For what reason is methanol added to the propane fuel of hot air balloons?

• A. As an anti-icing additive
• B. To increase combustion efficiency
• C. To decrease vapor pressure
• D. To reduce flame temperature

Answer: (A)

The main idea is preventing ice from forming in the fuel system. In cold, humid conditions the propane flowing through regulators and lines can cause water in the system to freeze when the gas expands and cools, leading to ice blocking flow or clogging valves. Adding methanol to the propane acts as an anti-icing agent: methanol stays liquid at lower temperatures and helps keep moisture in solution or absorb it, reducing the formation of ice in the fuel lines and regulators. This keeps fuel delivery smooth and the burner operation reliable. It’s not about boosting combustion efficiency, changing vapor pressure, or lowering flame temperature—the icing risk is what this additive addresses.