, we perform 2nd Party Audits, together with certified bodies, and on-site supervision during the critical phases of the construction process.

The storage material is designed to have a similar coefficient of thermal expansion to that of the cast-in carbon steel pipes.

With daily cycling, a ThermalBattery™ would experience less than 20,000 cycles during 50 years operation. Since the stress values are far away from the failure values for concretes, the stress and fatigue pose no operation issues to our ThermalBattery™ system over 10,000 – 20,000 cycles.

The ThermalBattery™ itself does not have any performance degradation during operation, because the system is entirely made of durable concrete and steel, which can tolerate tens of thousands of stress cycles. All materials are operated within bounds that preserve their integrity for up to 25 years.

ENERGYNEST designs the Thermal Battery™ to minimize technical risks to ensure the guaranteed performance. Each Thermal Battery™ module is designed and fabricated in accordance with the Pressure Equipment Directive 2014/68/EU and are individually CE marked. The energy storage material has undergone a large number of tests both in laboratories and operational pilot plants, and the performance is certified by external auditors. Data on the exact performance and demonstrated system performance can be shared on request.

Thermal losses will be less than 2% over 24hrs for large-scale projects. Smaller projects will have somewhat higher losses as the surface-to-volume ratio increases.

The performance of the ThermalBattery™ is based on measurements of the inlet and outlet HTF temperature and mass flow through the system. These parameters allow for accurate performance monitoring. In case of water/steam, the performance is measured based on mass flow of fluid in either liquid form (water) or vapor (steam), combined with temperature and pressure.