The ENERGYNEST ThermalBattery™

Powering you into the future: Our ThermalBattery™ technology for thermal energy storage

At the core of all of our energy storage solutions is our modular, scalable ThermalBattery™ technology, a solid-state, high temperature thermal energy storage.


Integrating with customer application and individual processes on site, the ThermalBattery™ plugs into stand-alone systems using thermal oil or steam as heat-transfer fluid to charge and discharge green energy on demand.

How our technology changes heat into green energy

(1) To charge the ThermalBattery™, hot heat transfer fluid (HTF) directly flows through embedded steel pipes from top to bottom, transferring thermal energy to the HEATCRETE®, its core storage material.
(2) Energy is stored with minimal heat loss until it is needed.
(3) During discharge the flow is reversed; cold heat transfer fluid (HTF) flows in at the bottom and exits hot, supplying energy from the top of the ThermalBattery™. With water/steam as HTF the ThermalBattery™ acts as a steam cooler and condenser in charge mode, and as a boiler and superheater in discharge mode, using the same principles of steam generators installed in conventional- and solar thermal power plants.

Operational range of ThermalBattery™

Maximum temperature for charging our battery is around 400°C using conventional carbon steel piping. Economical applications charge between 250°C and 400°C and discharge between 150° to 350°C. Usually, customer solutions range from 5 to 1000 MWh, with charging/discharging durations from several minutes to several hours.
Operational Range of ThermalBattery
Cost effective
Due to the design and material choice, our ThermalBattery™ represents a cost-effective solution to waste heat recovery. Modules are manufactured by our partners offsite and delivered to our customers for easy assembly onsite – all cutting costs and increasing value.
Safe to use
ENERGYNEST modules are designed in adherence to relevant codes and standards and are inherently safe due to their all-welded piping design. They also undergo rigorous testing and certification before delivery to customer sites, and are CE marked.
Easy to install
When arriving onsite, the modules are ready for immediate assembly, significantly reducing construction time and giving customers quicker access to the operational benefits.
Rapid carbon payback

The payback from cutting your carbon footprint with ENERGYNEST solutions is remarkably fast – with an estimated time of 2 months based on current calculations.
That means your decarbonization strategy could soon start paying for itself – or generate even more value

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    Are you interested in ENERGYNEST, or have any questions regarding our thermal energy storage solutions or our applications for your specific industry?


    Don’t hesitate to drop us a line.

    From casting to site: easy transportation via truck or train due to standardized container format

    Charging based on thermal oil system

    Future-ready thermal oil systems are at the heart of our power, solar and waste heat storing solutions. In these systems, thermal oil is used to transfer thermal energy from a sink to the ThermalBattery™, before supplying it back to a sink when needed. When charging, hot thermal oil is pumped from heat sources such as electric heaters, heat exchangers or solar fields by a pump skid, moving through the steel pipes of the ThermalBattery™ from top to bottom. This transfers thermal energy to the storage material. On discharge, the flow of the fluid is reversed. Constant outlet temperature can be provided in both charge and discharge via integrated piping bypass systems with control valves. To balance changes in volume, the system includes an expansion vessel. The type of thermal oil is tailored to the specific needs of the system and customer requirements. The Thermal-Oil-BOP-package including piping, pumps, valves and expansion vessel is usually delivered as ready to install skid.

    Charging based on steam system

    Steam systems are at the heart of our steam storage solutions. During charging, high pressure steam from source (steam grid, turbine or boiler) flows into the system where it condenses in the ThermalBattery™ modules while transferring the heat to the storage material. The condensate is collected in a pressure vessel. During discharge to a medium- or low-pressure sink (turbine, steam grid or production process), the pressure and the corresponding saturation temperature decrease below the temperature of the storage-material, which starts the evaporation process in both the modules and the vessel (flashing). A control valve on top of the vessel controls this dual evaporation process to ensure a stable supply of dry saturated or slightly superheated steam. If required, the evaporation system can be connected in series with a superheater ThermalBattery™ to provide high-temperature superheated steam. Saturated or superheated steam can be provided with constant, stepped or sliding pressure and temperature. The Steam-BOP-package including piping, valves and pressure-vessel can be delivered as ready to install skid.

    Peer-reviewed design

    The design of our system and the results of our ThermalBattery™ pilot have been published in the Journal of Energy Storage as peer reviewed article “Long-term performance results of concrete-based modular thermal energy storage system”

    From production to site assembly: preparation of the steel cassettes before casting and final assembly of the finished modules at YARA's site in Porsgrunn, Norway

    ENERGYNEST put its innovative technology through rigorous testing in our ThermalBattery™ pilot, installed at Masdar, Abu Dhabi. We are currently delivering several pioneering commercial projects for different applications.
    With our strong partner relationships, we seamlessly integrate our ThermalBatteries™ into existing infrastructure. Creative, flexible collaboration with industry leaders makes waste to energy a reality today – not tomorrow.

