Thermal Storage Tank (TST)

Gallery Thermal Storage Tank (TST) 1
Gallery Thermal Storage Tank (TST) 1
February 2021
Headquarters 7327 Steinsel, Luxembourg

Thermal Storage Tank (TST) - Thermal energy storage system based on existing vehicle washer tank to recover heat and to extend cold operation of electrified vehicles.

The main challenge of Electric Vehicles is the short range due to limited battery capacity. This is further aggravated under low temperature, where the battery loses capacity and supplemental heating draws significant electrical energy, reducing range by up to 40%. On the other hand, excess heat produced during operation or charging is usually rejected to the environment. The Thermal Storage Tank (TST) uses the thermal mass of the existing washer tank, carried on every vehicle, as a heat storage device. The heat generated during vehicle operation is stored on-board and released during cold re-start of the vehicle, supplementing auxiliary electric heating. It may also serve as a heat sink during thermal peaks, for example in fast charging mode. Washer tank sizes are increasing due to the additional cleaning needs for driver assistance devices. In summary, while the electrical powertrain recuperates kinetic energy, the TST recuperates thermal energy.

Key features

  • A 10 ltr tank can store up to 1 kWh of thermal energy, equivalent of 5.5 km of electrical range in city mode, which can be used for warming of the passenger cabin or for windscreen de-icing. The benefits increase with lower temperature, in contrary to bat
  • A water mass allows to absorb heat peaks and preserve battery and other components' life. During ultra fast charge, a full 10 liter tank may adsorb 5 kW of heat during 12 minutes, assisting the active cooling process and allowing faster charging.
  • Increases efficiency for electrified vehicle operation in cold conditions, in the order of 72 kWh/year (approx. 21.6 kgCO2e/year) per vehicle in cold northern regions.
  • Provides longer component life, in particular for the battery, due to enhanced thermal management and lower drain at cold. Potential reduction of battery material (1-2kg) and downsizing of heating devices.


  • Extends vehicle range and reduces operational cost due to better electric efficiency in colder regions, approx. 36 Eur/year per vehicle.
  • Allows to reduce vehicle cost and weight through downsizing of battery, heaters or other thermal management devices. Saving up to 70 Eur if battery is downsized.

Categories of Application

Maturity Stage

  • Medium and large scale commercialization
  • Small scale commercialization
  • Initial market commercialization
  • Prototype testing in the real world
  • Prototype testing 1:1 in the lab

Looking For

Activity Region

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