Selective solar absorbers: A cost effective solution for access to clean energy in rural Africa

Abstract

In this present era of global energy crisis there is a greater need to turn to renewable, cost effective and sustainable energy resources. In rural Africa, in particular, the demand for domestic energy is even higher. This is exacerbated by inadequate grid electricity infrastructure. This state of affairs has culminated in massive deforestation and desertification of some parts of Africa. One technology solution is to harness the energy from the sun through solar absorbers. This has applications in domestic heating – such as heating water (solar geysers) and cooking food. Early solar energy technologies were not readily accepted in Africa because of high initial investment cost and low efficiency, particularly so for the less affluent rural populace. Presently, there is a re–look into the solar energy technologies with emphasis on cost effectiveness and sustainability. In this paper we present new results on a novel selective solar absorber material. Laboratory tests show that it is about 30% more efficient than the best alternative on the market. Our novel selective solar absorber material comprises carbon nanoparticles embedded in a NiO matrix on an aluminium substrate. It shows enhanced solar radiation absorptance and low thermal emittance properties. The sol-gel recipe that is used to manufacture the material has additional advantages of being environmentally friendly and of having a low production cost. We report on a planned prototype development programme to take the laboratory solution into the field, and highlight the likely impact this will have on rural communities. The low cost aspect of this novel solution makes it particularly suitable for the African continent