In our previous post, we discussed biomass energy . We explored everything from what it is, how it works, and where it comes from, to the advantages and disadvantages of this energy source. We briefly mentioned biomass boilers, but didn't go into detail, intending to cover them more thoroughly in this article.
In this post, we will delve not only into the different types of biomass boilers , but also into the controversy surrounding the CO2 balance that arises when analyzing biomass as a clean energy source.
What are biomass boilers?
Biomass boilers are devices that utilize the energy contained in biomass to generate heat for heating and hot water in homes and buildings. They operate by burning natural materials such as wood pellets, olive pits, forestry waste, and nut shells, among others.
The operating principle of a biomass boiler is not significantly different from that of traditional boilers. In them, biomass fuel is burned , generating a flame that heats a water circuit. This hot water is then distributed through the heating system or used for domestic hot water. To maximize efficiency, it is recommended to install a storage tank to store the heat produced, extending its use over time, similar to solar energy systems.
In addition, biomass boilers require a container or silo where the fuel is stored. From there, it is transported to the burner either by an auger or a suction system . After combustion, the resulting ash accumulates in an ash pan, which must be cleaned several times a year to prevent it from becoming saturated.
Types of biomass boilers
When purchasing a biomass boiler, it's important to understand the type of fuel it can use and its storage requirements. Different types of biomass boilers exist , depending on the fuel they use and their intended application.
Some boilers allow the use of different fuels, while others, such as pellet boilers, only accept one type of fuel . The former are more suitable for industrial installations, since they handle larger quantities of fuel and have a greater storage capacity.
On the other hand, pellet boilers are more common in the residential sector and have adequate power for medium-sized homes , providing heating and domestic hot water for areas up to 500 m².
Depending on the type of biomass and its moisture content, these boilers can have varying efficiencies. Some achieve efficiencies close to 105% , which translates to fuel savings of up to 12%. Fuel moisture is a key factor, as it directly influences boiler performance.
- Dry fuel boilers: They have a low thermal inertia and maintain an intense flame that reaches very high temperatures, even capable of crystallizing the resulting slag.
- Boilers for wet fuels: Their design allows burning fuels with a higher moisture content thanks to a high thermal inertia. These boilers are designed to dry the fuel before its gasification and complete oxidation, avoiding the formation of black smoke.
Pellet boilers-olive pits
Among the boilers that use pellets as fuel, we find several types designed for different uses and powers.
Modular pellet biomass boiler
These models are designed for installations with power outputs ranging from 91 kW to 132 kW , primarily using pine pellets as fuel. They are designed to operate in cascade and allow for highly efficient fuel use thanks to suction systems and reserve hoppers.
One of the most outstanding features of this boiler is that it reduces fuel consumption by lowering the temperature of the combustion gases, achieving efficiencies of up to 95%. Furthermore, it is equipped with an automatic cleaning system for both the burner and the ash pan, minimizing the need for manual intervention.
Wood boilers
Biomass boilers can also use logs as fuel . These types of boilers are widely used in rural areas or in homes with easy access to firewood.
High efficiency gasification boiler
This type of boiler is based on reverse flame gasification technology. They are available in 20, 30, and 40 kW versions , and their main advantage is that they achieve an energy efficiency of 92%, far exceeding the 80% required by current regulations.
The advantages of this type of boilers include:
- High energy efficiency with optimal use of fuel.
- Charging autonomy up to seven hours, reducing the frequency of loading firewood.
- Electronic modulation which automatically adjusts the generated power according to demand.
- Incorporation of a overheating safety system, ensuring reliable and safe use.
Advantages of biomass boilers
Among the main advantages of installing a biomass boiler is the low price of biomass compared to fossil fuels . Since it is not tied to international markets, its price is more stable and competitive. Furthermore, biomass resources are usually local, which reduces transportation costs.
Another of its greatest advantages is that biomass technology is safe and efficient . Current biomass boilers, particularly those that use pellets, have an efficiency close to 90%, making this option a cost-effective and renewable alternative.
Finally, it's worth noting that biomass boilers use a clean and virtually inexhaustible energy source . Although they emit carbon dioxide (CO2) during operation, this is neutralized because the biomass previously absorbed that same amount of CO2 during its growth. Furthermore, the use of biomass contributes to forest management, helping to prevent wildfires.
Disadvantages of biomass boilers
However, biomass boilers are not perfect. They have a lower calorific value compared to other fossil fuels . For example, pellets have approximately half the calorific value of heating oil, which means that more fuel is needed to generate an equivalent amount of energy.
Furthermore, biomass storage, such as pellets, typically requires large storage spaces . This includes having a nearby pellet silo where the fuel can be stored for extended periods.
The controversy over the CO2 balance in biomass energy
One of the most debated issues surrounding biomass energy is its CO2 balance . Because burning biomass involves releasing carbon dioxide into the atmosphere, the question arises as to whether this process is truly better for the environment compared to fossil fuels.
The answer lies in the fact that, as plants, trees, and other vegetation grow, they absorb CO2 from the atmosphere through photosynthesis. This same amount of CO2 is released when the biomass is burned, resulting in a carbon-neutral balance; that is, it does not contribute to the increase of CO2 in the atmosphere or to the greenhouse effect, as fossil fuels do.
Although there are critical viewpoints that claim this balance is not so perfect, the truth is that, unlike what happens with fossil fuels, the CO2 released by biomass belongs to the current biological cycle, while the carbon in fossil fuels was captured and stored for millions of years underground.
Furthermore, it is important to note that biomass can help reduce transport-related emissions, as it is a local resource that avoids the need for long fuel journeys, which also has a positive impact on the environmental balance.
Studying all this in depth, we can say that biomass is a renewable energy source that, although not so well known, can have a great impact on reducing the use of fossil fuels and preserving the environment.