Biomass pellets are a form of renewable energy that is considered an efficient alternative to the rapidly decreasing fossil fuels, which are expected to be depleted within the next few years. The decline in fossil fuel usage also contributes to the rise in greenhouse gas emissions, prompting the search for alternative energy sources. Biomass pellets, also known as fuel pellets, offer a cost-effective solution for energy production. These pellets can be utilized in various ways, such as generating thermal energy for residential purposes, producing steam, or serving as fuel in electricity generation through boiler systems.
What is Biomass Pellet Fuel?
Biomass pellet fuel is derived from biomass materials, which encompass agricultural waste like cassava rhizomes, rice straw, corn cobs, wood waste, sawdust, rice husk, bagasse, coconut husks, Napier grass, and more. These materials are dried to remove moisture, then ground into small pieces. Subsequently, they are fed into a biomass pellet press machine, which shapes them into round, high-density bars resembling fuel pellets. (Density is approximately 650-700 kilograms per cubic meter) This high density allows for efficient transportation, as the fuel occupies less volume while delivering higher heat energy. Biomass pellets can be used as fuel in various industrial plants that require firewood, as they provide a natural and renewable energy source capable of generating unlimited energy. The production of pellet fuel offers flexibility in terms of styles and varieties.
Types of Pellet Fuels
Pellet fuel or biomass pellets can be classified into several types based on different criteria:
- Types of pellets based on the biomass used in production include wood pellets and non-wood pellets, among others.
- The type of fuel pellets can be categorized based on their source, such as biomass pellets from industrial waste, biomass pellets from energy crops, biomass pellets from food waste, biomass pellets from agricultural waste, and biomass pellets from processed wood.
- Another way to classify pellet fuels is based on their utilization, which includes biomass pellets for industrial heating, biomass pellets for residential heating, and biomass pellets for the production of electricity, among other applications.
Properties and Sizes of Biomass Pellets
Pellet fuel or biomass pellets typically exhibit the following properties:
- They are mostly cylindrical in shape with a diameter ranging from 0.6 to 1.2 cm and a length of about 1 to 3 cm.
- Biomass pellets have a very high density, typically around 650-700 kg/m3.
- They possess a high calorific value, ranging from approximately 3,800 to 4,300 kcal/kg.
- Biomass pellets have a moisture content of less than 10 percent.
- The ash content in biomass pellets is usually kept below 3 percent.
- Additionally, biomass pellets have low sulfur content.
Composition of Biomass
The composition of fuel pellets or biomass pellets is divided into three parts:
- Combustible part: It can be further divided into two parts: volatile and carbon.
- Incombustible part (ash): Generated after the biomass has been completely burned. Each type of biomass has a different proportion of ash content.
- Humidity: Caused by the amount of water accumulated in the biomass.
Production Process of Biomass Pellets
The production process of fuel pellets or biomass pellets involves several stages:
- Raw material preparation: The raw materials are prepared by resizing them appropriately through coarse or fine chopping.
- Dehumidification: The moisture content of the raw materials is reduced to a suitable level for the compression process, typically around 10%, but not exceeding 20%.
- Fine grinding: The dehumidified raw materials are finely ground to remove stones or metals that may contaminate them and cause damage to the equipment.
- Mixing: Two or more raw materials are mixed together for pellet production.
- Compression: The raw materials are shaped into pellets of the desired diameter.
- Cooling: The biomass fuel pellets are cooled to solidify and stabilize them, ensuring their durability.
- Sizing and packing: The pellets are screened for quality assurance, and those that meet the standards are packaged accordingly.
Utilization of Biomass Pellets
Biomass pellets can be utilized in various forms, including thermal energy for residential use, steam production, and fuel for electricity generation in industrial boiler systems. By replacing fossil fuels, pellet fuel contributes to reducing energy costs while offering a higher calorific value. This transition also diminishes reliance on foreign energy sources and helps protect the environment by lowering carbon dioxide (CO2) emissions, thereby mitigating global warming.
Biomass Pellets and Thailand at Present
While biomass pellets have been used for heating energy and in various industries in foreign countries for many decades, their popularity has only recently increased in Thailand. The country's entrepreneurs are increasingly investing in this field due to the abundance of biomass resources available after harvest, such as rice husk, rice straw, sugar cane leaves, cassava rhizomes, corn cobs, palm bunches, coconut bunches, coconut husks, coconut shells, and rubber wood chips. However, the production sector faces limitations in terms of machinery, which often needs to be imported. Some entrepreneurs who modify or manufacture their own machines face technological limitations that require knowledge acquisition from abroad.
Nevertheless, it is expected that the fuel pellet manufacturing business, or biomass pellets in general, will continue to grow, supported by domestic biomass consumption promotion policies aimed at reducing coal consumption and increasing renewable energy utilization by the Ministry of Energy.