UPGRADING BIOGAS TO BIOMETHANE BY USE OF NANO-STRUCTURED CERAMIC MEMBRANES

In order to meet the demands of growing economies while considering environmental implications, the use of clean and renewable sources of energy has increasingly become of interest. Biogas utilisation is a means by which these rising needs can be met. This involves the use of waste materials; which are deposited on a daily basis by agriculture, sewage, household, to produce energy that may be used for heating, electricity, transportation and other daily needs. This paper would look into the use of nano-structured ceramic membranes for the upgrading of biogas to a high value fuel that can be used for a variety of purposes. The use of membranes offers great advantages including low running costs, high efficiency and the elimination of the need for phase change of the gas. Experiments were carried out using membranes of different pore sizes (15nm, 200nm and 6000nm) to ascertain which would be the most suitable for use in terms of permeability and yield of product gas. The 15nm membrane showed the greatest exit flow of methane compared to carbon dioxide and a mechanism approaching an ideal knudsen regime. Taking into account the effect of molecular weight and viscosity, these results show that the smallest membrane pore size of 15nm had a greater impact on the flow mechanism and thus improvement can be made by modification of the membrane to achieve a mechanism of surface diffusion of the particles.