Petrodiesel vs. Biodiesel

[tbhstudying]

Hello everyone,
I was wondering, when the textbook just mentions "diesel" or "petrol", which fuels exactly is it referring to?
For example, here is a quote from the texbook: "There is considerable debate about which fuel, diesel or petrol, is the cleanest in terms of emissions. Diesel engines...... but petrol engines.....".

When it talks about diesel, is it referring to both biodiesel and petrodiesel? What about when it says petrol? Does petrol include petroleum (are they the same thing? :/) and Liquified Petroleum Gas (LPG)? Is petrol just an umbrella term or am I missing something here?

The textbook also says: "Biodiesel exhaust contains up to 20% less particulate matter than diesel." What does this mean? Is it saying that biodiesel exhaust contains up to 20% less particulate matter than petrodiesel? I was thinking it may mean it contains less particulate matter than diesel FUEL as an umbrella term (considering it's a renewable fuel and so is better environmentally). Would I be correct in assuming this?

Also, in the textbook it mentions "crude oil (petroleum)". Does this mean that crude oil and petroleum are the same things? I thought petroleum was what is found in crude oil after fractional distillation.

Hopefully I make sense, any help clarifying the distinctions between all the fuels would be much appreciated.

[sophomania]

In the VCAA study design, one of the points of study is a comparison between biodiesel and petrodiesel as fuels, or more specifically, "The comparison of the suitability of petrodiesel and biodiesel as transport fuels with reference to sources, chemical structures, combustion products,  ow along fuel lines (implications of hygroscopic properties and impact of outside temperature on viscosity) and the environmental impacts associated with their extraction and production".

Knowing this, when the textbooks are comparing biodiesel and diesel, I would assume that they are in fact comparing biodiesel and petrodiesel.

From what I understand, (someone correct me if I'm wrong), diesel is an umbrella term that refers to both biodiesel and petrodiesel. Also yes, petroleum comes crude oil. Also, petroleum diesel is the same as petrodiesel, and is made up of long alkanes and aromatic hydrocarbons. LPG (liquefied petroleum diesel) refers to mostly propane and butane mixtures that also come from crude oil. Basically both petrodiesel and LPG come from crude oil and are separated by fractional distillation. They just contain different alkanes.

[Yertle the Turtle]

In general when it speaks of 'diesel' it means petrodiesel and when it uses 'petrol' it means petroleum. To clarify, LPG is 'liquid petroleum gas', not liquified petroleum diesel. Diesel refers to a family of fuels that includes biodiesel and petrodiesel. Petroleum comes from crude oil, but that is not all that crude oil is. Crude oil is a substance that is refined at different temperatures to separate out the component chemicals such as petroleum, butane, propane, LPG, etc.

[Vaike]

Hi! Fuel choices is a really confusing topic, both in that most resources fail to make key distinctions, and that in the study design is a little bit vague, leading to confusion. I know I certainly had to spend a lot of time to figure this all out last year, so hopefully this will help clear things up.

I think it would be helpful if we defined various fuels you've mentioned.

Diesel: Diesel fuel in general is any liquid fuel used in diesel engines, whose fuel ignition takes place, without any spark, as a result of compression of the inlet air mixture and then injection of fuel (Wikipedia). Diesel is indeed an umbrella term that can refer both to petrodiesel (petroleum diesel) and biodiesel. In general, both types of diesel have similar (not identical) emission characteristics, and if the word 'diesel' is mentioned in comparison to petrol, I'd say it's safe to assume it just means diesel in general.

• Petrodiesel: Also known as petroleum diesel, is produced from the fractional distillation of crude oil, resulting in a mixture of carbon compounds generally containing between 8-21 C atoms.
• Biodiesel: Also known as Fatty-acid methyl ester (FAME), biodiesel is produced from plant oils or animal fats which have undergone a transesterification reaction with methanol.

Petroleum: Is a pretty confusing term, because it can it can refer to natural and unrefined crude oil (basically another word for crude oil), but it can also refer to the products of refined crude oil, such as petrol (which is known as gasoline in other countries such as the U.S). In general, I'd suggest acknowledging petroleum = crude oil.
Petrol: So petrol is essentially a product of fractional distillation of crude oil/petroleum. It can contain alkanes, cycloalkanes and and alkenes from C4-C12, although commonly in VCE questions, petrol is considered to be octane.
LPG: Also mainly derived from crude oil/petroleum, as sophomania mentioned is essentially a (gaseous) mixture of propane and butane.

Honestly, I don't think you really need to know all of this in detail, but it doesn't hurt just in case. Hope this makes some sense

[tbhstudying]

Ok thanks for the clarification everyone!!

[TheAspiringDoc]

• Petrodiesel: Also known as petroleum diesel, is produced from the fractional distillation of crude oil, resulting in a mixture of carbon compounds generally containing between 8-21 C atoms.

Hey Vaike I read in the connect education notes that petrodiesel "is composed mainly of alkanes that are 10-13 carbon atoms long" - do you think 8-21 would be a safer value to use?
Thanks 

[Vaike]

Hey Vaike I read in the connect education notes that petrodiesel "is composed mainly of alkanes that are 10-13 carbon atoms long" - do you think 8-21 would be a safer value to use?
Thanks 

Hi TheAspiringDoc,
I just pulled that value from Wikipedia; I'd suggest using the value provided in your notes or whatever it says in the textbook. I can't really imagine this ever being directly assessed as there is such a range of information out there (petrodiesel from different sources may have different alkanes), so don't stress about it.