Biomass boilers and pellet stoves; examples and types - Green Ecologist

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Biomass boilers and the use of pellet stoves

If there is something that is booming today, it is none other than the issue of renewable energy and its "derivations" transposed to the world of energy sources. biomass boilers or the always effective pellet stoves. And, despite the fact that there are still many people who are reluctant to do so, the use of fossil fuels does nothing but lead us to a truly disastrous scenario.

There are many studies, even from prestigious universities worldwide, that emphasize the fact of using renewable energies to be able to have a much more sustainable lifestyle and more in line with the environment.

However, from the official levels, even from some of the most important governments in the world, they are still reluctant to this type of investment and continue to have their fundamental base in fossil fuels.

However, and especially in some very specific geographical areas, such as small towns and small rural areas, at least within the Spanish geography, what we know as biomass boiler.

Heating systems that, in essence, use fuels from the land itself such as olive stones, almond or hazelnut shells, wood chips, briquettes, firewood or pellets.

Remember that we have an excellent article on insulating materials from here that can complement this information of interest.

I want to leave a small video to clarify concepts and what is the main function:

Types of biomass boilers

Yes we have to talk about the main types of biomass boilers, we have to talk about two fundamentally. We have, on the one hand, those boilers that are considered as polyfuel systems and those boilers or stoves that only use a single fuel. Although we really should, the most correct designation would be based on the types of biomass used for air conditioning.

Within the multi-fuel boilers, we can use those that we have already mentioned just a few moments ago, which are none other than the pellet, the olive stone or even the almond shell. Its system allows it not only to admit the different types of fuel but at the same time it also allows them to make the most of their calorific power.

On the other hand, we have a type of single-fuel boiler which is usually a little smaller and at the same time has a little lower performance. These types of home heaters, which rather have the appearance of small stoves, we can only administer one type of fuel from among those we have already discussed.

Thermal applications with production of heat and domestic hot water are the most common in this sectorAlthough it can be used, it can be used in areas such as electricity production. You can also feed a good air conditioning system (hot and cold) in the same way as if it were done with diesel, gas or electricity. (See also heat recovery units or the concept of solar cooling)

According to thermal production it can be classified

  • Stoves, normally wood or pellet, whose main function is to heat a single room and normally act simultaneously as decorative elements that we can even see on some floors.
  • Low power boilers intended for single-family homes or small and reduced-size buildings. (Of interest heating with aerothermal)
  • Boilers designed for a residential building or block, which act as heating
    centralized and that shows complexity in its facilities.
  • And the so-called thermal power plants that heat several buildings or facilities (The District Heating) or group of houses.

Annual costs and maintenance

Due to the development of the sector in recent years and new technologies, the useful life of the biomass boiler and the performance of this type of facility is already high. The annual costs compared to other types of fuels are:

The average investment period for a 140 m2 single-family home in a cold area, for a DHW installation and underfloor heating (Boiler Thermal Power = 15 KW and with an energy demand of 22,401 Kwh / Year)

Pellet stoves

Lately there is a lot of talk about the advantages of pellet stoves and how well the biomass in stoves For the day to day. But it must be recognized that there is a great variety within the world of chimneys pellet with many functions.

First we will see what is the most efficient heating system, which are undoubtedly the boilers and pellet stoves with a long use:

It should be remembered that the regulations of international application is ISO 17225-2, where we have several certification seals such as Biomasud or Nplus-A1 (In the portal they have a Calculation Tool for CO2 emissions and to calculate the necessary power), which identifies that the manufactured one is with wood from without chemical treatment, with low nitrogen and / or chlorine content, and ash.

Ultimately, this regulation ensures that the quality of the supplied pellets has followed manufacturing and quality standards. Let us remember that although there are different types of pellets, is he more efficient biofuel.

Pellet heating

As we have already seen in the previous graph, within all systems for heating the home in winter, the pellet heating is really excellent with a heat efficiency almost outstanding.

As a basis for the characteristics and recommendations we can highlight …

It is advisable to require the pellet supplier to indicate exactly the origin and type of biomass from which they are composed to avoid misunderstandings with others types of pellets not suitable for biomass boilers and chimneys.

The use of natural wood pellets for being the most suitable for use in the air conditioning of homes and large buildings.

Tips like quality reflection ofa good pellet It must be shiny in appearance, it must not have dust around it, with a uniform color tone and its structure must be more or less compact, it must not have cracks or deep cuts on its surface.

The pellet must be denser than water, so if we want to check so we only have to submerge it in a bucket with water and check to see if it sinks, but taking into account that if we observe that after five minutes still submerged in the bottom and compact, it means that it possibly contains additives that will cause combustion with excess smoke.

