Due to advances in its effectiveness and efficiency, solar thermal energy is becoming increasingly attractive as a renewal energy source. Efficient energy storage, however, is a key limiting factor on its further development and adoption. Storage is essential to smooth out energy fluctuations throughout the day and has a major influence on the cost-effectiveness of solar energy systems. This review paper will present the most recent advances in these storage systems. The manuscript aims to review and discuss the various types of storage that have been developed, specifically thermochemical storage (TCS), latent heat storage (LHS), and sensible heat storage (SHS). Among these storage types, SHS is the most developed and commercialized, whereas TCS is still in development stages. The merits and demerits of each storage types are discussed in this review. Some of the important organic and inorganic phase change materials focused in recent years have been summarized. The key contributions of this review article include summarizing the inherent benefits and weaknesses, properties, and design criteria of materials used for storing solar thermal energy, as well as discussion of recent investigations into the dynamic performance of solar energy storage systems.

The study investigated the suitability of waste rubber powder (WRP) use as filler in adhesive formulation for plywood application. Melamine Urea Formaldehyde (MUF) was employed as resin for formulating the wood adhesive. To improve chemical properties and bonding quality of adhesive, WRP was treated by different chemicals like 20% nitric acid, 30% hydrogen peroxide and acetone solution. The treated WRP were analysed by XRD and it showed that inorganic compounds were removed and carbon was remained as major component under the treatment of 20% HNO₃. The treatment improved the mechanical properties like shear strength and formaldehyde emission of plywood (high shear strength and low formaldehyde emission). The physico-chemical interaction between the wood, resin and filler was investigated using fourier transform infrared spectroscopic (FTIR) technique and the interactions among N-H of MUF and C=O of wood and WRP were identified. The morphology of wood-adhesive interface was studied by field emission scanning electron microscope (FESEM) and light microscope (LM). It showed that the penetration of adhesives and fillers through the wood pores was responsible for mechanical interlocking. Therefore, chemically treated WRP proved its potential use as filler in MUF based adhesive for making plywood.