[BioQs]

I'm looking to compare fuels based on how environmentally friendly they are. Most reactions I've found involve the fuel + O2, but I want to know how they combine with nitrates when it's more than just oxygen in the air (I'm an Architect with limited background in chem...apologies if this is basic stuff). Here's what I've gathered

Gasoline
2 C8H18 + 25 O2        18 H2O + 16 CO2
Ethanol
C2H5OH + 3O2           2 CO2 + 3H2O + heat
Petrodiesel (Diesel fuel)
C10H20 + 15 O2         10 CO2 + 10 H2O
Biodiesel (ethyl sterate)
C20H40O2 + 29 O2       20 CO2 + 20 H2O

How would adding nitrates found in air effect these?

Additionally, if I looked at these I would think Ethynol has the lowest CO2 emissions, but then notice there are 3O2 on the left whereas Biodiesel's equation has 29 O2 and Gasoline has been multiplied twice to make whole numbers. Is there an acceptable way to standardize equations so that I can compare CO2 emissions without these variables?

[Fleaker]

I consider environmentally friendly fuels as those which burn completely (i.e. no harmful pyrolysis products like polyaromatic hydrocarbons or soot) to water and carbon dioxide and can be sourced in a sustainable manner.

Nitrates aren't found in the air, except near fertilizer factories! You surely mean nitrogen oxides, commonly produced as a side reaction in internal combustion engines (diesel is most notorious for this; ever notice how a city bus's exhaust smells of nitrogen dioxide/nitric acid?)

The equations you've listed give how much CO₂ and water is produced, presuming the reaction goes to completion (i.e. efficient burning). What you do not have listed is how many kJ or kcal of energy are released per mole (or mass unit) of material. Obviously, bigger molecules like long chain alkyls in diesel and biodiesel have more carbon to hydrogen bonds and will have much energy per mole because there are more bonds to break.

Nitrogen oxides present in air would likely not be in concentration significant enough to make much of a different to the efficiency of the fuel. Nitrogen oxides are themselves oxidizers, but of lesser order than oxygen itself (at least the lower nitrogen oxides, i.e. N₂O, NO, NO₂ etc.).

All the reactions you'll find for carbon containing fuels will involve oxygen!

Good luck.