Sustainable biomass pellets using trunk wood from olive groves at the end of their life cycle

Forest biomass is the raw material most commonly used to produce quality pellets for domestic households. However, sustainable forest biomass is not available in all regions, but there are other potential raw material sources for biomass heating systems, based on pellets. There are a large number of olive trees in the Mediterranean area, but these are not used as renewable pellet fuel because the bark cannot be used as raw material to produce quality pellets. The aim of this study is to carry out a methodology to estimate the optimal sustainable bioenergy life cycle, and the amount of sustainable residue available (trunk wood) at the end of the life of the olive grove, by optimizing the benefits, through an analysis of costs and income of the whole life process. The methodology determines the potential value of the trunks of olive trees to be used as biomass, in the form of pellets in domestic contexts and in a specific geographical area. In a case study applied to Andalusia, it has been shown that the optimal renewable life-cycle is 97 years. If policies for agricultural and energy sustainability favouring this model were adopted, this region would produce 160,000 tonnes of pellets per year, and 266,500 tonnes per year, if extended to the whole of Spain. This has a potential for providing 70.17% of the current total pellet consumption. The extension of the model to other Mediterranean countries, such as Greece and Italy, would result in an additional 124,000 and 144,000 tonnes of pellets per year, respectively.