Biodiesel from Used Cooking Oil: Is the Pollution Lower?

[Stephanus]

Dear PF Forum,
I have searched biodiesel through internet. There are good answers there.
And also in Physics Forum, and I come across these two links from PF Forum, which are a very good links.
http://biodiesel.org/
http://nbb.org/
And I also consulted LIPI (Indonesian Science Establishment).
The pollution from Bio diesel vs petrolium oil is better.
And also the carbon cycle that they explained there makes sense for me (at least I can follow their explanations if not understand them).
My church wants to help the environment by converting used cooking oil to biodiesel.
And that leaves me with this one question.
1. Is the pollution generated from cooking oil is less than gasoline?

Actually I have other question, too
Some of the internet links say that (even) pollution from biodiesel are higher than gasoline, but because of making biodiesel from plants, the plants have already converted CO2 to hydrocarbon.
2. Is it true that CO2 emission per joule from biodiesel are higher than gasoline?And the conclusion from question 2,
3. Is the pollution from used cooking oil biodiesel is higher than gasoline?
4. If it is YES, than in net, the pollution from used cooking oil biodiesel is actually lower because of carbon cycle?

Thanks for any replies.
I've been searching this answer for 2 months, and those are the questions that I haven't got the answer, yet.

 

[DrClaude]

I don't know the answers to all your questions, but the main point in the use of cooking oil biodiesel is that it is carbon neutral. AGW is due to the fact that all that carbon that was sequestered underground in the form of oil and gas has been converted to atmospheric CO₂. Cooking oil is based on plants, meaning that the CO₂ released when burning was previously in the atmosphere, absorbed by the plant as it grew.

 

[Stephanus]

I don't know the answers to all your questions, but the main point in the use of cooking oil biodiesel is that it is carbon neutral. AGW is due to the fact that all that carbon that was sequestered underground in the form of oil and gas has been converted to atmospheric CO₂. Cooking oil is based on plants, meaning that the CO₂ released when burning was previously in the atmosphere, absorbed by the plant as it grew.

So, that is the main point? Carbon neutral.
I know that making biodiesel from plant is, what you call carbon neutral. So does used cooking oil?
I'm afraid that there are some dangerous chemical in (used) cooking oil than plants. Because cooking oil is preprocessed before, and used cooking oil has more dangerous chemical in it.

Thanks Dr Claude for your answers tonight (night here) and for the noble gas question.
So, basically biodiesel from used cooking oil is safe and less pollution than gasoline?

 

[aikismos]

So, that is the main point? Carbon neutral.
I know that making biodiesel from plant is, what you call carbon neutral. So does used cooking oil?
I'm afraid that there are some dangerous chemical in (used) cooking oil than plants. Because cooking oil is preprocessed before, and used cooking oil has more dangerous chemical in it.

Thanks Dr Claude for your answers tonight (night here) and for the noble gas question.
So, basically biodiesel from used cooking oil is safe and less pollution than gasoline?

The question of pollution is broad. For instance, how you combust has a major effect on your byproducts, so it depends on your method. For instance, a leaky, old diesel engine will leak more pollution than a state-of-the-art, high quality gasoline engine with a sophisticated ECM and pollution controls like EGR and high-efficiency catalytic converters. Also, there are various grades of gasoline, for instance with additives and octane variances. Here's a quick link to point you in the right direction: (http://auto.howstuffworks.com/fuel-efficiency/fuel-consumption/diesel-fuel-better-environment.htm)