Harvesting and Baling of Pruned Biomass in Apple Orchards for Energy Production

Arkadiusz Dyjakon

doi:10.3390/en11071680

Abstract

Pruning residues belong to the agricultural wastes generated in the agro-food processing sector, whose energetic potential can have a significant influence on the local energy market. This study is focused on the assessment of the feasibility of using apple tree pruning residues in the form of bales for energetic purposes. The research was performed in a commercial apple orchard located in the central-western part of Poland, an area characterized by the largest concentration of apple orchard in Europe. The biomass yield, pruned bales quality, energy input and output flow, as well as the economic sustainability of the pruning-to-energy strategy were evaluated. The results indicated the available collected biomass potential in an amount of 0.69 tDM∙ha−1 per year. Pruned biomass analysis showed a moisture content of 45.1% in the fresh material, the ash content was 0.8% dry mass, and the lower heating value was 18.05 MJ∙kg−1 dry mass. Total production cost, including all steps and avoided cost of mulching, was 74.7 €∙t−1 dry mass. Moreover, the net energy balance of this value chain was very positive, giving a value of ca. 12,000 MJ∙ha−1 per year. As a result, the yearly harvested pruned biomass may be considered a good energy source for local heating systems.

Highlights

The main objectives for the European Union in terms of energy production and environmental aspects until 2020 is to cut down greenhouse emissions by 20%, to increase the use of renewable energies by 20%, to improve energy efficiency by 20%, and to achieve a 10%share of renewables in the transport sector [1]
The calorimetric analysis and further calculations resulted in an higher heating value (HHV) of 19.31 ± 0.11 MJ·kgDM −1 and an lower heating value (LHV) of 18.05 MJ·kgDM −1 (9.52 MJ·kgFM −1 ), respectively
The energy balance for harvesting was more than two times higher than that obtained for harvesting and chipping of the apple tree and baling was more than−1two times higher than that obtained for harvesting and chipping of the pruning (EB = 5.24 GJ∙ha )

Summary

Introduction

The main objectives for the European Union in terms of energy production and environmental aspects until 2020 is to cut down greenhouse emissions by 20% (concerning 1990 levels), to increase the use of renewable energies by 20%, to improve energy efficiency by 20%, and to achieve a 10%share of renewables in the transport sector [1]. Commission proposed limiting the use of food-based biofuels from 10 to 5% in this sector [2] This change raises the interest of non-feedstock substrates coming from agricultural and industrial processes that do not directly interfere with food production. The use of biomass residues for energetic purposes contributes to the reduction of fossil carbon dioxide (CO2 ) emissions that is mostly responsible for global warming and climate change [8]. This is very important taking into account that greenhouse gas emissions from the energy sector represent roughly 65% of all anthropogenic emissions [9]. The limitation of fossil fuel combustion for heat and electricity production

Methods

Results

Discussion

Conclusion