Solid Fuel
There are many different types of fuel suitable for use in solid fuel heating, including wood, coal, coke, peat and fuel tablets (usually hexamine or tiroxane).
Wood
One of the most commonly used solid fuels is wood; often put under the umbrella term of biomass. Wood is predominantly divided into two categories, hardwood (ash, beech, oak, etc) and softwood (mainly pine and fir), and is usually burnt in the form of wood pellets, wood chips, or logs. Wood is often considered to be carbon neutral as trees remove carbon dioxide from the atmosphere and help replenish the oxygen, minimising the impact on the environment caused during combustion.
Advantages of wood include that as it is considered to be 100% renewable, is readily available (so is comparatively cheap), and contains little in terms of traces of sulphur which combusts to form sulphur dioxide and contributes to acid rain. Another advantage is that the consumer may use the ash produced as a fertiliser. For these reasons, wood is very popular as a fuel for solid fuel central heating systems and solid fuel boilers. However, it does not produce as much heat as other solid fuels, namely coal.
Coal
Coal and coke are also fairly commonly used (especially in specialised coal stoves), and coal is also produced to be “smokeless” (anthracite; a hard, dense form consisting of 90% carbon and few impurities). Coal is formed from vegetation crushed under pressure, initially creating peat (which may also be used in solid fuel heating in the form of peat briquettes), which has then been subject to further pressure, producing coal. It has a variety of advantages; it is relatively cheap, burns easily and is readily available, but also has its disadvantages.
Coal, firstly, is non-renewable. This means that we cannot replenish the earth’s supply as we use it, and experts predict that coal will run out in only a few hundred years, though present rates of consumption may increase as other energy sources run out. Also, coal produces a comparatively high amount of carbon dioxide, as well as sulphur oxides and nitrous oxides, which are environmental pollutants. Also, if using the non-smokeless variety, it will be necessary to have the chimney swept twice a year as the residue can cause chimney fires.
Coke
Coke is similar in composition to coal but has the added disadvantage of producing environmental pollutants such as ammonia and coal tar, and is a stronger reducing agent than coal, so requires a greater supply of fresh air. However, it burns at a higher temperature which lowers the amount required. This means that owners of solid fuel stoves in homes or businesses with a small amount of storage space often prefer it to other fuels.
Note – If you live in a smoke control area, the burning of fuels which produce smoke is prohibited; your local authority can advise you further on this, for example on whether or not your area is a smoke control area, and alternative fuels that are permitted.
Solid Fuel Tablets
Fuel tablets, commonly containing the chemicals hexamine or tiroxane, are an example of solid fuels with a high energy density and remain solid throughout the burning process. In addition, they are lightweight and compact, although can be difficult to ignite at first and most types will give off unpleasant fumes. They are also more expensive than other forms of solid fuel.