We have talked at some length in previous articles about the fact that wood burning stoves are an exceptionally clean, and environmentally friendly way to heat a home.
This article looks at the more technical elements of wood burning stoves, and why they have become such an efficient, green energy source.
Pyrolysis – Pyrolysis is a thermochemical decomposition of organic material at an elevated temperature, with the absence of oxygen. Wood undergoes pyrolysis at 280C, where gases are released from wood and leaves charcoal, ash or carbon behind.
Heat Energy – Around 60% of heat energy in wood is contained in organic gases, which are initially released as smoke when wood burns.
When wood is heated up it releases gases and leaves behind the carbon. As mentioned above, this is called pyrolysis and is a thermochemical reaction, which occurs at a temperature of 280C.
When it comes to designing a stove, our designers have been faced with a challenge as wood burns as both a gas and a solid. To achieve such an efficient, environmentally friendly source of heat, a number of elements are incorporated into the design of the stove, which include:
1. Creating a high enough temperature, which allows the gases to ignite
2. Allowing the gases enough time in the right conditions so they can burn
3. Creating enough turbulence so the gases and oxygen successfully mix together
4. Supplying enough oxygen to meet the combustion reaction, but not so much that it cools the gases
It really is a tightrope in creating an efficient stove design, to ensure that the various elements work together in complete harmony. A slight error or flaw in design would reduce the overall efficiency of a stove, which means a lower heat output, and a lower efficiency stove.
Burning the Right Fuel:
Despite the very best stove design, using a poor fuel can dramatically reduce efficiency. Read our guide to burning wood here for more information on what wood you should and should not burn.
One major issue with wood, even if you are burning the best quality available for a stove, is excessive water. Fresh wood can contain over 50% water. So a 1kg log could contain over 500ml of water. Burning wet (or unseasoned wood) should be avoided at all costs. Read more about the dangers of burning unseasoned wood.
Wood should have a moisture content of around 20%. You can test this with a moisture meter. Read more about the benefits of a moisture meter.
Wood that is too dry can also be problematic. Overly dry wood will burn very quickly and at a higher temperature. This will cause problems with the oxygen level in a firebox. A high temperature will speed up the thermochemical reaction of pyrolysis. This will mean the gases created from pyrolysis will be too much for the oxygen in the firebox, which will prevent a total combustion of the gases. If the gases are not burned they will increase smoke and pollution.
The Benefits Are Clear…
More people are starting to realise the significant benefits that come from using a stove. You are able to view our range of stoves, download brochures and read more about life with a stove in our dedicated stove section on this website – Visit our stove section.