Potential for biogas energy
COST-SAVING: 2 ARMY BASES USE IT
Development of micro-digester tech offers alternative in energy mix.
Astudy commissioned by the SA National Energy Development Institute (Sanedi) and conducted by the University of Johannesburg’s Process, Energy, Environmental and Technology Station (UJ Peets) has found that the biogas sector has the potential to reduce rural energy poverty, reduce urban organic waste on landfill sites, and boost employment and business opportunities through the use of micro-digester technology.
Sanedi renewable energy manager Dr Karen Surridge says micro-digesters operate like rubbish disposal systems where biogas, including methane gas, is produced through the decomposition of organic waste.
The methane gas can be used to drive turbines to generate electricity, to power vehicles, or utilised in households, commerce, and industry. “We’re hoping to reduce the costs for primary energy,” said Surridge.
The research conducted by UJ Peets concluded that micro-digesters provide alternative energy sources for cooking, enabling households to move away from firewood and the expense of paraffin.
Potential as alternative energy source
The report by UJ Peets says the development of micro-digester technology can provide government with an alternative in its energy mix while achieving the objective of skills development, economic transformation and job creation.
“Biogas reportedly has the potential to generate 2.5MW of electricity in South Africa with a market potential of R10 billion,” it said.
Sanedi says the potential size of the sector is estimated to be 21 000 units, with the potential to increase to 54 000 units.
Based on this, the entity says the sector has potential to create at least 17 000 jobs and up to 150MW of daily capacity diverted from “less clean” and green energy sources, including firewood and charcoal.
SANDF’s biogas plants
In August last year, the South African National Defence Force (SANDF) and Sanedi announced their partnership in installing biogas plants at two military bases. Sanedi installed the plants and trained personnel to maintain them at the air force base and the 523 Electronic Warfare Squadron base in Makhado, northern Limpopo.
The power provided by the plants has been used in the preparation of meals three times a day for up to 200 people at the air force base, and 20 people at the electronic warfare squadron base, since February and the end of March.
Surridge says the biogas digesters have provided an alternative to much of the electricity previously used in the kitchens, and will save the base an estimated R250 000 in electricity costs over the 20year lifetime period of the plant. “The choice of a base with a small kitchen and one with a large kitchen was partly made to demonstrate that biogas plants can be tailored to specific needs and provide a wide range of solutions,” said Surridge.
The large digesters were installed underground to make them unobtrusive. This, according to Sanedi, shields the environment from any unpleasant odours that might escape. The drawback of the technology is that it is labour-intensive, requires constant attention and is difficult to get off the ground once installed.
“Daily maintenance is absolutely essential, so the process is quite labour-intensive,” said Surridge. “Once installed, a biogas system can take as long as six months to start producing gas optimally. The initial process is like feeding a baby. Waste material must be added regularly throughout the system’s lifetime and the gas must be used soon after it is produced, otherwise it dissipates. It can’t be stored or bottled.”
Sanedi says it hopes to introduce micro-digesters into the public sector, starting with correctional services.