How does a wood-burning stove impact upon the environment?

Combustion is a chemical reaction defined by the release of carbon dioxide and water. When wood is burnt it releases water in a gaseous state, such as steam, and carbon dioxide. Though a wood burning stove may not heat up as fast as an electric stove, it may release less carbon dioxide. Obviously an electric stove does not use combustion, but the electricity we use is usually sent along wires from an industrial plant that does use combustion. Some of this electricity is lost in the process of travel to your house and stove. Therefore it would be more efficient, carbon dioxidally speaking, to use a good wood burning stove as opposed to an electric one. The reason most wood burning stoves have been replaced with electric ones is for economic efficiency. Electricity is most often cheaper than good fire wood.

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The use of wood in a wood stove can make heating more efficient than use in a fireplace, but it also can increase the amount of atmospheric pollutants, if it is done without consideration for the environment.

The use of wood as a fuel can have positive or negative effects on the environment, depending on how it is done. There is a link below to a related question dealing with the broader issue of using wood as fuel.

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A clarification - wood stove, wood burning heater and fireplace are not equivalent terms. Usually the wood burning heaters (at least modern ones) use pelleted wood and good control of heat and combustion air to ensure as good a combustion as possible. Wood stoves often use wood as sticks or billets to burn, and a wood fireplace is essentially open burning in a non enclosed are with a smoke removal system.

All of these systems produce some smoke and unburned hydrocarbons which, in an urban environment, are not well dispersed. This causes a buildup of contaminants in the area which may aggravate Allergies or Asthma, or cause soot and staining at neighbors' locations. There is also a characteristic odor which may interfere with what is called the quiet enjoyment of property in legal circles.

With the exception of the pellet burning heaters, the robust fuel requirements of wood burning heaters leads o the inclusion of preserved woods (containing heavy metals and chlorinated phenolics), painted wood (heavy metals) and plastic in the fuel mix. There is also a temptation to burn scrap paper, plastic, wet wood and similar items which create more smoke and odors.

Wood burning equipment produces ash which must be disposed of as a solid waste. If allowed to become wet, ash liberates caustic leachate which is detrimental to soil and groundwater.