    Frequently Asked Questions

    How does a ThermalBattery™ work?

    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 cases this is either thermal oil or water/steam. 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).

    What makes ENERGYNEST different to electrochemical batteries?

    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.

    Who is responsible for building the ThermalBattery™ ?

    We offer our customers the most convenient option for their situation, which is typically one of these two:   The Customer brings its own EPC contractor to site, and ENERGYNEST offers site advisory services, to guide them during the construction of the ThermalBattery™.   We are in charge of a turnkey solution, together with one of our international EPC partners.

    How do you assure the quality of your system?

    We only work with ISO 9001:2015 certified suppliers and partners, who provide top-confidence 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.

    What is the lead time for installing a ThermalBattery™?
    (assume: delivery of materials + construction)

    Three months after the closure of the ThermalBattery™ design, key components are ready to be shipped to site. Transport to site duration will very much depend on project´s location: from one week in an European project, to one month, if it is overseas. The construction process duration depends on the size of the storage, but a good reference is three months for a small project, from civil works to cold commissioning, to six months for a bigger project.

    What are the carbon emissions associated with building a ThermalBattery™?

    CO2 emissions are highly context-dependent and vary greatly from project to project. What is certain is that their impact will generally not be significantly greater than that of cement. A conservative overall estimate comes to a total emission of 15 kg per kWh of storage capacity. The GHG intensity of electricity production differs significantly from one Member State to another. However, the average GHG emission intensity of electricity generation in EU is about 250 g/kWh. A rough estimate for recovery of CO2 emissions for a ThermalBattery™ is two to three months. Therefore, regardless of the type of project, the ENERGYNEST ThermalBattery™ will quickly recover its carbon footprint. The ThermalBattery™ is a smart and cost-effective solution for reducing CO2 emissions in heat-intensive industries.

    How do you generate savings and reduce carbon emissions for industrial facilities?

    ENERGYNEST project developers will start by evaluating process data from the facility. This includes analyzing different heat sources and heat sinks, in terms of temperature, pressure, and flow rates. Many industrial facilities have processes that are either intermittent or highly variable in their energy production and consumption. By recovering thermal energy from high-temperature waste heat sources, storing it, and discharging this energy into downstream processes at a later point in time, ENERGYNEST opens up entirely new possibilities for waste heat recovery: Instead of consuming fossil fuels to generate the heat that they need, industries can simply rely on stored thermal energy. The reduction in fossil fuel consumption allows an equivalent reduction in carbon emissions. The ThermalBattery™ effectively grants industrial plant owners optimal management of their energy use.

    What kind of revenue opportunities do you create for independent power producers?

    The ThermalBattery™ is the ultimate flexibility solution for thermal power plants. It can be directly integrated into existing steam cycles, effectively providing a steam storage buffer between the boiler and the turbine. This allows plant operators to run their boiler continuously while boosting or reducing the electric output on demand. Depending on the case, the system reaction time can be less than 7 seconds. This makes the ThermalBattery™ a perfect solution for providing thermal power plants with the flexibility required to respond to primary frequency response. The ThermalBattery™ can thus be designed to provide a short or long response time, depending on what provides most value in electricity markets.

    How much does the ThermalBattery™ cost?

    The material cost for our basic storage modules completely depends on the actual storage capacity and the individual project conditions. This includes the storage medium, the containment of the medium and the means to input and extract heat from the medium. This also needs to take into account local EPC costs which tend to vary significantly from one project to another. The total system cost will therefore vary depending on its size, functionality, subcomponents, and geographic location.

    What kind of temperatures can your ThermalBattery™ handle?

    Our storage material HEATCRETE® has been tested up to 550°C, and is guaranteed to perform as intended up to 450°C.

    How does the ThermalBattery™ withstand the stress from thermal expansion?

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

    How many charging/discharging cycles can your ThermalBattery™ handle?

    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.

    Does the performance of the ThermalBattery™ degrade over time?

    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 50 years.

    How do you minimize technical risk?

    ENERGYNEST designs the Thermal Battery™ to minimize technical risks to ensure the guaranteed performance. Each Thermal Battery™ module is designed and fabricated in accordance to the Pressure Equipment Directive 2014/86/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.

    What are the heat losses over time?

    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.

    What maintenance does the ThermalBattery™ require?

    The ThermalBattery™ requires very low maintenance as there are no moving parts other than a few control valves on the piping interface with the plant.

    How fast can the battery respond?

    The ENERGYNEST ThermalBattery™ can respond very quickly, and can provide anything from short term frequency response (30 min charge/discharge) up to longer cycles over several days.

    How do you measure the performance of the ThermalBattery™?

    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.