Anna Cox
THE City of Johannesburg will use your rubbish to show Eskom the light. In an effort to alleviate the power crisis, the city and Pikitup are rolling out a project to produce energy-using waste from landfill sites.
By 2016, it is expected that 19 megawatts of electricity will be produced from five landfill sites – enough to power 16 500 medium-sized houses.
A pilot project being executed through the city’s infrastructure and services department at the Robinson Deep landfill is showing good progress. The toxic gases are being burnt through a flare, but by next year they will be used to power generators that will feed electricity into the grid.
The gas is produced through decomposition, which happens when organic matter is broken down by bacteria in the waste and in the soil used to cover the landfill.
As organic matter decomposes, biogas is produced. If unmanaged, the gas is emitted into the atmosphere. Its methane content is 21 times more harmful to the environment than carbon dioxide.
The new system involves retrieving the methane gas and converting it into electricity. This is done by installing pipes in the landfill. The gas is then pumped into a chimney, where it is combusted into harmless emissions.
The next phase will be to install generators to channel the gas as fuel for electricity generation. The renewable electricity will be “exported” by connecting the generators to the municipal distribution grid, owned by either Eskom or City Power.
Robinson Deep is about 10 hectares, but the system will cover 26ha once it is introduced to all five landfill sites. There are many benefits for the city, says Suren Maharaj, the acting managing director of Pikitup.
The main aims of the project are to mitigate the harmful greenhouse gases emitted from the landfills and assist Eskom with its electricity shortage.
It also presents an opportunity for the the city to generate energy from methane gas and to earn carbon credits on international markets.
Dave Harris, the general manager for landfill at Pikitup, said there was enough gas to keep the project running for 15 to 20 years, but the rate of gas production was influenced by several factors, including the age and composition of the waste, and temperature and moisture content.
When completed, this will be the biggest landfill gas-to-energy project in South Africa.