GREEN AND CLEAN ENERGY FOR SHARPEVILLE SCHOOLS
Four Sharpeville primary schools face a greener and cleaner future with a major R1.7 million Clean Energy Programme investment, through a partnership between SANEDI and the Gauteng Department of Infrastructure Development (GDID). The schools are Emmanuel, Kgomoco, Lehlasedi and Seliba, and the green technologies implemented in each of the schools include two solar water heaters, a bio-digester that produces biogas and bio slurry from food waste and animal waste, and energy efficient LED lighting. A special Cool Surfaces paint was applied on two of on two of the roofs, which regulates the temperature of the surface on which it is applied by reflecting the heat away from such surface, leaving the underlying surface cooler. Kgomoco and Emmanuel had suitable roofs, and for two blocks at Emmanuel, paint was applied with some blocks left unpainted for reference purposes. The schools all had in common high electricity bills, dysfunctional lighting and electric geysers, high water bills, food gardens, feeding schemes and therefore food waste, proximity to animal waste, and a lack of thermal comfort in the classrooms and food gardens. The initial audit indicated that the schools rarely switched the geysers on, preferring to use LPG to boil water; lights were not all working and food waste disposal was unhygienic. The classrooms were fitted with double T8 fluorescent tube lights and the exterior lighting consisted of uneconomical high-pressure sodium lights. The schools mostly used LPG stoves, with 4-plate electric stoves for staff. The biogas digester system construction started in March 2017 just as the drought broke with very high rainfall. It was found that a variety of factors could affect the biogas rate of production, such as layout of the biogas system, feedstock, temperature, acidity of the slurry and water/solids ratios. The digester requires specific waste inputs, so part of the solution meant ensuring that food
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waste is chopped into small pieces of approximately 2 cm3 to prevent blockages and unhygienic decay. Also, the aerobic decay (in oxygen) causes the pH of the digester to drop (become acidic), thus killing the bacteria responsible the anaerobic digestion. The resultant biogas enables the schools to reduce their dependence on LPG; the digestate allows the schools to fertilize their food gardens and improve their own food production. Schools can sell the excess digestate to local community gardens to generate income. This does require staff to attend refresher courses to ensure a functional system. High energy lights were replaced with LED lighting, lowering electricity costs and enhancing safety. In future the schools may now keep brighter lights on overnight while consuming less electricity. Schools received floodlighting, using 30W LEDs, and classrooms were furnished with T8 22W LED double tubes and the exteriors received 10W bulkheads. The greening of the schools programme saved them money, since the biogas system provides for more than one hour of cooking every day. Preliminary research results indicated that electricity bills of the schools were reduced. The usage of LPG gas has also been reduced. In the case of Kgomoco Primary School, LPG usage has been reduced to zero. The ‘cool paints’ resulted in more comfortable and learning-conducive classrooms and SANEDI hopes to replicate this model in clinics, places of care, boarding schools, correctional facilities and military bases across South Africa.
WORKING FOR ENERGY
