Phase Change Materials

Currently, CSP power plants use sensible heat storage systems based on synthetic oil or molten salts, which need large amounts of materials and therefore large tanks making the systems very expensive. Use of phase change materials (PCMs) provides the advantage of much larger specific storage capacity reducing the cost of the material and the storage tanks.

PCMs have some drawbacks, most important of which are low thermal conductivity, and large volume changes during phase transition. Moreover, some PCMs, such as salts, are highly corrosive, especially at high temperatures. One of the promising ways to solve these problems is to encapsulate the PCM and use it in a packed bed heat exchanger. Macro-encapsulation of the PCM also helps in the separation of the PCM from other fluids where needed, increases the heat transfer rate by improving the surface area to volume ratio and provides a self-supporting structure for the PCM in molten state.

We have introduced a number of innovations resulting in macro capsules of PCMs that take care of all of these concerns. The goal is high temperature thermal storage for power plant application by developing very high temperature (300-10000 C) thermal storage in PCM contained in ceramic or metal preformed structures. These salt filled balls can turn water into steam which powers turbines producing electricity.