Effects of Crude Tall Oil Based Renewable Diesel on the Performance and Emissions of a Non-Road Diesel Engine

Environmental concerns and government policies aiming to increase biofuel shares have led to the search for alternative fuels from a variety of renewable raw materials. The development of hydrotreated vegetable oil (HVO) type fuels has been strong in the Nordic countries, partly due to the early use of tall oil from the forest industry as feedstock. An innovative production process to convert crude tall oil (CTO) - a residue of pulp production - into high-quality renewable diesel fuel was developed by a Finnish forestry company UPM. Paraffinic, high cetane and low aromatic CTO renewable diesel allows efficient and clean combustion, resulting in reductions of local air pollution in addition to not releasing any new CO₂ into the atmosphere during their combustion. This research investigated the influence of CTO renewable diesel on the performance and exhaust emissions of a non-road diesel engine. The examined fuels were neat CTO renewable diesel (BVN) and a blend of BVN and fossil diesel fuel oil (DFO) (50/50% v/v). Neat DFO served as the reference fuel. During a thorough test bench campaign, the engine was driven with the loads of the ISO 8178-4 C1 test cycle. The test engine had no exhaust after-treatment system, and no engine modifications or parameter optimizations were made during the tests. CTO renewable diesel proved to be beneficial in terms of CO, HC and particle number (PN) emissions. With neat BVN, a reduction of 9 % for CO, 10 % for HC, and 10% for PN compared with DFO were observed. The beneficial trends were most evident at low loads. Renewable fuel also slightly reduced brake specific NO_x emissions. CTO renewable diesel proved to be a high-quality, sustainable alternative to fossil diesel and fully compatible with existing non-road diesel engines.