Abstract
M.Phil. (Mechanical Engineering)
Biomass is a renewable energy source that contributes approximately 12% towards world primary energy needs. However, available natural by-products from agricultural and forestry activities mostly end up in landfills. This could be harnessed for sustainable energy supply with minimal impact on global warming and climate change. Reliance on fossil fuels as a source of energy has negatively impacted the ozone layer leading to increased global warming and climate change. The high level of agricultural and forestry activities in South Africa affords an opportunity to develop a biomass based energy stream. In South Africa, rural communities which live off the electricity grid depend mainly on round wood and animal waste for heating and cooking.
To reduce demand on round wood, other sources of biomass that are available from agriculture and forestry activities can be harnessed. These agricultural and forestry wastes include elephant grass, Mopani leaves, saw dust, peanut stalks and shells, maize stalks and leaves and coffee husks. The challenge in using these loose biomass sources is their low energy and physical density. This is usually overcome by using densification technologies.
The main aim of this work was to investigate the potential to harness renewable energy from loose biomass residues for a specific village (Maphophe) in the Limpopo Province of South Africa. The loose biomass waste available at this location was identified, samples were collected and characterised in terms of density, moisture content, energy content, compatibility, combustion behaviour and emissions. Based on these parameters, a selection metric was developed to select the best candidates for biomass briquetting. The selected candidate materials were then used to produce briquettes. Optimum pressure and binders for the production of the briquettes was determined.
The produced briquettes were also characterised for energy content, combustion behaviour and emissions. The results of this investigation showed that it is possible for off grid communities to harness energy for domestic use from the agricultural and forestry residues that are produced perennially in the localities...