EU leaders agreed on October 23rd 2014 that a domestic 2030 greenhouse gas emission reduction target of at least 40% compared to 1990 will be implemented. This means mass integration of renewables into the energy supply is necessary. However, renewable sources are mostly intermittent and therefore supply and demand can no longer be matched by controlling the supply side. As such, demand side management (DSM) is necessary. In France, smart control of electrical water boilers was able to reduce winter peak electricity demand by 5 %. The potential of localized, domestic thermal energy storage (TES) for DSM is thus apparent. Water heating in buildings is however only 30 % of total heat demand. If the total heat demand could be managed, the peak load could be reduced further.
The present TES systems are based on the sensible (STES) heat of water. However, there is a tendency towards smaller temperature differences in systems, as this improves efficiency. This strongly decreases the volumetric energy density of STES water storage tanks. Phase Change Material (PCM) based systems are characterized by substantially higher energy densities and operate with minimal temperature differences. PCM’s however have low thermal conductivities. Therefore innovative heat exchanger are required to achieve power requirements. The experimental characterization of these structures remains an open and difficult topic in literature.
A novel characterization method for latent TES systems has been developed at Ghent University. The characterization depends on linking the fraction of the energy stored to the time required to reach this fraction. Furthermore, a setup to test enhancement structures has been constructed.