[Tatti45]

Need to design an experiment where to test which one of these is ecofriendly, gasoline, methane and diesel, we could tell  by production of co2, which is less harmful on environment but how do i design that experiment? I thought of combustion but wouldnt be harmful doing in lab?

[Enthalpy]

Welcome, Tatti45!

You could first check how you're supposed to translate "eco-friendly".

The CO₂ amount at identical heat can be measured and compared. Reasonably simple to experiment, report and argue.

There would be if and but already here. For instance, propane and butane are too cheap to transport and torched at the production well, so consuming them rather than others would be the best choice among hydrocarbons. Other example: the same amount of gas oil produces as much CO₂, but Diesel engines consume less than gasoline engines so they release less CO₂. Still an other example: hydrogen produces no CO₂ at the end use, but its production does presently.

Then, you have all pollutants other than CO₂: nitrogen oxides, fine particles, unburnt hydrocarbons... It's all the present fuss against Diesel engines, which emit less PM10 than gasoline but more nitrogen oxides. This is impossible to reproduce in a lab, demanding a real engine with all its filters and control software. Every detail counts here.

So if you measure the CO₂ amount, just burn the fuels. I don't grasp the "harmful" interrogation: have you never burnt a fuel? One difficulty is to bun gas oil properly, because it may soot, and because its flash point is usually above room temperature. Use a wick, or pre-heat the liquid and compute away the added heat. The other is to measure accurately the released heat.