Start and stop systems on agricultural tractors as solution for saving fuel and emissions

Agricultural tractors may idle from 10 to 43% of their entire operating life and this inoperative time must be minimised because it is detrimental to the environment, public health, fuel economy, and engine lifespan (Perozzi et al., 2016). On passenger cars, start and stop (SS) systems have been extensively used, but they are not currently installed in any commercial tractor. Studies show that for very short idling stops SS systems might be ineffective for the additional energy required for re-starting the engine. This study aims to investigate the potential advantages of SS systems on agricultural tractors. To this aim, the energy required for engine start-up and the subsequent emissions were measured and then compared with the energy and the emissions during idling. Moreover, a predefined control strategy of the SS system was developed, and its potential fuel and emission savings were estimated using real-world data. In terms of fuel consumption and CO emission, turning off the engine is recommended for stops longer than 4 s and 134 s, respectively. From the collected real-world data, the tractor was run on idle for 21.7% of the entire operating duration. The results obtained with the SS control strategy developed in this paper applied to the US area, where there are 1.2 million tractors of the same power level of the tractor used in this study with a yearly usage up to 850 h, would permit to save 285.6 million litres of fuel, and, respectively of 16.5 and 754 tons of CO and CO2.