| Biogas is generated if organic materials are allowed to | | | | natural gas (CNG). But CNG powered transport still |
| rot in closed, airless tanks at suitable temperatures | | | | only plays a small role within even the most |
| (20-40 degrees C). The process that produces it is | | | | developed German market, (60,000 vehicles to date) |
| called "anaerobic digestion". Biogas is a mixture of | | | | although popularity is rising, particularly among local |
| methane and carbon dioxide (CO2) and is usually | | | | transport authorities. |
| when first created contaminated with quantities of | | | | Biomethane is also used in Sweden as vehicle fuel. It |
| hydrogen sulphide (H2S). | | | | has been reported that at least seven units for |
| The main sources of biogas are plentiful being | | | | upgrading and filling of biogas are in operation at |
| municipal waste (MSW) landfills that produce landfill | | | | present. It is a renewable energy source because it is |
| gas (LFG); wastewater treatment plants (sewage | | | | extracted from the natural circulation of carbon which |
| works), industrial plants, and large scale livestock | | | | has always taken place, and importantly creates no |
| farms. It can also be produced from cattle manure | | | | net increase in carbon in the atmosphere. |
| and community or even individual house toilet waste. | | | | Biogas is not utilised as vehicle fuel anywhere near as |
| In that case each household produces their own | | | | effectively as it could be, and there are almost no |
| biogas by installing a small toilet-attached AD plant, | | | | biogas upgrading plants available in AD Plants. |
| and this is popular in China, India, and many other | | | | There are also no NGV vehicles for use of |
| developing nations. | | | | compressed natural gas (CNG) or biogas available to |
| Anaerobic digestion may either be used to process | | | | the public or sold in many countries. |
| the source separated fraction of municipal waste, or | | | | While in the short-term there is potential for |
| alternatively combined with mechanical sorting | | | | biomethane as a fuel, a further significant role also |
| systems, to process residual mixed municipal waste. | | | | exists which could be played in the mid-term by |
| These facilities are called mechanical biological | | | | biomethane-to-liquid by using biomethane as the input |
| treatment (MBT) plants. | | | | for the gas-to-liquid process. This should be noted |
| Biogas, which is also called biomethane is about 20 | | | | although we will not have room to discuss it further |
| percent lighter than air. It is an odorless and colorless | | | | here. |
| gas that burns with clear blue flame similar to that of | | | | Biogas being a renewable fuel, attracts renewable |
| LPG gas. Biogas is a good fuel. | | | | energy subsidies in many parts of the world. The |
| It can be used to fuel an engine for electricity, and | | | | fact that biogas could be used much more |
| afterward the waste heat can be used in a | | | | effectively in the west can be seen from the fact |
| communal heating power plant then producing both | | | | that it already serves more than one million people in |
| power and heat. The heat given off can also be used | | | | Nepal (reported at 4% of the population). The AD |
| for heating and drying processes. | | | | sector is also a significant employer and it reportedly |
| Biomethane is a big opportunity because it is being | | | | provides about 11,000 permanent jobs in the country. |
| viewed worldwide as an untapped source of energy | | | | If anyone needed to be convinced that 'small scale |
| that, upon recovery and pretreatment, can be used | | | | can be big' then they need look no further that the |
| to supply a portion of a nation's natural gas needs. A | | | | Nepalese experience! |
| number of new projects are being sponsored by the | | | | Anaerobic digestion which produces this gas is |
| U.S. Government for this reason. | | | | basically a simple process carried out in a number of |
| It is a regenerative (renewable) fuel with the best | | | | steps that can use almost any organic material as a |
| production efficiency of all biogenic fuels. Additionally, | | | | substrate. It occurs naturally in digestive systems, |
| it need not compete with the production of human | | | | marshes, rubbish dumps, septic tanks and in the |
| food products if the source materials are all wastes. | | | | Arctic Tundra. |
| Biogas consists primarily of methane (CH4), a gas | | | | Most people in the west producing this gas tend to |
| which can be burned to produce heat and electricity. | | | | seem to make the process as complicated as |
| Treated manure can also be transformed into a | | | | possible by trying to improve on nature in complex |
| bio-fertilizer with high agronomic value. | | | | machines, but a simple approach is also possible, as |
| It is most often collected and piped to an | | | | seen in Nepal, China, South America and India. |
| engine-generator where it undergoes combustion to | | | | The other remaining products, after digestion can |
| produce electricity. However, during energy | | | | also be useful. Further research and implementation |
| generation there is a loss of efficiency during | | | | of drying digestates from biogas plants would also be |
| transmission which would not occur if the fuel was | | | | useful however it is a totally new field of application |
| used directly, where the energy is consumed. | | | | to the west. Very similar, manure drying tunnels are |
| It would be more efficient to use it say in a vehicle | | | | not in themselves a novelty, however, up to now |
| at the point at which the energy is consumed. It can | | | | they are largely only used for drying poultry manure |
| be compressed, much like natural gas , and used to | | | | prior to combustion. |
| power motor vehicles. Both natural gas and biogas | | | | So, all the various methods of producing biomethane |
| can be used in petrol vehicles relatively easily, but | | | | need further development, but this can be done quite |
| some engine adjustments are necessary. For | | | | rapidly, and then biogas has a big chance of being |
| passenger cars, there are purpose-built vehicles that | | | | able to reduce our carbon footprints. |
| can be fueled with both petrol and compressed | | | | |