A wide variety of potential materials for thermal energy storage (TES) have been identify depending on the
implemented TES method, Sensible, latent or thermochemical. In order to improve the efficiency of TES systems more
alternatives are continuously being sought. In this regard, this paper presents the review of low cost heat storage materials
focused mainly in two objectives: on the one hand, the implementation of improved heat storage devices based on new
appropriate materials and, on the other hand, the valorisation of waste industrial materials will have strong
environmental, economic and societal benefits such as reducing the landfilled waste amounts, reducing the greenhouse
emissions and others. Different industrial and municipal waste materials and by products have been considered as
potential TES materials and have been characterized as such. Asbestos containing wastes, fly ashes, by-products from the
salt industry and from the metal industry, wastes from recycling steel process and from copper refining process and dross
from the aluminium industry, and municipal wastes (glass and nylon) have been considered. This work shows a great
revalorization of wastes and by-product opportunity as TES materials, although more studies are needed to achieve
industrial deployment of the idea.The work is partially funded by the Spanish government (ENE2011-28269-C03-02, ENE2011-22722 and ULLE10-4E-1305). The authors would like to thank the Catalan Government for the quality accreditation given to their research group GREA (2014 SGR 123) and research group DIOPMA (2014 SGR 1543). The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement n° PIRSES-GA-2013-610692 (INNOSTORAGE). Laia Miró would like to thank the Spanish Government for her research fellowship (BES-2012-051861). The work at CIC Energigune was supported by the Department of Industry, Innovation, Commerce and Tourism of the Basque Country government through the ETORTEK CIC Energigune-2013 research program. Research at Masdar Institute is supported by the Government of Abu Dhabi to help fulfill the vision of the late President Sheikh Zayed bin Sultan Al Nayhan for sustainable development and empowerment of the UAE and humankind. Researchers of PROMES address all their gratitude to the French government for the funding of their work through the ANR SESCO and SACRE projects within the ANR SEED program. They also acknowledge the support of the CNRS, the University of Perpignan Via Domitia and the EUROPLASMA/INERTAM Company. The work at the University of Antofagasta was supported by CONICYT/FONDAP Nº 15110019, and the Education Ministry of Chile Grant PMI ANT 1201. Andrea Gutierrez would like to acknowledge to the Education Ministry of Chile her doctorate scholarship ANT 1106 and CONICYT/PAI N°7813110010
