In: Bentonite ISBN: 978-1-63482-142-1 Editor: Ajay Kumar Mishra © 2015 Nova Science Publishers, Inc. Chapter 1 CLAY AND CLAY -SUPPORTED MATERIALS FOR CLEAN ENERGY STORAGE APPLICATIONS Nicholas M. Musyoka * and Henrietta W. Langmi HySA Infrastructure Centre of Competence, Materials Science and Manufacturing, Council for Scientific and Industrial Research (CSIR), South Africa Abstract The dwindling fossil energy reserves together with the need to find cleaner energy sources have intensified investigations for alternative energy sources. Solar energy, batteries and hydrogen have featured prominently amongst the most promising sources of cleaner energy. Among other challenges, the high cost of production together with limited reliable energy storage materials have contributed to the main obstacles for delayed the widespread switch toward cleaner energy sources. Clay materials being abundant, environmentally benign, as well as having unique structural and physical properties have over the recent years been considered as potentially low cost candidates for clean energy storage either in their pristine form and/or as support materials. This chapter presents a review of recent research work highlighting the use of clay and clay-supported materials for energy storage applications. 1. Introduction Natural clays are formed by weathering of volcanic ash via a complicated process and are amongst the most abundant natural materials in the world [1]. They are also chemically inert and resistant to deterioration. The crystal structure of most clay minerals is mainly composed of sheets that are arranged in structural layers and hence reference to the terms ‘sheet silicates’ or ‘phyllosilicates’ [2-3]. These sheets are reported to be formed either by Si0 4 14- tetrahedrons or by [AlO,(OH),] 6- octahedrons containing metal cations at the interiors of the tetrahedrons and octahedrons. Crystalline clay minerals are mostly classified into seven * Corresponding author: E-mail: nmusyoka@csir.co.za.