Question

In some countries, ethanol is used as an additive to increase the efficiency of petrol.

Hint:

Ethanol-blended fuels not only improve efficiency but also help reduce the carbon footprint of fossil fuel-based transportation.

Answer 1

Ethanol is often added to petrol to improve its combustion efficiency and reduce harmful emissions. There are two main reasons for this:
High Octane Rating: Ethanol has a high octane rating, which measures a fuel's ability to resist "knocking" or "pinging" during combustion. A higher octane rating allows the engine to use a higher compression ratio, leading to greater thermal efficiency and better engine performance.
Oxygenate: Ethanol is an oxygenated fuel, meaning it contains oxygen in its molecular structure. This additional oxygen helps the petrol to burn more completely. Complete combustion reduces the emission of harmful pollutants like carbon monoxide (CO) and unburned hydrocarbons.
In addition to improving combustion efficiency, ethanol is a renewable biofuel, typically produced from crops like corn or sugarcane, making it a more environmentally friendly alternative to purely fossil-fuel-based gasoline.