In line with the trends toward decarbonization and sustainability across various sectors of life, particularly in the processing industries (manufacturing/process industries), the use of biomass boilers has become a realistic option today among boilers that utilize other renewable energy sources. Fossil-fuel-fired boilers—such as solid-fuel boilers (coal), liquid-fuel boilers (industrial diesel), and gas-fired boilers (natural gas)—must be replaced with renewable fuel boilers, namely biomass boilers. Apart from technical factors in the form of operational adjustments from previous fossil-based fuels, the suitability and availability of biomass fuels are important factors. Suitability refers to the technical aspect and availability refers to the economic aspect.
Combustion technology for biomass boilers also continues to develop so that efficiency continues to increase. From the beginning in the form of static grates to dynamic moving grates such as chain grates and reciprocating grates, even fluidized beds. And to get optimal performance, biomass fuel specifications must also match the shape, size, calorific value and dryness. If the specifications do not meet the requirements of the combustion technology in the boiler then of course the performance will not be optimal. For example, chain grates are suitable for using fuel that has a uniform size and low water content such as palm kernel shells, wood chips and wood pellets. Apart from that, biomass fuel with ash content which has a high melting point is highly preferred so that the ash does not melt and clog the chain lattice cavity.
Meanwhile, using a reciprocating grate, this system is very reliable for burning biomass with high moisture content (up to 60%), non-uniform size, and high ash content, such as empty oil palm fruit bunches (EFB), bark, and municipal solid waste (MSW). The combustion system moves back and forth periodically (like a moving staircase that moves back and forth) which functions to mechanically turn and stir the fuel. And for fluidized beds, this system has the highest thermal efficiency (>89%) and is very suitable for biomass with very small size (powder/dust), low calorific value, or fluctuating chemical content such as rice husks, sawdust, and coffee grounds. The biomass particle size must be maintained within certain limits so that it can float and fluidize perfectly with the sand bed media. The ideal particle size for a fluidized bed boiler (FBC) generally ranges from 0.1 mm to 10 mm (maximum 30–50 mm for certain components), depending on the specific type of technology used.
As a country located on the equator with a tropical climate, Indonesia is a biomass paradise in the world; read more here. A wide variety of biomass fuels in large volumes can be sourced in Indonesia. The most readily available biomass fuels in Indonesia today are wood chips, palm kernel shells, and wood pellets. Wood briquettes are also available but in limited quantities. Choosing the right biomass fuel will ensure optimal boiler performance, but of course, the economic factors for each metric ton of high-pressure steam produced are equally important.
Ideally, biomass fuel is available in large quantities, ensuring affordability and high quality. The price of biomass fuel is influenced by various factors, including availability, location, logistics infrastructure, and transportation costs. Furthermore, if the biomass fuel undergoes processing, such as wood pellets and briquettes, production costs also contribute. Palm kernel shells for industrial boiler use in Indonesia require almost no processing; they are simply collected from palm oil mills or CPO mills, which produce waste in the form of palm kernel shells (PKS).
There is a case study regarding the selection of this biomass fuel involving a multinational company. In a certain country, the company’s boilers operate using wood briquettes—specifically, industrial briquettes produced by a mechanical press. This approach was also planned for the company’s plant in Indonesia. However, because producers of wood briquettes are still very scarce in Indonesia—making it impossible to secure a supply—the company ultimately conducted various experiments and trials with different types of biomass fuels and now operates its boilers using wood pellets. Thus, in addition to technical factors, economic factors are also crucial for ensuring optimal and sustainable biomass boiler operations. The trial phase is a critical step in achieving these conditions.


































