Abstract
One of the pillars of sustainable development is the mobility, which has significant energy demand. Nowadays in Europe the demand for diesel fuel continuously growing, while the demand for gasoline decreases slightly. Currently, the biodiesel is the biofuel which is blended into the gas oil with the highest amount in case of Diesel engines, which can be produced from different, even waste-derived triglycerides (with transesterification with alcohol). Due to the adverse properties of biodiesel the storage stability of biodiesel/diesel blends have to be examined in detail.
In our experimental work we studied the changes in the qualities of biodiesels produced from vegetable oil which contained various waste cooking oil (waste-derived component) share (10, 30, 50 %), and its 7 and 10 % blends with gas oil in case of long-term (more than 150 weeks) storage.
We found that with the increasing the proportion of used cooking oil in the vegetable oil used as raw material for biodiesel the oxidation reactions took place in greater amount during the storage of the biodiesel product. Biodiesel made from vegetable oils containing 10 % used cooking oil was the most applicable for blending; in case of using higher proportion it is very necessary to use further amount of antioxidant additives to minimize the degradation. The test results suggest that without the addition of additives the biodiesels are not allowed to store longer than six months, and the diesel-biodiesel blends are not allowed to store longer than 1 year. We established mathematical relationships which describe well the relationship between the Rancimat induction period and the kinematic viscosity and the acid number in case of the investigated biodiesels.
