Use of straight vegetable oil mixtures of rape and camelina as on farm fuels in agriculture

Possibilities for using straight vegetable oil (SVO) from Camelina sativa (L.) Crantz (camelina or false flax) and its mixtures with Brassica napus (rape) SVO as fuel in adapted diesel engines are described with chemical parameters, measurements in a test engine and a field test in a tractor. Camelina as a crop is attracting attention in organic farming and is often used in mixed cropping systems with low competition to food production area. Camelina SVO has low oxidation stability. Its polymerization affinity limits the storage time and increase the risk of coking at hot motor components and of thickening processes in the lubricant oil of the engine. In mixtures with rape and camelina SVO, threshold limits for Conradson Carbon Residues and for oxidation resistance were exceeded. The oxidation resistance could be prolonged by the addition of commercial antioxidants. Camelina and rape SVO showed very similar burning characteristics at full-to-medium partial engine loads. Under low partial loads and idle load, the burning function of the various fuels was increasingly delayed, beginning with diesel fuel over pure rape SVO, then a mixture containing 700 dm3 m−3 rape SVO, and 300 dm3 m−3 camelina SVO, through to pure camelina SVO. The exhaust emissions of NOx-, CO-, particles and HC of rape SVO, camelina SVO and their described mixture were not significantly different. The typically higher NOx- and lower HC-emissions of SVO compared to diesel fuel were apparent. The results principally reveal the usability of a cold pressed, non-refined camelina-rape SVO mixture in adapted diesel engines.

► We examined mixtures of farm available straight vegetable oils as biofuel. ► The results are based on chemical analyses, on runs in a test engine and a 1000 h tractor test. ► Oil from Camelina sativa L. crantz and Brassica napus L. were mixed as fuel. ► Principally the mixture can be used as on farm biofuel in adapted diesel engines.