Energy efficiency and carbon dioxide emissions of agricultural tractors using different powertrains
Klaus Kivekäs, Antti Lajunen
Abstract
This article presents an analysis of the power requirements of agricultural tractors in different operations and the yearly energy consumption, energy efficiency, and CO 2 emissions. The analysis included diesel, biodiesel, parallel hybrid, series hybrid, natural gas, biogas, fuel cell, hydrogen internal combustion engine (ICE), and battery electric tractors. Tractor simulations conducted using the Autonomie simulation software were used as reference data for calculating the energy consumption of different types of tractors on a typical 100 ha Finnish grain farm. The power requirements and duration of different tractor operations were defined for the farm. The analysis considered both well-to-tank (WTT) and tank-to-wheels phases. The pathways, which included WTT emission values and energy conversion factors, were defined for the production of each fuel type and energy form. For the diesel tractor, the yearly well-to-wheels (WTW) emissions were 249 kg CO 2 e/ha. The battery electric, fuel cell, hydrogen ICE, and biofuel tractors showed high potential for reducing emissions. The battery electric model reduced emissions by 96% compared to the diesel model. The lowest emissions were achieved by the biogas version, for which the biomethane was produced from wet manure. The WTW emissions of the biogas tractor were negative because of the high amount of emissions credit provided due to the prevention of anaerobic decomposition of the manure. The natural gas tractor reduced WTW emissions by 7.6% compared to the diesel version while the hybrid electric models increased emissions, with the series hybrid increasing the emissions by 10.5% compared to the diesel tractor. • Different agricultural tractor powertrains were analyzed in farming context. • Pathways were defined for the production of each fuel type and energy form. • Power requirements of agricultural tractors were analyzed in grain production. • Battery electric tractor reduced yearly emissions by 96% compared to diesel tractor. • Biomethane produced from manure was shown to be carbon negative.