Some briquettes are compressed and dried brown coal extruded into hard blocks. This is a common technique for low rank coals. They are typically dried to 12-18% moisture, and are primarily used in household and industry.
In Ireland, peat briquettes are a common type of solid fuel after coal. Although often used as the sole fuel for a fire, they are also used to begin a coal fire quickly without hassle. A fire burning peat briquettes is, similarly to a turf fire, slow burning. Peat briquettes can be used as an acceptable substitute for charcoal in barbecues for this reason.
A number of companies in India have switched from furnace oil to biomass briquettes to save costs on boiler fuels. The use of biomass briquettes is predominant in the southern parts of India, where coal and furnace oil are being replaced by biomass briquettes. A number of units in Maharashtra (India) are also using biomass briquettes as boiler fuel. Use of biomass briquettes can earn Carbon Credits for reducing emissions in the atmosphere. Lanxess India and a few other large companies are supposedly using biomass briquettes for earning Carbon Credits by switching their boiler fuel. Biomass briquettes also provide more calorific value/kg and save around 30-40 percent of boiler fuel costs.
A popular biomass briquette emerging in developed countries is one which takes a waste produce such as sawdust, compresses it and then extrudes it to make a reconsistuted log which can replace firewood. It is a very similar process to forming a wood pellet but on a larger scale. There are no binders involved in this process. The natural lignin in the wood binds the particles of wood together to form a solid. Burning a wood briquette is far more efficient than burning firewood. Moisture content of a briquette can be as low as 4%, where as green firewood may be as high as 65%.
Sawdust briquettes have developed over time with two distinct types: those with holes through the centre, and those which are solid. Both types are classified as briquettes but are form using different techniques. A solid briquette is manufactured using a piston press which simple sandwiches layers of sawdust together, and ones which a hole are produced using a screw press. The hole is simply a by product of the screw thread passing through the centre however it also increases the surface area of the log and aids efficient combustion.