Three rural electrification options are analysed showing the cost optimal conditions for a sustainable energy development applying renewable energy sources in Africa. A spatial electricity cost model has been designed to point out whether diesel generators, photovoltaic systems or extension of the grid are the least-cost option in off-grid areas. The resulting mapping application offers support to decide in which regions the communities could be electrified either within the grid or in an isolated mini-grid. Donor programs and National Rural Electrification Agencies (or equivalent governmental departments) could use this type of delineation for their program boundaries and then could use the local optimization tools adapted to the prevailing parameters.

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Aerogels are nanostructured highly porous solids that present properties which are very different from other materials, i.e., extremely low densities. In this letter, the mechanical properties of aerogels have been studied with a nondestructive microindentation technique. This technique enables the continuous measurement of load-displacement curves during loading and unloading cycles by using very small indentation loads (∼1 mN), small enough to prevent cracking of the aerogels. The samples studied show two different types of mechanical behaviors; the low-density aerogels are elastic, while the denser aerogels behave as elastoplastic materials. Young’s modulus, hardness, and the elastic parameter have been evaluated for these aerogel samples. Power function relationships have been found between these mechanical parameters and the aerogel densities.

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