System integration of renewable energy: More flexibility in the electricity market through thermal energy storage systems

Systemintegration erneuerbarer Energien: Wind- und Solarenergie

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The energy supply in Europe needs to become climate-neutral and at the same time make us independent of the import of fossil fuels, power and heating. To achieve this goal, the expansion of wind and solar energy must be vigorously pursued. In addition, a fundamental restructuring of the electricity grids is needed so that the reliable and economically efficient system integration of renewable energies can be guaranteed. Flexibility is becoming the decisive factor in successfully integrating volatile energy sources. Energy storage systems can help to balance out the temporary imbalance between supply and demand – and thus make the energy market more secure and flexible.

Challenges due to system integration of renewable energy

The ever-increasing share of renewable energies poses new challenges for the electricity grids in order to continue to guarantee security of supply as well as price stability. Electricity generation from wind and solar energy exhibits both weather-related and daily and seasonal natural fluctuations. Therefore, a flexible energy supply system is needed that can react to the volatile supply and demand situation.


But the problem is not only a potentially too low supply of energy from renewable sources, but also a too low demand with a high amount of produced electricity leads to problems. For example, several thousand GW hours of electricity cannot be fed into the grid each year because the grid is unable to absorb it.

Increasing the flexibility of the energy market through thermal energy storage systems

Flexibility is therefore central to the development of an energy supply system that is fed with renewable energy sources. In the case of high electricity demand and simultaneously low production of wind or solar energy, in addition to flexible producers and electricity imports, flexible consumers are also needed that can specifically control the amount of energy and the time of energy consumption. In the opposite case, too – low electricity demand and high production at the same time – the possibility of flexible consumption is crucial in addition to electricity exports. Thermal energy storage systems such as the ThermalBattery™ from ENERGYNEST can support both the producer and the consumer in achieving this flexibility.

Heat storage brings more flexibility: power-to-heat

On the corporate side, especially in the energy-intensive industries, the use of thermal storage systems brings much-needed additional flexibility as well. Thermal energy storage in combination with, for example, heat pumps or electric boilers (“power-to-heat systems”) make it possible to replace gas as well as other fossil fuels with renewable electricity and thus reliably provide the required process heat. In addition, by using energy storage systems, companies can protect themselves from price fluctuations and market price risks by buying electricity cheaply during off-peak periods and using it later when needed.


Power-to-heat systems, including thermal storage, play an important role as an alternative to natural gas, on the one hand, by replacing gas-fired power plants as a flexibility option on the electricity market and gas boilers as the primary source of process heat in the industrial sector. In this way, they not only provide the important flexibility in the electricity market, but also decarbonise energy-intensive industrial processes. In addition, thermal electricity producers such as waste incineration plants, CHP plants, combined cycle plants or biomass plants can optimise their electricity yields by using thermal energy storage.

Integration of renewable energies in the supply of companies

Thermal energy storage also makes it possible for companies to integrate their own renewable energy generation systems into their production processes. For example, the use of ThermalBattery™ allows Avery Dennison Performance Tapes, a Belgian manufacturer of pressure-sensitive adhesive products, to switch heat generation for its production facilities from natural gas to concentrated solar thermal (CST). The ability to store excess energy during the day and use it at night thus contributes to the decarbonisation of production and also makes the company independent of fluctuating electricity market prices and availability.

Greater flexibility for the energy supply in companies through "Demand Side Management"

The so-called “Demand Side Management” (DSM) or also “Demand Side Response” (DSR) can also contribute to a more flexible energy supply system with a high share of renewable energies. Companies are able to specifically control the amount of energy they need and when they need it. This load control on the consumer side helps to stabilise the electricity grids. The advantage for companies: They can use electricity when it is available at low cost. When electricity prices rise, they can in turn slow down their production or use previously stored energy. Thermal energy storage contributes here once again to being able to use the volatile renewable energies as efficiently as possible while at the same time ensuring the security of supply of industrial processes.

Policy requirements: Promotion of technologies to make the electricity market more flexible

To promote the successful system integration of renewable energies, political incentives for flexible electricity consumption are needed. One possibility would be grid fees that are low in times of electricity surpluses and low grid bottlenecks. In Germany, for example, this is not yet the case: the calculation of grid fees still gives consumers with constant electricity consumption an advantage over flexible consumers who ramp up their consumption at certain times (e.g. when there is a power surplus and low grid load). The promotion of energy storage technologies must also be brought into the political focus, as they represent an important element as part of a flexible energy supply in order to advance the successful system integration of renewable energies.

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