Economic viability of the use of olive tree pruning as fuel for heating systems in public institutions in South Spain

Biomass from olive tree pruning could be used as fuel for heating systems in boiler, thus helping to mitigate CO2 emissions and reducing the dependence on fossil fuels. It also helps to reap secondary benefits, such as the creation of employment in rural areas. In the present study, an economic viability analysis about the use of olive tree pruning as fuel for heating systems in public schools of Lucena (Andalusia, Spain) have been carried out. This town has been selected due to its proximity to olive tree plantations. The heat cost calculations were based on the standard VDI 2067. Eventually, a sensitivity analysis to assess the effect of prices variation over the time needed to recover the investment has been carried out. It can be concluded that, in many cases, subsidies are needed to promote modern biomass technologies, to compensate for non-internalized external costs of fossil fuel systems. In case a subsidy up to 50% of the investment is applied, payback is reduced, thus biomass boiler using olive tree chips is strongly recommended. Energy cost using olive tree chips is highly dependent on the high variability of the boilers working period. In all case studies, based on the sensitivity analysis, a maximum radius of 5 km of olive trees cuttings is enough to feed the public school boilers of the town. Also, it can be seen that the cost of energy considering either olive tree chips or olive pits is similar.