Editing Renewable resource (section)

===Biogas===
{{main|Biogas}}
[[Biogas]] typically refers to a mixture of [[gas]]es produced by the breakdown of [[organic matter]] in the absence of [[oxygen]]. Biogas is produced by [[anaerobic digestion]] with anaerobic bacteria or [[fermentation (biochemistry)|fermentation]] of biodegradable materials such as [[manure]], [[sewage]], [[municipal waste]], [[green waste]], [[plant material]], and crops.<ref>[[National Non-Food Crops Centre]]. [http://www.nnfcc.co.uk/publications/nnfcc-renewable-fuels-and-energy-factsheet-anaerobic-digestion "NNFCC Renewable Fuels and Energy Factsheet: Anaerobic Digestion"], Retrieved on 2011-02-16</ref> It is primarily [[methane]] ({{chem|CH|4}}) and [[carbon dioxide]] ({{ CO2}}) and may have small amounts of [[hydrogen sulphide]] ({{chem|H|2|S}}), moisture and [[siloxane]]s.