Compact and loss-free storage technique

Taking the Netherlands off natural gas

One of the Dutch goals for the energy transition is making the build environment free from natural gas. This means all energy sources based on natural gas needs to be replaced. There are only a few alternative energy sources possible to make this transition. Some examples are wind, solar-PV and solar-thermal. A lot of these energy sources give a decentralised and fluctuating energy supply, peaking in summer. Meanwhile, the demand for heat is at its peak in winter. This creates a need for compact and loss-free energy storage techniques to facilitate this shift in time (weeks to months), to match supply and demand. In project 9.3 ARES/de Beijer RTB developed the first generation affordable and loss free heat storage. This compact heat storage was thermochemical storage in a vacuum based on the hygroscopic sodium sulfide (Na₂S) salt. Sodium sulfide was chosen for its high energy density, favourable temperature range and low cost.