## 3 Results  
_Georreferencing of Biogas in Each Province Studied_  
The georreferenced data relating to the energy production capacity using pig manure are shown in Figure 3, where dark yellow shows the municipalities chosen, according to Table 1. Furthermore, the radius of influence considered is 25 km for each area studied, and the blue points represent the municipalities inside each radius with farms and biogas production. Through Equations (1) and (2) it is possible to determine the total manure production (\(TP_{p}\), m\({}^{3}\)/year). For the pig manure production (\(PP_{c}\), m\({}^{3}\)/year), an average value of 1.6 m\({}^{3}\) per animal was considered. The porcine census (\(C_{c}\), number of pigs) of the municipalities in the established area of influence was considered (Table 1). \[TPp=PPc\cdot Cc \tag{1}\]  
For the considered areas, 1,563,274 pig heads are established, which accounts for 36.85% of the pigs in Castile and Leon. The number of pigs considered in the study accounts for an annual manure production of 4,377,952 m\({}^{3}\). Production of biogas per animal (\(\text{PP}_{\text{biogas}}\), m\({}^{3}\)/pig) was calculated considering average values of the organic matter content (OM, kg/m\({}^{3}\)) in the liquid manure (4-5%), liquid manure daily production, and average yield of biogas (\(Y_{\text{biogas}}\), m\({}^{3}\)\({}_{\text{biogas}}\)/kg OM) reported for this kind of substrate, according to Equation (2). Mean values were obtained from [39]. \[PP_{\text{biogas}}=PPc\cdot OM\cdot Y_{\text{biogas}} \tag{2}\] \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Province** & **Area of Influence** & \begin{tabular}{c} **Porcine** \\ **Livestock (Pigs)** \\ \end{tabular} & \
\begin{tabular}{c} **Biogas** \\ **(m\({}^{3}\)/d)** \\ \end{tabular} &
\begin{tabular}{c} **Production of** \\ **Biogas (kWh/d)** \\ \end{tabular} \\ \hline Segovia & Cuellar & 447,612 & 35,808.96 & 225,596.45 \\ Segovia & Segovia & 119,493 & 9559.44 & 60,224.47 \\ \hline Soria & Almazan & 113,053 & 9044.24 & 56,978.71 \\ Soria & Soria & 195,430 & 15,634.40 & 98,496.72 \\ \hline Salamanca & Alba de Torres & 92,725 & 7418.00 & 46,733.40 \\ Ciudad Rodrigo & 20,007 & 1600.56 & 10,083.53 \\ Guijuelo & 21,599 & 1727.92 & 10,885.90 \\ Peñaranda de Bracamonte & 70,968 & 5677.44 & 35,767.87 \\ Salamanca & 47,139 & 3771.12 & 23,758.06 \\ \hline Zamora & Benavente & 127,353 & 10,188.24 & 64,185.91 \\ Toro & 35,539 & 2843.12 & 17,911.66 \\ Zamora & 122,087 & 9766.96 & 61,531.85 \\ \hline Burgos & Aranda de Duero & 100,076 & 8006.08 & 50,438.30 \\ Burgos & Burgos & 50,193 & 4015.44 & 25,297.27 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Porcine livestock census of the studied municipalities. Figure 3: Areas of influence of 25 km from the municipalities with higher energy demand. According to this calculation, biogas production averaged between 0.08 and 0.11 m\({}^{3}\) per day and animal. Considering the calorific power of the biogas (PCbiogas, kWh\(\cdot\)m\({}^{-3}\)) in the range of 6 and 6.5 kWh/m\({}^{3}\), for the calculations of the study a value of 6.3 kWh/m\({}^{3}\)[39] is considered. Through Equation (3) it is possible to determine the daily biogas production of the area of influence (Pbiogas, kWh/day). \[P_{biogas}=PP_{biogas}\cdot C_{c}\cdot PC_{biogas} \tag{3}\]  
It is calculated with Equation (2) and reflected in Table 1. Inside the areas of influence, a total biogas production of 699,243 kWh/d was obtained. To know the power and incidence of distributed biogas generation on the energy consumption in the area under study, the average electricity consumption of Spain is considered: electricity consumption in Spain per capital amounted to 1.56 MWh/inhabitant-year (2019) in the residential sector, with electricity being the first source of energy consumed in said sector, followed by natural gas with approximately half of the energy consumed in households [2]. In this case, the electricity demand in the municipalities under study ranged from 209% (Cuellar) to 1.3% (Burgos).