A versatile PCM energy storage system for building applications (Versatile PCM)

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In the UK, heating and hot water for buildings make up 40% of energy use and 20% of greenhouse gas emissions. These emissions must be reduced by over 20% by 2030, with a nearly complete decarbonisation by 2050, as part of the legally binding targets set by the Parliament in the Climate Change Act. To reach these targets and reduce the energy consumption, an innovative Versatile PCM (phase change material) energy storage system is presented.The proposed Versatile PCM system can play an essential role in synchronizing end use energy demand and supply on a short to long term basis. Versatile PCM will encourage the use of energy-efficient solutions, especially being adaptable to the British weather where the solar radiation may change dramatically during a day. Versatile PCM is a promising advanced technology in addressing the "heating on demand" energy issue in building applications. Apart from a possible modest loss of sensible heat just after charging, the thermal energy will be effectively stored at room temperature or ambient temperature, without loss, until required. When heat is required, a trigger is activated to induce heat release. Versatile PCM is an innovative and alternative energy storage measure with the advantage of controllable heat release and greatly reduced heat loss. To enhance long term energy storage at ambient temperature, installation can be placed as PCM groups, each with its own trigger, enabling release of heat only as demanded for long term needs. Normally, PCM can store heat with very high energy density, however, for long-term storage, heat loss is still a challenging problem. In conventional PCM storage, the PCMs are stored at ambient, above their melting point, resulting in continuous loss of energy. A major advantage of Versatile PCM is the use of the supercooling characteristics of PCM where heat is released only when the user triggers the crystallization mechanism, allowing long term, efficient storage.Photovoltaics/thermal solar collectors will supply a hot fluid to charge the PCM cells. The heat can be supplied to cells directly by the collectors in high solar radiation days and by the heat pump in low solar radiation days where the temperature of the heat transfer fluid can be boosted by a PV-driven heat pump. The system can also be implemented in industrial applications, where waste heat can be stored in the PCM cells and used later when it is required. Different numbers and sizes of PCM cells can be activated at different times to meet the heating demand. The flexibility in amount of heat release and available time of storage makes the Versatile PCM installation unique and especially suited to regions with high variability in weather conditions such as the UK. The system can be charged during high solar radiation days and the stored heat released according to heat demand on subsequent days. The novel technology developed through this project is much more efficient than traditional heating technologies by eliminating heat loss during thermal storage and being controllable in end use energy management, and therefore can significantly reduce the carbon emissions from the heating sector in the UK, if widely installed.