Ethanol does not release carbon into the atmosphere via combustion.

Ethanol does not release carbon into the atmosphere via combustion.

• A. False
• B. It releases carbon dioxide but not carbon monoxide
• C. Only methane is released
• D. True

Answer: (D)

Think about carbon in a cycle. The carbon in ethanol comes from atmospheric CO2 that plants fixed while growing. When ethanol burns, that same carbon is released as CO2 (and water), so no new atmospheric carbon is added in the short term—the carbon just returns to the air it came from. That’s why, in discussions of biofuels and carbon cycles, ethanol combustion is often described as not adding new carbon to the atmosphere, even though CO2 is produced chemically. Real-world factors like processing energy and transport can add emissions, and incomplete combustion can produce small amounts of CO, but the basic idea is that the carbon released during ethanol combustion is biogenic and part of a short-term carbon cycle.

Think about carbon in a cycle. The carbon in ethanol comes from atmospheric CO2 that plants fixed while growing. When ethanol burns, that same carbon is released as CO2 (and water), so no new atmospheric carbon is added in the short term—the carbon just returns to the air it came from. That’s why, in discussions of biofuels and carbon cycles, ethanol combustion is often described as not adding new carbon to the atmosphere, even though CO2 is produced chemically. Real-world factors like processing energy and transport can add emissions, and incomplete combustion can produce small amounts of CO, but the basic idea is that the carbon released during ethanol combustion is biogenic and part of a short-term carbon cycle.