(Aspen) Alkylate fuel for camping stoves and lanterns

Aspen fuel is marketed for usage in small gardening machines like chainsaws and lawnmowers. Lesser known is that it is a excellent fuel for camping stoves and lanterns. It burns fiercely without any smell.

Aspen fuel is a brand of so called Alkylate Petrol. This type of petrol is made by a synthesis process instead of distillation. The result is a very pure fuel that is free from hazardous components that naturally occur in fossil oil. Usage is very popular in machines that are used outdoors such as chainsaws, hedge trimmers, lawnmowers, vibratory plate compactors for pavement construction etc. When used professional alkylate fuel is often demanded by health and safety regulations. When used in petrol stoves as a replacement for white gas you can benefit from the same clean burning characteristics. Reports of usage indoors without odor problems are not uncommon.

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The so called alkylation process was developed in the 1930s and 1940s to initially produce high-octane aviation gasoline. Nowadays it is used in oil refining plants to produce high-octane number blending components for automotive gasoline. Swedish chemist and fuel expert Roland Elmäng developed a fuel based on this process during the 80’s for usage in chainsaws. This in order to improve the working conditions of wood choppers working in the tree logging industry. Headache were a common discomfort among the operators of chainsaws and scientific reports about elevated rates of cancer (leukemia) started to emerge. The Aspen company was founded in 1988 on the shore of lake Aspen, north of Gothenburg, in Sweden. Nowadays the usage of Aspen fuel in chainsaws and other machines is often obligated by health and safety laws for professional usage in many countries. 

Chemical background
Alkylation in oil refining is a chemical process in which small gaseous molecules are combined into larger molecules. These gasses can be found in the top of the distillation tower. Usually Isobutane (C4) is combined with Propane (C3) or Butane (C4). Resulting in larger molecules that are liquid. Standard White gas such as Coleman Fuel or Crown Camp Fuel is made through different processes (hydrocracking) in where the starting material is liquid petroleum that is treated with hydrogen. It consists of molecules with a carbon chain length in the range of C5-C9. The Materal Safety Data Sheet of Coleman® Camp Fuel lists Pentane, Cyclohexane, Heptane, Octane and Nonane. Although not mentioned in the MSDS it is likely that traces of so called BTX are also present; Benzene (C6), Toluene (C7) and Xylene (C8). (All liquids at normal temperature and pressure) These are often referred to as aromatic compounds. These compounds are highly toxic. Even the smallest amounts in the air by incomplete burning will cause instant headache. By starting with gaseous molecules that have less C-atoms then 6, the liquid benzene rings are completely avoided. Furthermore the reaction mechanisms that break the double bounds in isobutene and propene will also break the aromatic rings. Hence the extreme low aromatic compound content in Aspen Fuel. The Materal Data Safety Sheet of Aspen 4 mentions “Benzene level lower than 0,1 %”. That’s 20 times less then the <2% aromatic compounds mentioned on most other petroleum products. The difference can be smelled when sniffed on the bottle. Aromatic compounds have a distinct smell, often experienced as pleasant. A bottle of Aspen Fuel has a totally different smell, more close to butane or butanol. This can easily be explained as Butane was the starting material and will most likely dissolve partially in the liquid that is formed. The MSDS (Revision 09.07.2018) also mention a content of n- Butane 0- 4%.  

Side note: Camping gas canisters contain mixtures of Propane and Butane. One of the reasons camping gas canister stoves gained so much popularity over liquid fueled camping stoves is that they virtually burn without any smell. Alkylate fuel also burns virtually without any smell. No wonder since that is made from the very same gasses that are use in camping gas canisters !.

Aromatic compounds.
Benzene rings (aromatic compounds) and the double bounds in some molecules are very reactive and often used as the starting point for chemical reactions. One of them is polymerization; the conversion of smaller molecules into extreme large molecules. The absence of these is what gives Aspen Fuel a very long shelf life. Standard automotive fuel is known for ”gumming up” when left in a machine for a few months. For example lawnmowers often have difficulties in restarting after standing still during the winter months. This is caused by spontaneous polymerization of the olefinic hydrocarbons (double bounds) and or aromatic hydrocarbons (benzene rings). 
Another characteristic of aromatic compounds is that they are very good solvents. Rubber O-rings and flat washers are harmed by this. Often the solvents are causing swelling of the rubber material. The sealing properties are then often lost. Since most camping stoves and lanterns rely on pressure they stop to functioning since the pressure is leaking away through the damaged O-rings and flat washers. That’s why suppliers of camping stove and lantern parts such as Fettlebox UK prefer Viton ® (a brand of FKM rubber) over more standard rubber as NBR in liquid fuel camping stoves. Besides rubber also other polymers are harmed by aromatic compounds. Aspen likes to demonstrate this by exposing porous polystyrene to standard automotive fuel and to Aspen Alkylate fuel. The polystyrene flocks in standard automotive fuel are completely dissolved withing seconds. The polystyrene flocks in Aspen alkylate fuel are unharmed.   

https://www.youtube.com/watch?v=j–t0bBD2Qc

This user reports that the Aspen fuel is burning so cleanly that soot was removed from his stove instead of formed.

More User Experiences:
Classic Camp Stoves forum – Aspen 4 – works a treat
UKcampsites.co.uk 1
UKcampsites.co.uk 2

Conclusion:
Camp fuels are still marketed as a alternative for unleaded fuel. Now the last country in the world, Algeria, has stopped using automotive fuel with lead containing additives in 2021 it is time to move to a new era in camp fuel. Alkalyte fuel is a much healthier alternative over hydrogenated petroleum distillate (the main ingredient in white gas camp fuels). By using Alkylate fuel the odor level is at the same comfort level as camping gas such as Iso butane /propane.

More info:
www.wikipedia.org
www.campingmaniacs.com
threepointsofthecompass.com
Petroleum Processing Alkylation
Aspenfuel.co.uk