Editing Biogas (section)

== Landfill gas ==
{{Main|Landfill gas}}
[[File:Biogas in Indonesia (903).jpg|thumb|An Indonesian community installs a cylindrical plastic biogas reactor in order to turn their organic waste into energy.]]
Landfill gas is produced by wet organic waste decomposing under anaerobic conditions in a similar way to biogas.<ref>{{cite web |url=http://www.bioenergy.org.nz/biogas.asp |title=Biogas – Bioenergy Association of New Zealand (BANZ) |publisher=Bioenergy.org.nz|access-date=21 February 2010 |url-status=dead |archive-url=https://web.archive.org/web/20100125053346/http://www.bioenergy.org.nz/biogas.asp |archive-date=25 January 2010}}</ref><ref>[http://www.epa.gov/lmop/proj/ LFG energy projects] {{webarchive|url=https://web.archive.org/web/20090103070211/http://www.epa.gov/lmop/proj/ |date=3 January 2009}}</ref>

The waste is covered and mechanically compressed by the weight of the material that is deposited above. This material prevents oxygen exposure thus allowing anaerobic microbes to thrive. Biogas builds up and is slowly released into the atmosphere if the site has not been engineered to capture the gas. Landfill gas released in an uncontrolled way can be hazardous since it can become explosive when it escapes from the landfill and mixes with oxygen. The lower [[explosive limit]] is 5% methane and the upper is 15% methane.<ref>[http://www.adelaide.edu.au/biogas/safety/ Safety Page, Beginners Guide to Biogas] {{webarchive|url=https://web.archive.org/web/20150217044037/http://www.adelaide.edu.au/biogas/safety/ |date=17 February 2015}}, www.adelaide.edu.au/biogas. Retrieved 22.10.07.</ref>

The methane in biogas is 28<ref>{{cite web |url=https://www.ipcc.ch/pdf/assessment-report/ar5/syr/SYR_AR5_FINAL_full.pdf |title=Archived copy |access-date=22 December 2018 |archive-url=https://web.archive.org/web/20181112060025/https://www.ipcc.ch/pdf/assessment-report/ar5/syr/SYR_AR5_FINAL_full.pdf |archive-date=12 November 2018 |url-status=dead}}</ref> times more potent a greenhouse gas than carbon dioxide. Therefore, uncontained landfill gas, which escapes into the atmosphere may significantly contribute to the [[effects of global warming]]. In addition, [[volatile organic compound]]s (VOCs) in landfill gas contribute to the formation of [[Smog#Photochemical smog|photochemical smog]].

===Technical===
[[Biochemical oxygen demand]] (BOD) is a measure of the amount of oxygen required by aerobic micro-organisms to decompose the organic matter in a sample of material being used in the biodigester as well as the BOD for the liquid discharge allows for the calculation of the daily energy output from a biodigester.

Another term related to biodigesters is effluent dirtiness, which tells how much organic material there is per unit of biogas source. Typical units for this measure are in mg BOD/litre. As an example, effluent dirtiness can range between 800 and 1200&nbsp;mg BOD/litre in Panama.{{citation needed|date=February 2014}}

From 1&nbsp;kg of decommissioned kitchen bio-waste, 0.45&nbsp;m<sup>3</sup> of biogas can be obtained. The price for collecting biological waste from households is approximately €70 per ton.<ref>{{cite journal|last1=Obrecht|first1=Matevz|last2=Denac|first2=Matjaz|title=Biogas – a sustainable energy source: new measures and possibilities for SLovenia|journal=Journal of Energy Technology|date=2011|issue=5|pages=11–24|url=http://www.fe.um.si/images/jet/jet4-5-internet.pdf}}</ref>