The production of renewable energy depends heavily on the availability of sun and wind. Decoupling energy production from consumption by storage is crucial for a global strong expansion of renewable energies.
The HTTES system provides an inexpensive and very efficient way of storing electrical energy from renewables.
We developed three different systems to store energy:
Thermal Battery with ORC / steam process
With this system electricity to electricity efficiencies of 35-45% are possible. The main advantage lies in low investment costs when using established technologies available on the market (waste heat boiler, steam turbine etc.).
With Power to Heat, the heat is stored at a high temperature-level in the HTTES system.
High Temperature Themal Energy Storage
The modular system allows for storage capacities in the range of MWh to GWh with very high thermal power, so that the storage can be fully charged and discharged within a few hours.
The thermal energy in the HTTES is fed back into the grid with a classic steam process or an ORC. (Heat to Power)
With this system, realistic electricity to electricity efficiencies of up to 60-75% are possible. Therefore, this system is ideal for storing surplus electricity. When compared to battery storage, this system has the advantage of significantly lower investment costs and longer service life.
Using a closed Joule process/Brayton cycle (similar to a high-temperature heat pump), electrical energy is converted to thermal energy and stored in a hot and a cold STORASOL-HTTES.
In the hot STORASOL-HTTES, the heat is stored at up to 800 °C for several hours or days.
In the cold STORASOL-HTTES, the heat is stored at up to -100 °C for several hours to days.
By reversing the same closed Joule process/Brayton cycle, the thermal energy from the energy stores (hot and cold HTTES) is converted back into electrical energy and fed into the grid.
With the OPTES-GT battery, renewable energies can be stored at economically attractive conditions. The low CAPEX is due to the simple and robust technical concept. The efficiency is over 40%.
Electrical energy is converted into thermal energy via an open Joule process/Brayton cycle and stored in a hot pressure storage (P-VHTTES).
In the STOARASOL Pressurized Very High Temperature Thermal Energy Storage (P-VHTTES), the heat is stored at up to 1030 °C and pressures of > 6 bar, up to more than 35 bar for several hours to days.
During the discharge process, the waste heat is stored behind the turbine in the warm HTTES storage (approx. 600 °C). This heat is used during the charging process of the P-VHTTES. The electric air heater therefore only has to heat the air from approx. 600 °C to up to 1030 °C. As a result, the current-to-current efficiency can be increased significantly.
By reversing the same open Joule process/Brayton cycle, the thermal energy from the STORASOL-P-VHTTES is converted back into electrical energy and fed into the grid.