Types of Pellets

In the following table we can see the properties of thetype of pellet according to its quality. Obviously their quality is related to the sale price that we can find in stores:

The characteristics of the pellets compared to other fuels within the same range:

How a pellet stove works

Knowledge how pellet stoves work It can be a bit complicated, so a good image can give us a good idea. The Italian manufacturer Piazzetta has an infographic worthy of your viewing:

Since we have seen how this works biomass stove, now we are going to see the classification …

Types of pellet stoves

  • Hot air stove. Several tubes that channel the hot air through the rooms of the house or in the room itself. Is a pellet heating well known and installed in many homes.
  • What they call thermo stove (Hidroestufas), where the water is heated to heat the home through a circuit of radiators (There is also the possibility that they have an accumulator)
  • The recessed ones in the wall that we have all seen in an apartment or house, and are more typical of firewood, although they can also be used and even combined with pellets.
  • Or large boilers that we can use in more open spaces or with more “industrialized” needs, so to speak.

Regarding the pellet stoves price there is a great range; from new ones for more affordable housing, to industrial ones with more expensive prices.

We must remember that there is a large second-hand market where we will find them cheaper and we can always take advantage of a good opportunity without wasting quality.

The best brands in biomass boilers they suppose a higher economic outlay but without a doubt we are buying a heating system we want it to last for years, so the cheap pellet stove It is not a good investment according to the opinions of the experts.

Advantages of these heating systems

Talk about advantages of heating systems that work from biomass, is to list a series of advantages that in many cases is not known. Therefore, we believe that it is a good idea to talk about the main aspects that make these boilers highly recommended from our point of view…. What are really the advantages or disadvantages of using a biomass boiler?

  • First and foremost, we have sustainability. And, we have to take into account that the fuel they use is completely renewable year after year. In addition, it must be mentioned that it is a much cheaper fuel than for example diesel or gas, and therefore the maintenance of this heating system is much cheaper.
  • They have high efficiency and effectiveness. They have constant calorific value and it is always available. We can improve them with thermostat control for heating, increasing their efficiency and reducing costs.
  • We have to talk about the security of these systems. It is true that there was a time, especially when the biomass boilers, in which his safety was doubted. Well, we must emphasize the fact that today, and especially large multi-fuel boilers, have complete and complex safety systems from which we will not have to worry about anything at all. In fact, it could be said without fear of being wrong, that within safety, this type of boiler is at the same level as diesel or gas boilers.
  • A final advantage is that the suppliers of this type of fuel can be counted in the hundreds today. Contrary to what people may think at least at first, it is not difficult to acquire almond shell, olive stone or pellet. What's more, due to the great competition that exists especially within rural areas, we can assure that the price of this is really low.


Solve the question of what disadvantages do pellet stoves provide us or the different heat converters It is complex since in many cases it requires, depending on the characteristics and particularities of the location, the possible use or the space to be heated, among other elements involved, but broadly speaking:

  • Normally, performance of biomass boilers they are somewhat inferior to those of the hips that use a liquid or gaseous fossil oxidizer although the technology in this field is advancing by giant steps. It is necessary to consider that the price in the buy if it will influence in a better or worse performance.
  • For misfortune, he biomass heater It has a lower energy density, which causes the need for superior spaces and storage systems.
  • Given the types of fuels used, the feeding and subsequent removal of ashes are more complex, thus requiring higher maintenance and operating costs. In addition, the routes of distribution of the materials for combustion are not as developed as in other fossil fuels, so sometimes access to them is not easy.
  • Many of these resources have high moisture contents, which means that in certain applications a previous drying process may be necessary.

Depending on the fuel we use, we will have broad advantages and disadvantages. We leave the following chart for a better understanding:

Prices of this type of boilers

In terms of costs, as expected, we would have to analyze exactly what kind of boiler do we need. Multi-fuel boilers can have very high performance and therefore their price can even amount to € 3,000. Anyway we have to take into account that they have self-administration systems, a panel in which we will be able to regulate the temperature in a very simple way as well as extraordinarily precise security mechanisms.

Even so, if what we want is a slightly cheaper biomass boiler, we can resort to monofuels. It is true that they are somewhat less secure systems, that they have a slightly less attractive visual aspect and on which we will have to pay much more attention. Anyway, we can find mono-fuel heating system that can be around € 500 perfectly.

The costs according to the type of fuel for thermal uses that we will use vary. From the following table with prices for this year we can have a general idea for Spain:

As a note we leave the technical guide for thermal biomass installations in buildings (HERE) that we find very interesting or more manuals and guides from HERE.

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