Phase change materials (PCMs) having a large latent heat during solid-liquid phase transition are promising for thermal energy storage applications. However, the relatively low thermal conductivity of the majority of promising PCMs (<10 W/ (m ⋅ K)) limits the power density and overall storage efficiency.
Unlike batteries or capacitors, phase change materials don’t store energy as electricity, but heat. This is done by using the unique physical properties of phase changes – in the case of a material transitioning between solid and liquid phases, or liquid and gas. When heat energy is applied to a material, such as water, the temperature increases.
The phase change material must retain its properties over many cycles, without chemicals falling out of solution or corrosion harming the material or its enclosure over time. Much research into phase change energy storage is centered around refining solutions and using additives and other techniques to engineer around these basic challenges.
A wide variety of materials have been studied for heat storage through the phase change effect. Paraffin wax is perhaps one of the most commonly studied, thanks to its phase change occuring in a useful temperature range. However, its low thermal conductivity limits the rate at which energy can be exchanged, hampering performance.
BioPCM brand phase-change material installed in a ceiling. This is used as a lightweight way to add thermal mass to a building, helping maintain stable comfortable temperatures without the need for continuous heating and cooling. Looking to the future, it may be that phase change energy storage remains of limited use in the residential space.
Phase change materials (PCMs) are substances that allow large amounts of energy to be stored in relatively small volumes, resulting in some of the lowest storage media costs of any storage concepts. They mimic the effect of thermal mass, which also stores heat during the day and releases it during the night.