The European energy crisis has placed greater focus on the industrial heating transition. After all, there is an enormous potential for savings, as approximately two-thirds of the total energy consumption in industrial processes is accounted for by process heat in production. Especially in view of high gas prices and political requirements for decarbonization, it is crucial for companies to drive the transformation of their supply to renewable energy and electrify their process heat. Meanwhile, technologies such as thermal energy storage play an important role for companies in making the switch to sustainable production economically profitable.
How does thermal energy storage work?
Thermal energy storage systems include both heat and cold storage systems. In thermal storage, energy is supplied to the storage medium in the form of heat during the charging process, and released again during the discharging process. The most commonly used systems include sensible heat storage, latent heat storage and thermochemical heat storage. These differ according to storage duration, temperature as well as the applied principle of storage.
Sensitive heat storage
In so-called sensible heat storage, the temperature of a material – a solid or a liquid, depending on the system – is raised to store thermal energy. Typical storage materials include water, thermal oil, concrete, sandstone, bricks, or molten salts. The potential storage period depends on the storage materials used. Sensible thermal storage is the most established and cost-effective method for thermal energy storage.
Latent heat storage
In latent heat storage systems, thermal energy is stored with the aid of a phase changing material. When these materials change phase (from solid to liquid, for example), they have to absorb energy. This energy, which has been added to the material, remains bound in the material as so-called latent energy. Typical phase change materials include ice, kerosene, fatty acid, sugar alcohol, salt hydrates, inorganic salts and metals. Latent heat storage materials can store energy over a long period of time without major losses. So far, these stores have seldomly been used in an industrial context.
Thermochemical heat accumulators
Thermochemical heat storage systems use the reversible gas-solid reaction. The energy is stored in an endothermic reaction instead of a temperature rise, which offers the advantage of low storage loss. Two types of thermochemical storage technologies can be distinguished: thermochemical reactions and sorption processes. Their advantage is the very high energy storage density and low storage losses.
Example of thermal energy storage: The thermal battery
The ThermalBattery™ by ENERGYNEST – a solid-state high-temperature thermal energy storage system – is a sensitive heat storage system. Thermal energy is transferred to the ThermalBattery™ by means of a heat transfer fluid – usually thermal oil, water or steam. Heat is transferred to the HEATCRETE® solid-state storage material via cast-in U-shaped heat exchange tubes made of carbon steel. The energy is stored with minimal heat loss until it is needed. The transfer takes place exclusively via the steel tubes of the heat exchanger. The maximum temperature for charging is approx. 400°C.
Advantages of thermal energy storage for industrial purposes
The ability to store energy and utilize it when needed at a later date is essential for an affordable energy transition. Thermal energy storage offers the industry a number of advantages through its various applications.
Achieving energy security: rapid implementation
The Russian war of aggression has clearly shown the consequences that a strong dependence on gas can have for companies. Energy security is therefore an important goal for the industrial sector in particular. The use of thermal energy storage systems is a quickly implementable solution to this problem, as they are easy to install and in some production processes, such as the switch from gas-fired boilers to e-boilers, no major structural changes are required for their implementation.
Storing surplus energy - and thus reducing costs
By electrifying their production processes and storing low-cost electricity at off-peak times for later use, companies can protect against price volatility as well as market price risks, fluctuating gas prices, CO2 compensation costs, and grid balancing charges.
Reducing emissions by increasing energy efficiency
The energy efficiency of production plants can be significantly increased by using surplus process heat. This not only enables valuable cost savings, but also reduces emissions. An important factor for companies to meet both their own and political targets for decarbonization.
Storing electricity as heat: Increase share of renewable energies
By using thermal energy storage, fluctuating availability of wind and solar energy can be decoupled from the actual time of use by storing it as thermal energy. In this way, companies can increase the share of renewable energies – and at the same time guarantee the security of their production processes. An important step on the way to independence from fossil fuels.
Thermal energy storage is no longer a research and development project. It is ready for commercial deployment to support the energy transition. Thermal energy storage technologies like ENERGYNEST’s ThermalBattery™ are market-ready, proven and available.
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