| Biogas methane is methane created from | | | | consists of feeding biomass to a large digester, in |
| biologically created organic matter. The important | | | | which methane-producing bacteria, under airless |
| thing to remember is that the term has entered | | | | conditions, convert it into the energy-rich biogas. |
| common usage through the need to distinguish | | | | The action of mixing and heating with the digester |
| biogas derived methane from fossil fuel methane. | | | | allows the bacteria to come into contact with the |
| Fossil fuel derived methane is known as 'natural | | | | feedstock material, which provides food for the |
| gas'. Natural gas comes from mineral reserves, | | | | bacteria to multiply and convert the complex |
| where it has been stored in the ground since its | | | | organic compounds into much simpler mostly |
| formation from living plants and animals hundreds | | | | soluble compounds. For example, sugars and |
| of thousands of years ago. Natural gas/methane | | | | starches, which then react in further stages giving |
| also comes sometimes from coal mines and coal | | | | off methane gas, which comprises about two |
| measures which emit it. | | | | thirds of biogas. The gas, a mixture of methane |
| So, in other words, biogas methane means | | | | and CO2, is used for direct combustion in cooking |
| 'green', 'renewable' methane, as opposed to | | | | or lighting applications, or to power combustion |
| natural gas which when burnt contributes to the | | | | engines for motive power or electricity generation. |
| greenhouse effect. | | | | Methane (CH4) biogas technology is a renewable |
| In addition to the biogas methane energy sources | | | | energy technology that uses various forms of |
| usually talked about, there are others which are | | | | biomass (animal dung, crop waste) and converts it |
| not mineral gas created and these are either | | | | into a useful energy source in the form of a gas |
| natural and un-natural in their origins, as follows:- | | | | (about 70% methane), via anaerobic microbial |
| 1. Gas being created naturally all the time in peat | | | | digestion. Methanogens are organisms that make |
| bogs and organic marine silts; | | | | methane via a unique metabolic pathway with |
| 2. Methane produced in the stomachs of animals | | | | unique enzymes. This produces a mixture of |
| by the digestion of their foods (eg ruminants); | | | | gases, primarily methane and carbon dioxide, and |
| 3. Biogas being created in farm slurry tanks etc, | | | | a nutrient-rich slurry. The CH4 rises into the gas |
| while farmers hold it waiting for dry weather | | | | holder where it is contained by a water seal. |
| when they can spread the manure/slurry on to | | | | When the mixture of methane and air (oxygen) |
| their fields; | | | | burn a blue flame is emitted, producing large |
| 4. Landfill gas which is simply biogas created in | | | | amount of heat energy. |
| landfills where the conditions are anaerobic. | | | | Methane biogas can be used for all the purposes |
| If any sources of methane are emitted and rise | | | | in which natural gas is used, and can be used as |
| from ground level into the atmosphere they are | | | | the renewable equivalent of LNG as well. |
| thought to be very potent causes of greenhouse | | | | Methane biogas has in the past been more |
| warming. In fact, methane is about 20 times | | | | expensive to produce that simply drilling for |
| more active in absorbing the sun's heat, and | | | | natural gas and pumping vast quantities of natural |
| causing global warming, than carbon dioxide. | | | | gas to our homes and industries. The biomethane |
| Anaerobic decomposition in all these cases, | | | | needs "scrubbing" before it is clean enough to use |
| produces methane biogas. At the same time it | | | | in normal natural gas burning equipment. If it is not |
| produces, carbon dioxide, some hydrogen, and | | | | scrubbed, or not scrubbed adequately it will cause |
| other gases in traces. AD also produces a little | | | | corrosion. |
| heat, and a final product with a higher nitrogen | | | | Methane biogas is about to become much more |
| content than is produced by aerobic fermentation. | | | | important as an energy source than it has been in |
| The biogas production process which is usually | | | | the past, due to the ever rising cost of natural |
| inferred when people talk about biomethane is | | | | gas. |
| Anaerobic Digestion. This is a process which | | | | |