Pellet stoves are easier to keep burning 24 hours a day, so most people are less likely to use their conventional furnace to heat up the house, when you get home from work or wake up in the morning, for example. There are lots of folks who manage to rely only on their wood stove all winter and maybe you are one of them. For most of us, a pellet stove is the best way to avoid using the furnace or boiler periodically through the winter. The production of pellets has a slightly higher carbon footprint than cordwood harvesting and splitting, especially if you split your wood by hand. But the carbon input for pellet production is not large at all, particularly compared to drilling, refining and transporting fossil heating fuels.
Pellet and corn stoves also need electricity to run their blower fans – about 100 kWh per month and that electricity is mainly generated from fossil fuels – coal and gas. Of course, installing a pellet or wood furnace to entirely replace your existing system is likely to reduce your carbon footprint the most, particularly in a larger house and in colder climates.