When corn is burnt completely, three main things are left behind, water ( in the form of water vapor ), carbon dioxide ( CO2 ), and carbon ( the ash left in the fire pot ). Water and carbon dioxide are used by the next corn crop as it grows. Carbon is an excellent soil amendment ( fertilizer ) and good for plants, no matter if used in the home garden or returned to the corn field. Local energy is good for everyone. Not only does it keep transportation ( and its costs ) to a minimum, but it also keeps the money in the local economy. Instead of the money going to people in other countries, it goes to a neighbor, who will likely spend it locally.
Corn is also energy dense. At an average of 8500 BTU per pound, the standard bushel (56 pounds of corn, about the size of a regular laundry basket) has a lot of energy for its price.