Pellet stoves burn small fuel pellets that look a bit like rabbit feed but are made from waste compressed sawdust. Pellet stoves have augers than continusouly feed fuel into the small combustion chamber where a high airflow burns the fuel at a very high temperature. A fan blows over the burning chamber to quickly moves the heat into the room. They usually have a "low-med-hi" setting which controls how often the augers feed fuel into the burn chamber. These are very efficient, there is almost no smoke and the fuel is cheap - $4.50 a 40lb bag which lasts about a day in a 3000sq ft house. At this time of writing the fuel is about 5x cheaper than oil for the same amount of heat but unlike logs is clean and convenient. In Europe truck deliber bulk fuel pellets bu the ton thorugh a giant hose into a bin. Pro: cheap to run, heats up quiclkly, almost no smoke, simple chimney. Con: expensive to buy, not silent, require electricity to run.