Few more words on edible oil as a fuel
Posted: Wed Feb 03, 2021 9:13 am
Is it technically possible and sensible to use edible oil as a fuel for cars? The shortest answer is yes, but under the right conditions.
To begin with, we need to distinguish between two ways of doing things. The first is to produce the methyl ester of this oil. In a nutshell, it consists of precipitating about 20% of glycerine contained in edible oil and giving it properties similar to mineral diesel. The process is chemically uncomplicated, and small "home" installations are available for this purpose. Such diesel fuel (the so-called biofuel) is absolutely equivalent to mineral diesel fuel, and for several years it has been a 5% or more addition to commercial diesel fuel. There are also some "BIO 100" fuels on sale, i.e. one hundred percent biofuel for types of diesel (economic conditions that result in such an offer is a topic for a separate story). In any case, edible oil esters (in our case, if made from rapeseed oil, they have the international name "RME"), can be used interchangeably in practically all types of diesel engines, especially in modern ones, because they are adapted to this use. This adaptation only involves the use of seals and rubber and plastic parts in the fuel system, which do not react with this fuel. The only limitation is to avoid long, months-long storage of the biofuel, which can decompose over time.
But let's look at the second use of edible oil, which is to use it directly as diesel fuel. Is this possible? Yes. Edible oil is good diesel fuel, even though it has quite different physical and partly chemical properties from mineral diesel. The most important differences from our point of view are as follows:
edible oil has several to several percent lower heating value (relative to volume)
edible oil has a significantly higher viscosity
heating oil has a much higher flash point (over 200 degrees Celsius)
heating oil has a slightly lower cetane number (a parameter determining the self-ignition capacity of fuel mixed with air and injected into the combustion chamber).
So here you go. It is possible. Would I do it? No, no I wouldn't.
To begin with, we need to distinguish between two ways of doing things. The first is to produce the methyl ester of this oil. In a nutshell, it consists of precipitating about 20% of glycerine contained in edible oil and giving it properties similar to mineral diesel. The process is chemically uncomplicated, and small "home" installations are available for this purpose. Such diesel fuel (the so-called biofuel) is absolutely equivalent to mineral diesel fuel, and for several years it has been a 5% or more addition to commercial diesel fuel. There are also some "BIO 100" fuels on sale, i.e. one hundred percent biofuel for types of diesel (economic conditions that result in such an offer is a topic for a separate story). In any case, edible oil esters (in our case, if made from rapeseed oil, they have the international name "RME"), can be used interchangeably in practically all types of diesel engines, especially in modern ones, because they are adapted to this use. This adaptation only involves the use of seals and rubber and plastic parts in the fuel system, which do not react with this fuel. The only limitation is to avoid long, months-long storage of the biofuel, which can decompose over time.
But let's look at the second use of edible oil, which is to use it directly as diesel fuel. Is this possible? Yes. Edible oil is good diesel fuel, even though it has quite different physical and partly chemical properties from mineral diesel. The most important differences from our point of view are as follows:
edible oil has several to several percent lower heating value (relative to volume)
edible oil has a significantly higher viscosity
heating oil has a much higher flash point (over 200 degrees Celsius)
heating oil has a slightly lower cetane number (a parameter determining the self-ignition capacity of fuel mixed with air and injected into the combustion chamber).
So here you go. It is possible. Would I do it? No, no I wouldn't.