What Is a Biomass Boiler?
A biomass boiler is a heat source device that produces steam and hot water by using industrial waste such as wood chips, paper waste, and scrap tires as fuel instead of fossil fuels such as heavy oil, which were conventionally used to produce steam and hot water.
One of the main features of biomass boilers is they can significantly reduce emissions of carbon dioxide, a greenhouse gas, compared to burning fossil fuels.
By burning biomass at temperatures above 800 degrees Celsius, these boilers are extremely environmentally friendly, reducing the generation of dioxin, a pollutant.
Uses of Biomass Boilers
Biomass boilers are used in a variety of applications, the most common being small-scale power generation systems.
They produce approximately 4 tons of steam per hour, which drives a power turbine that can generate 300 kilowatts of electricity.
In addition to steam, the system also produces hot water, which is used to heat and warm agricultural facilities and to supply hot water to thermal baths.
Biomass boilers are also used in large-scale chemical plants that require large amounts of steam, hot water, and hot water, and as drying equipment in various factories.
Principle of Biomass Boilers
There are three main types of combustion methods for biomass boilers: direct combustion, pyrolysis gasification, and biochemical gas.
In the direct combustion method, biomass fuel is directly combusted to generate steam and hot water. The steam generated by the combustion process turns a turbine to generate electricity.
The pyrolysis gasification method uses the same fuels as the direct combustion method (wood chips, thinned wood, combustible garbage, etc.), but combustible gas is generated by heating, and steam and hot water are generated by burning the gas.
The biochemical gas method uses livestock manure, raw garbage, or sewage sludge as fuel.
Instead of burning these fuels, they are fermented to produce a gas called methane, which is then used to turn a gas turbine to generate electricity.
Although it is tempting to think that both methods contribute to an increase in so-called greenhouse gases, they are based on the idea of being “carbon neutral”. This is because they efficiently obtain energy directly from within the biosphere, rather than from fossil fuels, thus closing the carbon cycle and not leading to an increase in carbon dioxide emissions. This is based on the idea of “carbon neutrality”, which does not lead to an increase in CO2.
Points to Keep in Mind When Introducing Wood Biomass Boilers
- Fuel Costs
Wood biomass boilers are said to have lower fuel costs than fossil fuel boilers. Fuel can be procured from forestry, manufacturing (wood processing), construction (mainly general house construction), and industrial waste disposal industries. To maintain the low fuel cost, a cooperative effort from many sectors of the public and private sectors is necessary to seek a stable supply of both mass and fuel.
- Equipment Costs
Compared to fossil fuels, wood biomass boilers have a smaller calorific value of wood fuel and vary in quality. This means the equipment cost will be higher to obtain the same output. To popularize the use of these boilers in the future, it is desirable to expand subsidies from the government as well as technological improvements.
- Disposal of Combustion Ash
In the case of wood fuel, combustion ash is generated at around 10% of the fuel input. Although it is reasonable to return the ash to the soil since it is of ecological origin, it is also a sensitive issue since, under some laws, it is considered waste from industrial activities. The decision is left to each municipality, and in practice, different municipalities make different decisions.
Fuel for Wood Biomass Boilers
The fuels for wood biomass boilers include firewood, wood chips, and wood pellets.
Firewood is wood that has been cut from logs into manageable sizes and dried to increase combustion efficiency. Wood chips are shredded wood offcuts from the forestry, manufacturing, and construction industries, and are easier to transport than firewood. Wood pellets are made from wood chips, sawdust, etc., which are formed into small pieces and processed for easy combustion. The price varies depending on the number of man-hours involved in the processing. The design of the equipment is determined by the fuel to be procured and the amount of steam and heat to be generated.
Potential of Wood Biomass Boilers
Woody biomass boilers, like wind and solar power generation, are classified as a renewable energy source. Compared to other renewable energies, wood biomass boilers have the advantage that they are not affected by weather conditions. If fuel procurement and other issues can be resolved, it will be a very promising energy source.