Wasting the Nation.indd - Groundwork
Wasting the Nation.indd - Groundwork
Wasting the Nation.indd - Groundwork
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Chapter 6: Down at <strong>the</strong> dumpsTraffic, dust and noise aside, Bisasar generates 7,000 cubic metres of landfill gas (LFG)per hour. Historically, much of this simply vented off <strong>the</strong> surface of <strong>the</strong> landfill whilegas wells drew some from areas of <strong>the</strong> 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 <strong>the</strong> possibility of a fur<strong>the</strong>r 2 MW depending on <strong>the</strong>actual flow of gas. Surplus gas is flared. At present, <strong>the</strong> 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 <strong>the</strong> wells will capture 80% of <strong>the</strong>gas, implying that <strong>the</strong> remaining 1,400 m 3 /hour is ei<strong>the</strong>r vented or trapped inside <strong>the</strong>dump. 80% appears optimistic however. The US EPA assumes 75% collection but inpractice, says Mike Ewall of Energy Justice Network [2008], average collection in <strong>the</strong>US is around 50% and this for only one third of a landfill’s gas producing lifetime.In <strong>the</strong> 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 <strong>the</strong> CO 2, sulphur andhalogenated components need to be removed”. This would clearly be costly. Havingfound no o<strong>the</strong>r takers for <strong>the</strong> gas, <strong>the</strong> project <strong>the</strong>refore opted to power <strong>the</strong> generatorsdriven by internal combustion engines, which are tolerant of <strong>the</strong> low quality gas, inpreference to gas turbines which are more efficient but require a cleaner gas feed.DSW claims that <strong>the</strong> engines are environmentally efficient and overall air quality willbe improved by <strong>the</strong> project. This may merely be testimony to <strong>the</strong> poor state of <strong>the</strong> airprior to <strong>the</strong> project. According to Mike Ewall, internal combustion engines are <strong>the</strong>dirtiest way of burning LFG, producing more carbon monoxide and nitrogen oxideseven than flaring. Because <strong>the</strong> un-cleaned gas is halogenated 89 , dioxins form in <strong>the</strong>generator exhausts as well as in <strong>the</strong> flare plume.Bisasar Road is slated for closure in 2016 according to <strong>the</strong> 2004 IWMP. John Parkins,of eThekwini’s Department of Solid Waste (DSW), says this has been brought forwardto 2013. This is partly because <strong>the</strong>re has been a small increase in <strong>the</strong> amount of waste89 Halogen elements include fluorine, chlorine and bromine. They are highly reactive and so form compounds,known as fluorides etc., with o<strong>the</strong>r elements. They are toxic in <strong>the</strong>mselves and, because <strong>the</strong>y are very corrosive,<strong>the</strong> presence of halogens in landfills is one of <strong>the</strong> ways in which toxics are mobilized through <strong>the</strong> waste body.- 140 - groundWork - <strong>Wasting</strong> <strong>the</strong> <strong>Nation</strong>