As a fuel, corn typically provides an annual fuel utilization efficiency (AFUE) rating of 60 to 80 percent, placing it somewhat below natural gas and heating oil, which typically rate between 70 and 95 percent. However, people with access to cheap corn may save money.
Wood furnaces typically have AFUE ratings of approximately 60 percent, so corn provides better energy density. Shelled corn is also easy to pour into a stove or furnace, and corn produces less ash by volume compared to wood. While burning corn produces particulate matter and carbon dioxide, future crops absorb virtually the same amount of pollutant, which makes corn a carbon-neutral fuel source by some calculations.