The transition from fossil-fuel-based heating systems to climate-neutral alternatives is a key measure for mitigating climate change. In addition to the use of heat pumps, sustainable synthetic heating oils represent a viable option, as they largely make use of existing infrastructure and require only minimal adjustments. However, for their widespread adoption, it is crucial to understand how conventional fossil and synthetic paraffinic heating oils—in particular Fischer-Tropsch (GtL) and hydrogenated vegetable oils (HVO)—behave when blended and how they age.
The fossil and synthetic heating oils examined differ significantly in their molecular composition: While synthetic products consist primarily of saturated paraffinic hydrocarbons, fossil heating oils contain complex mixtures of cyclic, aromatic, and unsaturated components.
Over a period of 18 months, pure products and mixtures were aged under idealized storage conditions and subsequently analyzed. Both standard analyses and detailed analyses were performed. The results show that aging and degradation processes occur in all samples, albeit to a limited extent. In technically simulated application tests, these effects were significantly more pronounced, particularly in mixtures containing fossil-based components.
These results suggest that all heating oils undergo oxidation processes and potential oligomerization reactions, albeit at different reaction rates. Fossil heating oils are more prone to forming solid precipitates, which is relevant for the operation of heating oil tanks. Synthetic heating oils such as GtL and HVO, on the other hand, exhibit increased oxidative stability. This suggests that sustainable paraffinic heating oils represent a suitable and stable alternative for future non-electric heating applications and can generally be blended with conventional heating oils without increasing the formation of undesirable deposits.