SaltX Technology and Vattenfall have signed a letter of intent to conduct a pilot project based on SaltX large-scale energy storage technology – EnerStore – at Vattenfall´s combined heat and power plant in Berlin.

The idea of the pilot project is to look at the ways in which surplus electricity can be stored as heat in dried salt.

As per Vattenfall, there is a need to develop a technology which can safely store surplus energy for weeks or months at a time.

There is an uncertainty in depending on wind and solar power due to their inconsistency.

If there is more energy being produced than the electric grid needs, the energy produced is wasted. Instead, by using salt for storage, it is possible to take the full advantage of renewable energy with an inexpensive system.

Vattenfall’s project sponsor for SaltX project Markus Witt said: “The energy stored in salt can be kept for weeks or months until it is needed.”

“By adding water to the dry salt, calcium oxide, the salt turns into calcium hydroxide. The water starts a chemical process which generates heat and the temperature will rise to approximately 120 degrees Celsius. If you add hot steam instead of water to the salt, the steam temperature will rise up to 500 degrees Celsius.

“The hot steam can either be added to the Berlin district heating network or be led through a turbine to generate electric power.”

Until now SaltX has been conducting experiments which have been successful in laboratories. The next step is to build a large reactor, which can help in studying the technique in a realistic environment. The pilot project is expected to provide heat to the district heating network.

The prototype reactor is being planned and will be built and tested next year. This reactor will only contain between 1 and 3 litres of salt. But how a full scale reactor could look like is to be seen on the basis of the testing.

As per Vattenfall, there are several unanswered questions before starting a full scale project. The idea is to make it possible to dry a large quantity of salt, placed in a large container and to do it in an efficient way. There are other areas to be looked at including the speed of the reaction as well as the control over the process.

The pilot project will be conducted with Vattenfall, Energiforsk, Sweco and the Stockholm University. This project is expected to have an initial phase of about 18 months.

Image: SaltX, Vattenfall to work on salt for energy storage. Photo: Courtesy of Vattenfall.