33 – Energy and bio-char auto production in an olive farm and mill in Southern Italy: a symbiosis example between agricultural and energy production processes

A small olive-grove farm with olive mill located in Southern Italy, within Foggia municipality, has been the focus of a study conducted by the University of Thessaloniki and the University of Foggia in order to evaluate the feasibility to install a pyrolysis reactor in the production site. This would allow the farm to auto produce energy using agricultural residues while improving the soil quality using pyrolysis waste (bio char).

The main challenge that led to the collaboration between the farm/mill and the researchers was the need to find a sustainable way to improve the farm’s productivity. In fact the plantation, as it is common in the Mediterranean area, was very old and soil amendment was needed in order to keep acceptable productivity levels.

Once identified the use of the char derived from pyrolysis as a suitable solution, the main barrier to overcome in order to implement it was the fact that the main agricultural residues produced by the farm and suitable to power the pyrolysis reactor had high moisture content, requiring a considerable amount of heat to be dried. In addition, the two main residues, pruning and pomace, are available at different times during the year, entailing discontinuous operations.

The approach used by researchers in order to overcome such barrier was to develop a new integrated system using waste heat from the drying treatment in order to pre-heat agricultural residues and make the process more efficient. In addition, they designed the pyrolysis reactor so that its operation parameters could be easily modified and the two agricultural residues could be treated separately during the year.

The discovery process was led by the research team, which designed the integrated olive oil / bio-char / bio-oil (fuel) production system. First, they conducted a study of main agricultural residue, including their availability, quality and properties. Then, they created a pyrolysis experimental apparatus in order to test the process, its results and efficiency in a small scale. The test gave good results and allowed to set optimal operation parameters, as well as to evaluate potential savings obtainable after the system’s full implementation. The possibility to sell extra energy production to the grid was also evaluated and discussed. Finally, a SWOT (Strengths, Weaknesses, Opportunities and Threats) analysis was carried on for the designed system in order to provide the company with additional information for final implementation.

The main precondition that allowed the successful implementation of the system was the fact that the farm and mill were already integrated in the same production site. This allowed to avoid transportation costs for both agricultural residues and energy. In addition, the technology used to produce bio-char and bio-oil by the means of the pyrolysis reactor was already well known and only needed to be customised considering the specific production process.

Source: Zabaniotou, A., Rovas, D., Libutti, A., Monteleone, M., 2015. “Boosting circular economy and closing the loop in agriculture: Case study of a small-scale pyrolysis-biochar based system integrated in an olive farm in symbiosis with an olive mill”. Environmental Development 14:22-36.