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Global environmental benefits

Anaerobic digestion of animal waste leads to decrease of greenhouse gas emissions that influence the climate. Using biogas reduces emissions of carbon dioxide due to decrease n consumption of fossil fuels, such as benzene, coal, firewood. At the same time due to collection and utilization of biogas due to fermentation of manure a decrease in emissions of the most important greenhouse gas- methane is reached.

Greenhouse effect
The greenhouse effect is caused by gases in the atmosphere (mainly carbon dioxide CO2) which allow the sun’s short wave radiation to reach the earth surface while they absorb, to a large degree, the long wave heat radiation from the earth’s surface and from the atmosphere. Due to the “natural greenhouse effect” of the earth’s atmosphere the average temperature on earth is 15°C and not minus 18°C.
The increase of the so called greenhouse gases which also include methane, ozone, nitrous oxide, etc. cause a rise of the earth’s temperature. The World Bank Group expects a rise in sea levels until the year 2050 of up to 50 cm. Flooding, erosion of the coasts, salinization of ground water and loss of land are but a few of the consequences mentioned [13].

Reduction of carbon dioxide
Biogas plants reduce the consumption of firewood and decrease deforestation, soil degradation and resulting natural catastrophes such as under flooding or desertification. Using 1 m3 of biogas instead of 1,3 kg of firewood decreases carbon dioxide emissions by 2,6 kg, and decrease in carbon dioxide emission from substituting benzene constitutes 1,6 kg per m3.

Biogas and global carbon cycle
The natural generation of biogas is an important part of the biogeochemical carbon cycle. Each year some 590-880 million tons of methane are released worldwide into the atmosphere through microbial activity. About 90% of the emitted methane derives from biogenic sources, i.e. from the decomposition of biomass and the remainder is of fossil origin.

Reduction in methane emissions
Until now, instruments to reduce the greenhouse effect considered primarily the reduction of CO2-emissions, due to their high proportion in the atmosphere. Though other greenhouse gases appear to a smaller extend in the atmosphere, they cause much more harm to the climate.
For example, methane is not only the second most important greenhouse gas (it contributes with 20% to the effect while carbon dioxide causes 62%), it has also a 23 times higher global warming potential compared with carbon dioxide. Therefore the reduction of methane emissions can be more efficient for preventing climate change [28]. Decrease in methane emission from digestion of 1 ton of manure constitutes around 90 kg of carbon dioxide equivalent [13].

Sources of methane emissions in the agricultural field [8]
The amount of worldwide methane emissions from agricultural production comprises about 33 % of the global anthropogenic methane release.
Animal husbandry alone comprises 16 %, followed by rice fields with 12 % and animal manure with 5 % . While methane released through digestion of ruminants can rarely be reduced, methane emissions from animal waste can be captured and energetically used through anaerobic treatment.
The amount of methane emission mainly depends on fodder, animal type and animal waste systems. For example: the methane emission potential from dairy cattle in industrialized countries is about 0,32 m3 of methane per kg of volatile solids, in developing countries it is only about 0,25 m3 per kg of volatile solids.

Methane reduction potential through the application of biogas technology
Through anaerobic treatment of animal waste, respectively through controlled capture of methane and its energetic use, about 13,24 million ton of methane per year can be eliminated worldwide. In total about 4 % of the global anthropogenic methane emissions could be reduced by biogas technology.
Reduction potential of nitrous oxide emissions from agriculture
The relative climatic change potential of nitrous oxide is up to 320 times higher as that of Carbon dioxide. Nitrous oxide generation is a natural microbial process. It is produced during nitrification and de-nitrification processes in soils, stables and animal waste management systems. Fertilizing as well as special conditions during storage can immensely increase the emissions. Research shows that nitrous oxide reduction potential through anaerobic treatment of about 10 % can be assumed. This means that 15,7 million ton of carbon dioxide equivalents could be reduced on average [8].

Reduction potential of greenhouse gases emissions in the Kyrgyz Republic
Digestion of 6 058 703 tons of manure per year will prevent emission of 934.86 thousand tons of carbon dioxide equivalent into the atmosphere and decrease in fossil fuel consumption by substituting them with biogas will lead to decrease in carbon dioxide emissions.
Wide dissemination of biogas technologies in Kyrgyzstan in industrial and agricultural economy sectors and production of heat and energy for household appliances will lead to effective and sustainable decrease of ecological burden of animal wastes on the environment.