A model simulating an autonomous battery electric vehicle system for agricultural field use was created, assuming a 200-ha conventional cereal farm in Swedish conditions. The different subsystems ...were verified against sources in the literature, field experiments and general common practice. The model was used to compare two different charging systems (conductive charging and battery exchange) for battery electric tractors to each other. A comparative simulation was made with conventional diesel systems (fully autonomous or manned for 10 h d−1). The simulation results indicated that battery exchange was generally a faster system than conductive charging. The results also showed that both electric systems were able to achieve similar active time during spring field operations as a corresponding system of a simulated manned diesel tractor for battery sizes from 50 kWh and charge powers from 50 kW.
•A dynamic discrete-event model of a 200-ha Swedish grain farm was constructed.•Autonomous electric tractors and diesel counterparts were simulated and compared.•Weather and charging queues had high impacts on time requirements.•Electric tractors compared well with manned diesel systems in spring operations.•Battery exchange systems outperformed conductive charging in most cases studied.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Interest in the electrification of agricultural vehicles is increasing along with growing interest in autonomous vehicles. Individual technologies have been well-explored, but not their combined use ...and the effects on agricultural fieldwork. In this study, cost analysis was conducted based on a simulated vehicle system with 50 kW self-driving battery-electric drive (BED) tractors. The analysis included battery degradation due to cycling and the cost of inadequate machine capacity, as these factors are suspected to be problems for electric tractors. A dynamic discrete-event vehicle system model, a linear timeliness model and a one-dimensional battery cell ageing model were assumed. Costs obtained were compared with those of contemporary manned diesel-based systems. BED systems had equal or lower annual costs compared to conventional manned diesel-based systems; this was due to lower costs for fuel and maintenance, while providing adequate capacity and lower energy usage. Sensitivity analysis showed that operating costs were of greater significance than investment costs. The generally more expensive investment costs of BED systems were outweighed by the reduced operating costs for several different BED system systems. Battery degradation costs and timeliness were influential, but not sufficient to make the system uncompetitive. The synergistic effect of vehicular autonomy and BED outweighed several of the drawbacks of BED systems, such as frequent recharging, increased transport and reduced consecutive work time.
•Cost analysis was performed for a simulated agricultural, self-driving BEV system.•Timeliness and battery degradation costs were not detrimental to BED.•BEV systems had lower or equal annual costs compared to equivalent diesel systems.•Operating costs had a larger impact on annual costs than investment costs.•Autonomy mitigated BEV drawbacks (frequent recharging, reduced work time).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•A comparison between a conventional tractor and light electric tractors was made.•Economic and environmental impacts of vehicle weight was included in the analysis.•Soil compaction effects ...constituted 26% of the climate impact and 20% of the cost.•Lighter, electric tractors had 33% reduced cost and 72% reduced climate impact.•Lowered vehicle weight was show to be an important benefit in technology shifts.
Modern agriculture rely on heavy machinery that has increased risk of detrimental soil compaction of arable fields. This can lead to negative effects such as reduced yields, reduced field trafficability and increased fuel use. Electric, autonomous tractors makes it possible to replace one heavy machine with several lighter without increased labour costs. In this study, the economic and environmental effects of reduced soil compaction for smaller autonomous tractors were assessed and compared to a scenario with conventional tractors. A discrete event simulation of a Swedish 200 ha grain farm with clay soil was used for the calculations. The electric, autonomous system had lower soil compaction impacts as well as other benefits, and reduced cost in total from 385 to 258 € ha-1 and the climate impact from 270 to 77 kg CO2eq ha−1 compared to the conventional scenario. Soil compaction constituted 20% of the cost and 26% of the climate impact for the conventional scenario. It was concluded that soil compaction was impactful in machinery studies, especially on heavier soil like clay, and should not be omitted. Soil compaction avoidance alone was not impactful enough to warrant a change to electric, autonomous tractors but it reinforced already existing trends and further improved the cost and environmental benefits.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
There is an increased interest for battery electric vehicles in multiple sectors, including agriculture. The potential for lowered environmental impact is one of the key factors, but there exists a ...knowledge gap between the environmental impact of on-road vehicles and agricultural work machinery. In this study, a life cycle assessment was performed on two smaller, self-driving battery electric tractors, and the results were compared to those of a conventional tractor for eleven midpoint characterisation factors, three damage categories and one weighted single score. The results showed that compared to the conventional tractor, the battery electric tractor had a higher impact in all categories during the production phase, with battery production being a majority contributor. However, over the entire life cycle, it had a lower impact in the weighted single score (−72%) and all three damage categories; human health (−74%), ecosystem impact (−47%) and resource scarcity (−67%). The global warming potential over the life cycle of the battery electric tractor was 102 kg CO2eq.ha−1 y−1 compared to 293 kg CO2eq.ha−1 y−1 for the conventional system. For the global warming potential category, the use phase was the most influential and the fuel used was the single most important factor.
The agricultural sector is currently highly dependent on fossil fuels, with diesel being most prominent. There are however both historical and modern alternatives that have not been subject to enough ...evaluation to disregard them as suitable alternative. This report aims to theoretically investigate the feasibility of converting a conventional diesel driven tractor to run on electricity, delivered via a cable connected to either the main power grid or on-site electric production, such as photovoltaic. Delivering electricity to the machine via a cable is a method with historical roots in the early 20th century and in the present day mining industry. The economic and technological potential of the technique are evaluated, along with the examination of several different motor powers, voltages, losses and construction ideas. The report finds the technique to be both possible as well as long term economically and environmentally beneficial. To realise this method however, some deviations from the present methods of agricultural farming must be made, considering the more advanced driving patterns, the limited mobility and the requirement for extra driver awareness. Furthermore, this study finds further research in this field necessary, and the construction of a functional prototype highly desirable.
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