Rice Husk Briquettes Amid the Soaring Condition of Biomass Fuel Demand

 "Briquettes are a compressed biomass fuel (densified biomass fuel) as an alternative to pellets."

The use of biomass energy is increasing day by day so this is a positive thing that needs to be encouraged. The increase in coal prices (domestic industry is priced at $90) and the resulting pollution are especially the driving force for energy use from the biomass. Among biomass energy, wood pellets are the most popular and most widely used form of biomass fuel. The use of wood pellets is not only used by processing industries but also by power plants. A number of small and medium industries such as tofu factories, cracker factories, and so on. Wood chips, as a simpler form, are less attractive than wood pellets, even though they are cheaper. With a low density, the transportation costs are also high, besides that the moisture content of wood chips is sometimes also less controlled.

The form of briquettes is also less popular than wood pellets. Briquettes can also be said as an alternative to pellets. The technology for making briquettes is the same as wood pellets, namely biomass densification, the difference is that the size of the briquettes is larger than wood pellets. Unlike wood pellets, which only use roller press technology for their production, briquettes have several variants of technology for their production, for more details, read here. But in Indonesia there is only one type of briquette, namely the screw press. Indeed, in many ways briquetting is easier than pelletizing. Biomass materials that are difficult to pelletize are usually easy to briquette. Certain types of boilers may also be more suitable for briquettes, compared to wood pellets, read in more detail here. Therefore, the use of briquettes should also be encouraged.

In addition to wood waste, agricultural wastes are also potential biomass for fuel. Rice husk is an abundant agricultural waste because the staple food of Indonesians is rice. It is estimated that the amount of rice husk is 15 million tons/year. However, with the high content of ash and silica, this rice husk is less desirable to make pellets because it is abrasive, thus shortening the service life of machine components. Likewise for making briquettes, but with a variant of the mechanical press technology, the abrasive problem can be minimized. The production of rice husk briquettes with mechanical press technology can be a solution for the utilization of the rice husk waste. In the midst of the increasing use of biomass fuels, rice husk briquettes can be the next alternative.

Rice Husk Pellets or Rice Husk Briquettes?

 

Rice husk truck, photo taken from here

Indonesia's rice production in 2008 is estimated to reach 59.9 million tons of milled dry unhulled rice with a composition of 25% husk, which means that the potential for husks reaches 15 million tons / year. Although the amount is abundant but generally the utilization is still not optimal, this is because the rice husks have low bulk density and low calorific value due to the high ash content. So that the rice husks can be utilized optimally, one solution is densification. With this compacted rice husks can be easier to use, economical in transportation and facilitate storage. A large pile of rice husks also has a strong tendency to burn. The dry husks easily fly like dust so that high concentrations in the room will be flammable and dangerous. Compaction of rice husks will make rice husks larger, denser and heavier so that they do not fly easily or in other words, reduce the risk of the fire.

The need for biomass fuel has increased recently. This encourages the use of agricultural and wood processing industrial wastes. These wastes were initially not utilized and tended to pollute the environment, but now they are being processed a lot for the production of biomass fuels. A positive effort, of course, because in addition to minimizing environmental problems caused by waste, it is also a profitable business activity. Production of biomass fuel can start from medium capacity to large capacity, from a capacity of several hundred tons or thousands of tons per month to hundreds of thousands of tons per month. Although the potential in Indonesia is large, generally the use of these wastes is not maximized so that commercial biomass fuel production is generally still low. 

 Briquettes and pellets are the products of the biomass densification technology. Basically, briquettes and pellets have their own characteristics, although physically they can be easily recognized by the size of the briquette that are bigger than the pellets. The briquette technology is also more diverse than pellets, so that is the case with the output in the form of the briquette product, for more details, please read here. For rice husks for use as industrial fuel, industrial production of briquette with a mechanical press is most suitable. This is because it is technically easier and economically cheaper. Although the rice husk can also be pelleted, it will cost more. This is because rice husks are very abrasive due to the large ash content with the main constituent component in the form of silica. The ring die and roller press on the pelletiser will wear out quickly due to the abrasive material. Production of rice husk briquettes with a screw extruder is also possible and possible, even a number of countries such as Pakistan, Nepal, Bangladesh, Vietnam and Thailand have also done so. But with these abrasive materials the production costs are also high. The briquettes produced by the screw extruder are also long so they usually need to be cut into pieces for use so that the use of the screw extruder also becomes less practical. With a mechanical press, the briquette size can be cut into small pieces easily, making it easier to use.