The burning of biomass for energy produces heat at relatively low cost but also produces

• A. Carbon dioxide, carbon monoxide, nitrogen oxides, particulates, and volatile organic compounds
• B. Only oxygen
• C. No pollutants
• D. Only water vapor

Answer: (A)

When biomass is burned for energy, energy is released as heat, but the combustion also releases a variety of substances into the air. The process converts carbon in the biomass into carbon dioxide, and if the combustion is not perfect, carbon monoxide can form. High flame temperatures can generate nitrogen oxides, which contribute to smog and acid rain. Tiny solid or liquid particles—particulates—from the burning fuel, and volatile organic compounds released from organic matter, are also emitted. Water vapor is produced as part of the combustion, but it is not a pollutant in this context. Oxygen is consumed rather than produced. So the typical emissions include several pollutants: carbon dioxide, carbon monoxide, nitrogen oxides, particulates, and volatile organic compounds, making that broad list the best description of what burning biomass releases.