# Techno-Economic Assessment of an Innovative Small-Scale Solar-Biomass Hybrid Power Plant
## 3 Results and Discussion
### Annual Balances  
After simulating the daily behavior of the different analyzed plant configurations (with varying SM and BFF values), annual balances were conducted for both the gross electric energy generated and the biomass consumption by combining the typical design year (Section 2.1) and the technical characterization (Section 2.2). However, the mentioned annual energy and biomass balances not only depended on the combination of SM and BFF considered in each analyzed case but also on the existence of limits on the amount of biomass consumed. This was because it is common for current legislation to limit the maximum fraction of energy generated from biomass [43], which is cheaper than energy generated from CSP technology. For this reason, two extreme situations were identified for each considered plant. The first corresponded to the absence of limits on biomass consumption. In this case, the mixed hybrid plant could generate during periods of no solar radiation, with the only limit on biomass consumption derived from the BFF and the maximum allowable hours of annual operation. The second extreme case corresponded to a situation where biomass could only be consumed as a complement to solar resources. In other words, in the second case, biomass could not be used for nighttime operation (direct biomass combustion without solar input). In addition to the mentioned extreme cases, intermediate limitations on biomass consumption were considered. Specifically, limits from 40% to 75% were considered, with increments of 5%, although not all analyzed plant configurations could reach all these intermediate limits due to reaching one of the aforementioned extreme situations.  
Figures 9 and 10 show the annual biomass consumption (kton/year) and gross electric energy generated (GWh/year), respectively, as a function of the SM and the biomass consumption limit for the two considered BFF values. Firstly, it is worth noting that for any of the displayed graphs, the upper white area is delimited by the extreme case corresponding to the maximum allowable hours of annual operation. On the other hand, the lower white area corresponds to the limit derived from the impossibility of biomass consumption during nighttime operation. In both figures, it can be observed that within the analyzed ranges, both biomass consumption and energy generation increase with increasing SM or the limit of the maximum fraction of energy generated from biomass, regardless of the BFF value. The increase in both variables with increasing SM is not only due to the greater contribution of thermal energy from the solar field but also, given a biomass consumption limit, a higher solar production enables a greater generation of electricity from direct biomass combustion, which increases both the biomass consumption  
Figure 8: Hourly evolution of biomass consumption (kg/s) and gross electric power generated (MW) for the four representative days (SM = 1, BFF = 50%).  
and the annual electricity generated. Regarding the influence of the BFF, when it is lower, both annual biomass consumption and gross electric energy production are lower due to the increased hours of operation at partial load.