## 3 Results
A 38% efficiency has been considered for the electricity generation of a motor-generator or turbine, with combined heat and power (CHP). This is the average value of this kind of installed equipment in Europe [40]; the results are shown in detail in Table 2. The thermal energy needs of the biogas production systems (digesters) are covered since the average thermal efficiency of the equipment is 50-55%. The value of the biogas distributed generation model is completed with the economic analysis, where the following benefits are obtained: (i) renewable and safe electrical energy and (ii) CO\({}_{2}\) emissions reduction in a sector regulated by Directive 2003/87/CE. To calculate the electrical energy cost, the average value of the cost of natural gas in Spain (without taxes) is considered, for the non-household consumers, and within the 10,000-100,000 GJ range of annual natural consumption, which in 2019 was 0.03 \(\upmu\)KWh, the value is slightly higher than the EU28 average (5.7% higher than the European average). Considering the energy produced by m\({}^{3}\) of biogas and defined in the previous section, it is possible to establish the energy potentially produced and its market value (Equation (4)), where Inc is defined as expected income (Inc, \(\upmu\)/year), the biogas produc \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Province**} & \multirow{2}{*}{**Area of Influence**} & **Population** & **Energy Demand** & **Covered** & **Sustainable** \\  & & **(Inhabitants)** & **(kWh/d)** & **Energy (\%)** & **Population** \\  & & & & **(Inhabitants)** \\ \hline Segovia & Cuellar & 9583 & 40,980 & 209.2\% & 20,047 \\ Segovia & Segovia & 51,674 & 220,976 & 10.4\% & 5352 \\ \hline \multirow{2}{*}{Soria} & Almazán & 5489 & 23,473 & 92.2\% & 5063 \\  & Soria & 39,398 & 168,480 & 22.2\% & 8750 \\ \hline \multirow{4}{*}{Salamanca} & Alba de Torres & 5186 & 22,177 & 80.1\% & 4153 \\  & Ciudad Rodrigo & 12,344 & 52,787 & 7.3\% & 896 \\ \cline{1-1}  & Guijlaeq & 5633 & 24,089 & 17.2\% & 967 \\ \cline{1-1}  & Penaranda de Bracamonte & 6260 & 26,770 & 50.8\% & 3178 \\ \cline{1-1}  & Salamanca & 144,228 & 616,769 & 1.5\% & 2111 \\ \hline \multirow{2}{*}{Zamora} & Benavente & 17,935 & 76,696 & 31.8\% & 5704 \\ \cline{1-1}  & Toro & 8713 & 37,260 & 18.3\% & 1592 \\ \cline{1-1}  & Zamora & 61,406 & 262,593 & 8.9\% & 5468 \\ \hline \multirow{2}{*}{Burgos} & Aranda de Duero & 32,856 & 140,504 & 13.6\% & 4482 \\ \cline{1-1}  & Burgos & 175,821 & 751,872 & 1.3\% & 2248 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Energy demand and covered energy of the selected municipalities, considering the energy demand of the residential sector. tion (P\({}_{biogas}\), kWh/d) considering the previous determined production and shown in Table 1, and 365 established days of operation. The price of natural gas of the household consumers was calculated as follows. \[Inc=\Big{(}P_{biogas}\text{365}\Big{)}\cdot PriceNG \tag{4}\]  
The energy production from biogas as primary energy can be quantified considering Equation (4); the result is a revenue of 8,627,396 \(\upepsilon\) for the studied municipalities (Figure 4). The municipality of Cuellar (Segovia) stands out; its production from the established model generates revenues of more than 2.4 \(\times\) 10\({}^{6}\)\(\upepsilon\)/year. Meanwhile, regarding the municipality where the coming biogas production facility for the mixed farming will be located (LIFE SMART AgroMobility), the expected revenue from the implantation of this energy generation model will reach the value of 1,078,540 \(\upepsilon\)/year. Considering the natural gas emission factor (EF, \(\text{tCO}_{2}\)/kWh)-fuel displaced by biogas in the current model-established at 0.182 kg CO\({}_{2}\)/kWh [41], it is possible to determine the amount of CO\({}_{2}\) in tonnes that would be avoided (CO\({}_{2\text{-avoided}}\), \(\text{tCO}_{2}\)/year) by using the distributed biogas generation model (Equation (5)), taking into account the biogas generated energy (E\({}_{Biogas}\), kWh/year).