ظرفیت استحصال بیوگاز از فضولات دامی (مطالعه موردی: شهرستان جوین، استان خراسان رضوی)

Abstract
Introduction
The current trend of energy consumption in the world has faced humanity with two major crises of environmental pollution and the increasing acceleration in the depletion of energy resources. Environmental pollution, the phenomenon of climate change and non-renewability, which are among the main challenges of using fossil energy sources, due to unsustainable development, incorrect patterns of energy consumption, population growth, etc., have continued with greater intensity in recent years. How to produce and use energy carriers in different consumer sectors is one of the effective factors in creating environmental pollution on a local, regional and international scale. The consumption of fossil energies leads to the reduction and in the end, the exhaustion of their resources and reserves. For this reason, the optimal use of energy in the process of economic development has always been considered as an important goal in sustainable development. Various researches have been conducted regarding the importance of biogas production in economic, social, cultural and environmental fields in the countries of the world and Iran. For example, the economic estimation of electricity production from biogas in pig farms in Thailand was discussed. For this purpose, two processes were considered. First, electricity generation by removing H2S from the produced biogas and the other without removing it. The reason for this is that H2S will cause corrosion of the metal parts of the generator in the process of producing electricity from biogas.
Among the most important reasons that double the necessity of doing research, the following can be mentioned:
1- The use of raw waste that contains pathogenic agents in the surrounding agricultural lands, which often belong to livestock farmers; it pollutes the soil. If animal waste is used in the biogas process, while the waste is processed and turned into fertilizer, pathogenic agents will also be completely destroyed.
2- At present, there are 14 active greenhouse units in Joveyn city, which require heating systems to heat the greenhouse environment in winter. The predominant fuel for heating systems is city gas due to its cheapness and availability. In the cold seasons of the year, due to the drop in gas pressure, in order to provide a stable supply of household gas, greenhouse units are cut off, which has caused the loss of agricultural products and financial damage to the units. Therefore, biogas can be used as a sustainable fuel in the absence of municipal gas.
In this research, the feasibility of biogas production from animal wastes of Joveyn Khorasan Razavi city will be discussed and the parameters effective in the possibility of implementing the project will be investigated.

Methodology
Jovin city is one of the western cities of Razavi Khorasan province, centered on Niqab city. The presence of large industrial factories such as Jovin electric motor factory (Jamco), Jovin sugar factory, Jovin animal feed factory and various large and small workshops make this city the industrial hub of the Western Khorasan Razavi. In addition, this city is an agricultural hub and sugar beet, wheat and especially pistachio are among its important products.
First, by referring to the Agriculture Jihad of the city, the number of farmers and the approximate number of the livestock population of the city were estimated. Joveyn city has more than 1338 farmers and an approximate number of 7729 heavy livestock. Then the livestock population was divided into six categories of purebred cows and calves, mixed cows and calves, indigenous cows and calves, buffalo, sheep and goats according to the type of livestock. In the next step, the production tonnage of livestock waste for each animal was calculated during one year. Then, by referring to the sources, the coefficients that can be collected of livestock wastes were extracted. Having the coefficients of collecting livestock wastes and the number of heads, the volume of wastes that can be collected was calculated separately according to the type of livestock. Finally, knowing the potential of biogas production from each ton the biogas production potential of fresh cow, goat, goat, sheep and lamb excrement was calculated during one year.
Biogas production potential is 281 cubic meters per ton of fresh cow excrement and 120 cubic meters per ton of fresh goat and goat excrement as well as sheep and lamb. Based on this, it is possible to calculate the potential of biogas produced from animal waste that can be collected in one year in the city as follows:
32425740=(120*120)+(120*35363)+(281*38508)+(281*60912)=production potential of biogas from animal waste in the city (cubic meters per year)
It can be seen if all the livestock wastes of the city (136,826 tons per year) are used. About 32425740 million cubic meters of biogas will be produced per year.
According to Table 2, the calorific value of biogas is 5.96 and the calorific value of natural gas is 7.52 kilowatt hours per cubic meter. Therefore, the calorific value of biogas is equal to 0.79 of the calorific value of natural gas, as mentioned, if all the animal wastes that can be collected in the city are used, biogas equivalent to 32.4 million cubic meters per year will be created. Considering its calorific value, this biogas will be equivalent to 25616346 cubic meters of natural gas.

Conclusion
Note that this technology, in addition to energy production, has other advantages. This amount of waste that can be collected, if it is left in the space in this way, the resulting methane, which is left in the space and is not consumed, in addition to causing the warming of the earth's air, also causes many environmental problems brings. Also, the use of this technology will create significant added value. Considering the high potential of the country in the production of biogas, if all the villages and industrial cattle farms of the country use this technology, the added value of the agricultural sector can be increased due to the production of enriched fertilizer and the added value of the energy sector due to the production of biogas and then electricity. It will be considered. Therefore, the use of this technology, in addition to other benefits, can also contribute to economic growth. Based on this, it is suggested that all industrial cattle farms and villages use this technology; In addition to achieving the mentioned advantages, the country's economic growth will also increase.