When you friends argue back and you can list hundreds of reasons why and how;
a) The stuff they're drinking is bad for them
b) It would indeed make a better alternative fuel source
c) You would go through a fermentation process using yeast
When you drive past Newcaslte Harbour and identify what the ships are likely to be leaking into the water
You see the signs "Deformation due to Mine Subsidence" and the "When you see a hole, don't think you're a mole" ads on TV and immediatly think of the effects the burning of the mined fossil fuels have on the environment, you list better fuel sources in you head and compse equations for combustion
You go past the old sulfide works on the train and compose a list of all the waste products that leaked into the soil, air and water when it was still used as a lead smelter.
You watch crime shows and know that the techniques they are using to gather evidence are wrong. And that Luminol, the substance used to make blood show up, will kill you in the large amounts these shows use it in.