# Biomass District Heating Systems Based on Agriculture Residues
## 4 Application of the Methodology
The required percentage of agriculture biomass in order to fully satisfy the demand only with own local resources should be 80.7% for municipalities with less than 2000 inhabitants, 88.0% for municipalities with population between 2000-5000 inhabitants and 93.7% in municipalities with a population above 5000 inhabitants. If we take into account only agricultural biomass availability for the same classification of villages the percentages are 1%, 0.6% and 0.5%. As shown in Figure 9, the amount of agricultural biomass varies between 0-855 t with an average for the municipalities of 85 t/year. Figure 8: Agriculture biomass potential per municipality. Regarding the contribution of agricultural biomass according to the power of the systems, the amount of biomass provided for powers ranging between 4.5 and 69 MW is shown in Figure 9. For the region under analysis only three systems have a potential for agriculture biomass supply above 500 t/year with power between 10 MW and 40 MW. Figure 10 shows the Internal Rate of Return (\(IRR\)) of BioDH systems only with forest biomass in the municipalities under study. The variation of the economic profitability index (\(IRR\)) for facilities with only forest biomass varies between \(-0.4\) and \(14.6\%\), with an average profitability of \(4.4\%\). In Table 7 are presented mean \(IRR\) values for municipalities classified in three groups. In those municipalities below 2000 inhabitants mean \(IRR\) value is \(4.73\), in those between 2000 and 5000 inhabitants the mean \(IRR\) value is \(4.37\) and for those above 5000 inhabitants the mean \(IRR\) is \(3.86\). Those are mean values for the classification in terms of population size. It must be highlighted that meanwhile these are mean values, there is a relevant number of municipalities with \(IRR\) values above 10%. These values are above the current economic return of money, therefore, it is considered an acceptable value for private investors, although the risks  
Figure 10: Internal Rate of Return (\(IRR\)) systems only forest biomass. Figure 9: Agricultural biomass potential per installed power. associated with investments of this type could require higher returns. In the case of Public Investors, profitability values are acceptable. In addition, governments can get involved in projects by assuming the investment or giving low interest financing, in this case private investors can get better project yields due to leverage. Figures 11 and 12 show the Internal Rate of Return (_IRR_) adding the potential use of local agriculture residues. Figure 11 shows the percentage contribution of local agriculture residues and Figure 11 shows the distribution in terms of population. Considering the use of agricultural biomass and its lower price with respect to the transport of forest biomass from other municipalities, the average profitability of BioDH with mixed fuel is improves very slightly from 4.32 to 4.36% (Figures 11 and 12). This is an expected result due to the very reduced local availability of agriculture residues in this region for the municipalities that are under the criteria for analysis of BioDH. The improvement is not very appreciable because the amount of agricultural biomass of the different municipalities it smaller than the forest and, therefore, only cover a reduced fraction of the total heat demand. In addition, although that the forest biomass has cost slightly higher, the difference is not sufficient enough to show a clear variation with the very reduced available amount. Although the increase of profitability is not high enough for the combined forest/agriculture fuel compare to the only exploitation of the forest resource in the region under study however there are points of interest associated to this combination. Among them can be highlighted that without a penalty of cost there is an increase of local biomass resource. It has an additional positive impact in the local economy with creation of new jobs and giving an additional value for the local agriculture  
Figure 11: _IRR_ per % agricultural biomass available.