By Lehlohonolo Lehana.
The City of Cape Town is nearing the production of electricity from its landfill gas project.
The project works through the combustion of landfill gas, which is primarily made up of methane.
Perforated pipes or ‘wells’ are dug into the landfill site to extract the gas. The wells are then connected to the flare compound where it is combusted or diverted to a gas engine to generate electricity. If gas is not used in the engine, it will be flared.
The project has also been designed in such a way that the city can earn ‘carbon credits’. A carbon credit is earned when an entity destroys one ton of greenhouse gas, that would otherwise be released into the atmosphere, and they can be sold as emission offsets under the carbon tax through the Carbon Offset Administration System.
Engines have been delivered to the site, and are currently in the process of being connected to the landfill gas extraction system that has been operational since March 2018. It is expected that the project will generate approximately 2MW that will be added to the city’s grid, and offset some demand from Eskom whose energy prices continue to escalate.
2MW is a small fraction of the city’s total demand which means it is unlikely to provide extra protection from load shedding or enable a reduction in tariffs. It is however an important step forward in the city’s mission to reduce reliance on the state power utility and meet emission reduction targets, the city said.
“The city is currently focused on renewable energy purchases and generation, and other energy efficiency interventions to reduce our dependence on Eskom over time,” said mayoral committee member for energy Beverley Van Reenen.
“We are prioritising energy sector reform and climate change mitigation, which remain of great importance given our country’s energy constraints and the changing energy governance landscape. The city remains committed to all new ways of thinking to ensure that our city is future-fit. Waste-to-Energy is the ultimate form of energy efficiency and we welcome this initiative,” she said.
South African National Energy Development Institute’s (Sanedi) general manager Barry Bredenkamp said the benefits of using landfill gas to produce electricity were numerous, but key was the fact that this process removed and avoided the emission of additional harmful gases that were normally released straight into the atmosphere.
“This gas is furthermore put to productive use by generating much needed electricity in the current constrained energy situation the country finds itself in,” Bredenkamp said.
Bredenkamp said waste-to-electricity projects such as this had the potential to address the issue that South Africans are suffering from unreliable electricity – although it was limited at this stage.
“In the current situation we find ourselves in in the country, every kWh (unit of energy) generated from alternate sources should be welcomed and if this technology is replicated at all sizeable landfill sites in South Africa it could make a sizeable difference, “Bredenkamp said.
He said there was a cost to installing the technology used for the process of extracting and converting the waste gas to energy and the connection to the distribution grid, but this was significantly cheaper than the current generating costs from Eskom.