Wood and Delignified Wood for Shape-Stabilized Phase-Change Materials in Application to Thermal Energy Storage

Thousands of years have seen the wood used for many fundamental purposes, as a fuel or as a material for building houses or for creating tools and furniture. Today, many researchers aim to improve the properties of this traditional material for further innovative applications. Here we will consider the enhancement of the wood thermal features by means of its impregnation with phase-change materials (PCMs). A PCM is a substance absorbing and releasing thermal energy at a phase transition. Therefore, wood and PCMs can be composed to be useful for the thermal energy storage, that is for heating and cooling applications. Here we propose a discussion of recent literature about development and application of wood-based composite PCMs. In particular, we will consider the delignified wood. With delignification, the density and chemistry of wood can be altered, obtaining a scaffold possessing an enhanced porosity suitable for an improved impregnation with PCMs. Regarding the effect of the size of pores in wood, a discussion about the depression of the melting temperatures in composite PCMs is also provided.