Wasting the Nation.indd - Groundwork

Chapter 6: Down at the dumpsTraffic, dust and noise aside, Bisasar generates 7,000 cubic metres of landfill gas (LFG)per hour. Historically, much of this simply vented off the surface of the landfill whilegas wells drew some from areas of the dump that had been permanently closed. Thisgas was flared off. A more comprehensive system of wells has now been developed toprovide a fuel feed for electric generators with a capacity of 4 MegaWatts – with 2 MWmore to be installed next year and the possibility of a further 2 MW depending on theactual flow of gas. Surplus gas is flared. At present, the landfill is producing more gasthan originally estimated, according to DSW managers. In contrast, Mariannhill hasproved a relatively ‘dry’ landfill with less gas than expected.eThekwini’s gas-to-energy project document says the wells will capture 80% of thegas, implying that the remaining 1,400 m 3 /hour is either vented or trapped inside thedump. 80% appears optimistic however. The US EPA assumes 75% collection but inpractice, says Mike Ewall of Energy Justice Network [2008], average collection in theUS is around 50% and this for only one third of a landfill’s gas producing lifetime.In the words of eThekwini’s project document, this is “dirty, low calorific value gas”being composed of about 45% methane as compared with natural gas at 80-99%methane. To upgrade it, “landfill gas needs to be dried, and the CO 2, sulphur andhalogenated components need to be removed”. This would clearly be costly. Havingfound no other takers for the gas, the project therefore opted to power the generatorsdriven by internal combustion engines, which are tolerant of the low quality gas, inpreference to gas turbines which are more efficient but require a cleaner gas feed.DSW claims that the engines are environmentally efficient and overall air quality willbe improved by the project. This may merely be testimony to the poor state of the airprior to the project. According to Mike Ewall, internal combustion engines are thedirtiest way of burning LFG, producing more carbon monoxide and nitrogen oxideseven than flaring. Because the un-cleaned gas is halogenated 89 , dioxins form in thegenerator exhausts as well as in the flare plume.Bisasar Road is slated for closure in 2016 according to the 2004 IWMP. John Parkins,of eThekwini’s Department of Solid Waste (DSW), says this has been brought forwardto 2013. This is partly because there has been a small increase in the amount of waste89 Halogen elements include fluorine, chlorine and bromine. They are highly reactive and so form compounds,known as fluorides etc., with other elements. They are toxic in themselves and, because they are very corrosive,the presence of halogens in landfills is one of the ways in which toxics are mobilized through the waste body.- 140 - groundWork - Wasting the Nation