Wood pellets are made of highly compressed waste sawdust by-product. They can be used to produce heat in a specially designed stove or boiler. In addition, some existing solid fuel and oil boilers can be converted to make use of wood pellets.

Due to their low moisture content (about 6% to 10%) pellets have a high energy content, similar to high quality coal. Only minor energy losses are experienced burning off the moisture content.

The use of wood pellets for heating is well established in countries such as North America, Sweden, Austria and Denmark and there is a rapidly growing pellet industry in the UK. Pellets are now produced and/ or imported by a number of companies in the UK.

Choose from the following or scroll down the page to read all of the sections:

• Producing wood pellets
• Burning wood pellets
• Wood pellet heating systems
• Buying wood pellets

Producing wood pellets

Wood pellets for fuel are mostly manufactured from waste products from sawmills and other wood processing industries. The materials used include ground woodchips produced from off cuts and waste wood and dry sawdust by-product. No chemical additives are needed, the natural lignin of the wood itself serving as a binder. With smaller pellet presses, which cannot achieve the same degree of pressure as larger ones, small quantities of natural binders are added as well.

Pellet equipment sales in the UK are increasing and tied to the rate of growth is the price and availability of pellet supply. There is now an emerging wood pellet fuel industry in parts of the UK-focussed around pellet production. There are a growing number of medium and small size plants now starting production.

There are currently three main routes to setting up pellet production in the UK.

1. Purpose built 'large scale' wood pellet facility

Large scale pellet production plants may only be appropriate in a limited number of situations in the UK due to variations in local supplies of biomass material suitable for pelletising. Reliable supplies of local, good quality sawdust or other waste wood suitable for processing are essential.

2. Conversion of animal feed or grass mills

This option represents a relatively low cost way to set up pellet production since most of the machinery and auxiliary equipment (including driers) already exists.
Grass has similar characteristics to wood for pelletisation and as grass mills are used only from April to October they offer a good opportunity for wood pellet production during the winter.

Other advantages to this approach are that it would need a relatively low capital cost - especially as production of wood pellets could start modestly and increase as market demand grows. Some disadvantages could be that grass/animal feed pelletising equipment has a lower output rate than machinery specially designed to pelletise wood. Modifications to method and material handling would be needed.

3. Small scale pellet machines

The advantages of this approach to pellet production are that it allows for relatively low capital cost, there is a fairly low power requirement (50kVA supply) and there is a short project set up period. Delivery is 10-12 weeks, commissioning 2-6 weeks. Total project 12-18 weeks from order.

The typical cost for fully installed and commissioned system 'pellet factory' is between £75k-95k depending on options. Typical production output is 250-300kg per hour, and often it is possible to run the plant on 24 hour shifts, giving a capacity of 1,500 – 2,000 tonnes per annum.

With small scale pellet production it is easier to find a supply of raw material locally and to supply pellets more locally, keeping both production and transport costs down and ensuring the least environmental impact.

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Burning wood pellets

Being manufactured to a consistent size (usually about 2cm long with a diameter of 6 or 8mm), low moisture content and high density means that wood pellets can be used in automatic clean-burn heating appliances. It also means that the boiler response time is fast and the technology is controllable without increasing the load on the environment.

This and the fact that they are clean and easy to handle make them particularly suitable for domestic use. Being compressed also means that they take up less room than other forms of wood fuel.

Pellets have the following advantages over other types of wood fuel:

• Less volume to transport and store (due to higher energy density)
• Fewer deliveries
• Consistent size and moisture content
• Versatility - can be used in stoves and boilers
• Less ash and emissions
• Pellets are dry and can be stored without degrading
• Flow like a liquid and can be used in automatic machinery
• Easier to handle
• Easier to ignite

The best solution for delivering pellets to a pellet boiler, allowing for easy and convenient pellet handling, is to install a pellet store designed to receive pellets delivered by bulk tanker. The pellet store can be built either outside the house or inside and needs only slightly more space than the equivalent oil or LPG tank if deliveries are scheduled regularly. The pellets are transported to the boiler via special feed systems consisting either of an auger inside a tube or a vacuum transfer system.

The alternative system for the storage of pellets is to buy them by the bag. Although this is more expensive than purchasing pellets in bulk, it is the main method for the delivery of pellets to domestic boilers in the UK at the present time. Purchasing by the bag is the most convenient way of storing pellets to be used in a pellet stove.

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Wood pellet heating systems

Wood pellets are burned in specially designed pellet boilers and stoves, many brands of which are available in the UK – the most well established being the Swedish, Danish and Austrian makes (there are very few UK manufacturers of wood pellet systems). Using a ‘pellet basket’ pellets can also be burnt directly in your existing hearth or solid fuel burner, or even used outside in the garden.

For more information on each application click here

For a list of local suppliers of pellet burning stoves and appliances see our Wood Fuel Directory

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Buying wood pellets

The growth of the wood pellet market will be relative to customer confidence in availability and quality of supply. A pan European standard CEN/TC 335 for biomass is also being developed, under which the fuel specifications and classes for all solid biofuels are set out in CEN/TS 14961:2005.

These are the specifications which customers should look for when buying premium wood pellets:

• Diameter between 6 & 25mm & length = 5 x diameter
• Ash content =0.7%
• Moisture content below 10%
• Calorific value > 4.7kWh/kg (net)
• Bulk density > 600kg/m
• Nitrogen =0.3%
• Sulphur content < 0.08%
• Chlorine < 0.03%
• Additives < 2% natural (from agricultural and forestry biomass, unmodified).
• Durability =97.5% (i.e. less than 2.5% break off as fines under stress-testing)
• Fines =1.0% (at the factory gate)

The cost of wood pellets fluctuates according to supply and demand and such factors as the availability of sawdust, the cost of importing and delivery costs. However the cost of heating with pellets is usually on a par with or better than the cost of oil, LPG or mains gas. As the price of these fossil fuels increase, so too do the economic benefits of using wood pellets. For further information on the cost of wood fuel see fuel costs.

Pellets can be delivered in one tonne loads in sacks of 10- 20kg on a pallet; in bulk bags of up to 1,250kg; or in bulk by blower lorry, in the same way as oil. Pellets can be collected by the bag (more common for pellet stoves as opposed to boilers). Pellets bought by the bag are more expensive and more handling is required.

There are a growing number of suppliers of wood pellets in the UK, including one in Surrey. See our Wood Fuel Directory for local suppliers and the Woodlots directory for South East based suppliers.