Landfill Gas Explosive For Global Warming
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Landfill Gas Explosive For Global Warming
In response to EPA's 1991 landfill rules that pushed the industry to larger facilities, landfill operator's today pile and compact trash on the ground into giant mounds in the shape of a four sided pyramid. As originally contemplated, these mounds of trash were encased in liners to keep the wastes dry so contaminants would not be mobilized to leak into groundwater, along with monitoring systems at the site perimeter in an effort to detect leaks. Little thought had been given to landfill gas. But, because the garbage was being capped and packed down in these covered landfills often hundreds of feet deep, the wastes were substantially sealed off from the air, unlike the situation in the shallow and porous, open dumps. Practically for the first time, a new environment was created deep inside the mountains of trash in which microbes that could live in an oxygen starved, or anaerobic, environment, took over. These bacteria produced large volumes of methane as the bugs broke down the discarded food, grass and paper deep in the ground away from oxygen, which meant that about half of the volume of the landfill gas created in landfills was an explosive, as well as a global warming gas. Carbon dioxide occupied most of the other half, with trace levels of odor causing and toxic compounds sufficient to cause harm. In a twin irony, the new covers not only created the very conditions that, for the first time, produced large volumes of methane, but also erected a barrier on the top face of the waste piles preventing the gas from diffusing into the atmosphere. As a result, in these days before low permeable liners, the easiest route that the newly created gas had to escape was laterally through fissures, pipes and culverts in the ground and into adjoining basements where methane concentrations built up – until a spark would cause an explosion. Thus, EPA's rules generally don't require any attempts to collect the gas for the first five years, even though a good deal of gas is generated before then. Worse, in order to boost profits, a growing number of sites ignore the requirement to keep the sites dry. These landfills accelerate decomposition while the site is still open by adding sewage sludge, recycle leachate and delaying installation of the final cover to let in more rain. The voids created by enhanced decay recovers about a quarter of the space in the landfills to be re-sold a second time, but at a since much of that souped-up gas generation is uncontrolled. Then, 30 years after the site eventually closes, which is as long as the owner is required to maintain the site, the gas collection systems will have been turned off, and, without any more care, the . As California and other state regulators concluded, that will revive a second wave of gas generation. Against all these obstacles, the landfill industry argues that, somehow, more than 95% of the gases are captured. They do this alchemy by focusing only on the best run sites during the short time when the gas systems are at their peak. Fortunately, there is an official referee for GHG accounting – the Intergovernmental Panel on Climate Change (IPCC) – which has explored the issue in depth. The Panel acknowledged the possibility that the best landfills might achieve very high capture rates when there is functioning gas collection and the site is sealed. But, of course, the best of the best has little to do with typical long-term impacts. The IPCC pointedly noted the best operated is not the same as the average landfill. More importantly, it found most of the "fugitive emissions from landfill waste [occurs] prior to and after the implementation of active gas extraction; thus estimates of ‘lifetime' recovery efficiencies may be as low as 20%." Essentially, when gas generation is high, gas capture is low. Only when there is little gas is capturing high. It's like kids' "Double Dutch" jump ropes. View source:
Curated by Deepak Shah
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