In the case of biomass derived fuel

In the case of biomass derived fuels, the biomethane scenario performs better in ecosystems than straw and wood, however it has more impacts on human health (mainly due to the sulphur dioxide and hydrogen sulphide emitted during the upgrading process). The wood scenario’s higher impact on ecosystems is due to a greater electricity consumption in pellets manufacturing. Main impacts in the straw scenario are derived from the wheat cultivation (25% contribution of this process to the single score indicator).

3.7. Energy indicators
The cumulative energy demand associated with the manufacturing, construction and dismantling phases (CEDc) and the Cumulative Energy Demand associated with the operation and maintenance phase (CEDo) were calculated for each scenario and compared to the solar-only operation. Raw energy from renewable resources (solar, wind, hydro energy) is not included in the calculations.

Results are described in Table 2. CEDc in hybridisation scenarios is slightly higher (1.3%) than in solar-only mode, due to the inclusion of extra boilers for the fuel’s combustion. CEDo results vary significantly in each scenario, since it accounts for the fuel’s embodied energy. The energy indicators suggest higher energy intensity for the renewable fuels, except for wheat straw, whose CEDo is the lowest (3.873 ⋅ 108 MJ/yr) followed closely by natural gas (3.876 ⋅ 108 MJ/yr).