Potential Energy Production from Biogas Economically and Environmental Profitable . Case Study : Establishing a Batch Digester in “ Fogi ” Farm

DOI: http://dx.doi.org/10.24018/ejers.2021.6.5.2503 Vol 6 | Issue 5 | July 2021 70 Abstract — Recently the use of biomass for biogas production is very limited in Albania. According to data acquistion from the study, the highest share in the entire structure of urban solid waste is that of organic waste 41-61.2%. A large part of these waste are bio digestible and can used for production or utilized as potential substrate in anaerobic digestion to produce biogas, a renewable source of energy and environment friendly too. Live stocks waste and especially cow manure farms are concerned in this study because there are a high number 11813 of them are spread all over Albania. In addition, the amount of cow manure exceeds 37,693.92 ton/year. In this case study is presented a cow farm located near Tirana, capital city of Albania with 200 cow heads which in the future will become 700 cow heads. The total amount of cow manure produced in this farm is 1825 ton/year, a considerable quantity of manure available for biogas production. This paper presents the type of digester, calculation of the biogas production yield, the optained energy, the pay back period of the initial investment and the net present value of this farm batcher digestor.


I. INTRODUCTION
After 1990s in Albania, the data indicate a significant increase in urban waste generation. In the total percentage of solid urban waste, organic waste component represents the highest percentage (41-66%) at the waste composition. Many livestock farms were developed. Recently the number of them is increase up to 23654 and approximately 50 % of them are cow farms, as shown in the Table I. In 2020 the waste forms the livestock sector is estimated 383,234.4 ton. [1].
As is shown in the Table I the quantity of cow manure in 2020 in Albania is approximately 37,693.92 ton/year. The reasons that is chosen cow manure farm are: the substrate quality for biogas production, the high quantity of available manure, the methane production yield up to 63%. [2], [10], [9].
The results on biogas production in laboratory scale from cow manure (25 Nm 3 /ton) are very optimistic to implement in the concrete cow farm with 200 cow's heads. Submitted

II. MATERIALS AND METHODS
As mentioned above, the study aimed to establish a biogas production plant with cow manure nearby the "Fogi" Farm, located in Kashar village, approximately 15 km far away from Tirana, with a maximal capacity of 700 cow heads.
-Total surface area of the farm is 12,500 m 2 .
-Building surface + stalls is 5500 m 2 (Close system). Cow manure is collected within an open area in a natural dump. -Actually, this farm has 200 cow heads.
-One head produces approximately 20 -30 kg manure/day -Average monthly consumption of electric energy is 3381 kWh/year. -The price of electricity is 14 ALL/kWh without VAT. (0.14 $) -Heating-cooling system for the building is assumed from heat pumps. Taking in consideration that one head produces 20-30 kg manure per day, 200 head of cows produce 5 tons of waste per day so 150 tons of waste in 30 days.
Cow litter density is 500 kg/m 3 : -The plant will be a batch digester type similar like is shown in the Fig. 2.

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The digester volume -300 m 3 . The samples of cow manure are analyzed in the biogas lab. The method applied for the cow manure samples is the same that mentioned [3]- [5] for biogas production in laboratory scale.

III. RESULTS AND DISCUSSION
The biogas produced in the laboratory scale from cow manure is approximately 25 Nm 3 /ton.

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The monthly energy produced is 36262.5 kWh, which can be used to generate heat and electricity.

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Annually energy produced is 161 MWhel.  Establishing a batch digester in "Fogi" Farm is profitable for the company because the handling and the storage of the feedstock is already available within the farm territory; have low operation costs and low costs of the mechanical technologies; this process is also a contribution to the reduction of farm waste. [6], [7]. Total installed costs for an AD biogas plant can depend on the feedstock. Those based on manure and sewage are typically cheaper. This is because the handling and storage of the feedstock is already available [8], [9].
According to the literature review the total installed capital costs for an anaerobic digestion system vary from USD 7 310 to USD 5 050/Nm3/hour. This is for systems with hourly output capacities of 100 Nm 3 and 500 Nm 3 , respectively [8].
Taking into consideration the biogas produced from experiments in the lab, the quantity of biogas produced is 25 Nm 3 /ton in a day. From 200 head cows, the quantity of biogas produced in a day is 125 Nm 3 /ton.
The biogas produced in an hour is 5.2 Nm 3 /hour. Referring to the literature [8] and to the quantity of biogas produced in an hour we calculated the initial cost of the investment that is 38 072.91 $. Interest rate is 5%.

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The cost per kWh electricity produced by biogas is 3.28 ALL (0.0328 $)/kWh without VAT, a low price comparing with electricity price by national grid (14ALL, 0.14$). The payback period of the initial investment is 1 year and 6 months (see Fig. 3). The cash flow graphic of the investment is shown in the Fig. 4.   The Net Present Value after 15 years is 14 527 088 ALL or 145 027.8 USD.
The batch digester to be implemented in "Fogi" Farm is been studied as per real conditions.

IV. CONCLUSION
• Different biomass samples of "Fogy farm" cow manure analyzed in the biogas lab are easily biodegradable and as result was produced a considerable quantity of biogas.
• From the casestudy, the payback period is assumed 1 year and 6 months.
• The cost per kWh electricity produced by biogas is 0.0328 $/kWh, a low price comparing with electricity price by national grid (14 ALL, 0.14$) without VAT.
• The initial investment is economically profitable.