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

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 t DM ·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.

The Influence of the Use of Windrowers in Baler Machinery on the Energy Balance during Pruned Biomass Harvesting in the Apple Orchard

“…Consequently, the total energy input flow (EIF) being a sum of DE and IDE was calculated. Next, the energy intensity (EI), expressed in energy units per physical unit of good produced, was determined [32]:…”

“…where the pruning biomass (PB) yield is expressed in tons of harvested biomass (fresh mass, FM, or dry mass, DM) per hectare (tFM·ha −1 ; tDM·ha −1 ). The energy output flow (EOF) of the biomass harvested during the baling process with and without the windrowers was estimated according to the following formula [32]:…”

“…where MC FM is the moisture content in the fresh mass of harvested biomass, and LHV is the lower heating value of the pruned dry apple tree biomass (MJ·kg −1 ). Based on the data obtained, some other indices related to energy flow, such as the energy balance (EB) [33], the energy return on investment (EROI) [32], the energy input share (EIS) [34], and the energy productivity (EP) [35], were calculated using given equations:…”

Evaluating Logistics Performances of Agricultural Prunings for Energy Production: A Logistics Audit Analysis Approach

“…Pruning and harvesting activities can be integrated with chipping or baling [13,14]. 'Chipping' is cutting pruning wood into woodchips, which can be used as solid biomass fuel.…”

“…The storage of biomass is one of the major issues in biomass logistics and handling as it is related to the seasonal variability and cost of logistics operations [13,14]. The storage of biomass should be located and designed in a way that it could improve the total system efficiency.…”