Biomass energy is a type of renewable energy obtained by burning organic compounds from natural processes. These are organic residues such as trimmings, olive pips, nut shells, wood residues, etc. etc. These are from nature. You could say it is a waste product of nature.
These organic residues are burned by direct combustion or can be converted into another fuel such as alcohol, methanol or oil, and in this way we get energy. We can also get biogas from organic waste.
Different sources of bioenergy generation
The main characteristic of bioenergy is that it is a type of renewable energy and therefore sustainable for society and its energy consumption. As I mentioned earlier, this energy is obtained by burning various types of waste, forest or agricultural, which otherwise would not be used at all. However, we are going to see what types of biomass sources are used to produce bioenergy and what they are used for:
Bioenergy can be obtained through energy crops that are designed exclusively for this purpose. These are some plant species which have hitherto had little or no nutritional or human function, but which are good biomass producers. This is why we use this type of plant for bioenergy production.
Bioenergy can also be obtained through various forestry operations, where forest residues cannot be used or sold for other purposes. Cleaning these forest residues has the advantage that, in addition to helping to clean up the area and generate sustainable energy, it avoids possible fires due to burning residues.
Agricultural residues for biomass
Another source of waste for bioenergy production can be the use of residues from industrial processes. This can be from joinery workshops or factories that use wood as a raw material. It can also come from disposable waste such as olive pips or almond shells.
How is biomass energy produced?
The energy obtained from organic residues is produced by burning them. This combustion takes place in boilers where the material gradually burns off. This procedure produces ash, which can then be used as compost. An accumulator can also be installed to store excess heat and use that energy later.
With organic waste it is possible to use fuels such as:
Biofuels:
They are obtained from organic residues of both animals and plants. By their nature, these residues are renewable, i.e. they are continuously produced in the environment and are not depleted. The use of biofuels makes it possible to replace fossil fuels produced from oil. Agricultural crops, such as maize and cassava, or oil plants, such as soybeans, sunflowers or palm trees, can be used to produce biofuels. Forest species such as eucalyptus and pine trees can also be used. The environmental advantage of using biofuels is that they are a closed carbon cycle. That is, the carbon that is released when biofuels are burned has already been previously absorbed by plants during their growth and production. Although this is currently under debate, as the balance of absorbed and emitted CO2 is unbalanced.
Biodiesel:
This is an alternative liquid biofuel that is produced from renewable and domestic resources such as vegetable oil or animal fats. It is petroleum-free, biodegradable and non-toxic as it contains no sulphur or carcinogenic compounds.
Bioethanol: This fuel is produced by fermentation and distillation of starch contained in biomass, which is first extracted using enzymatic processes. It is obtained from the following raw materials: starches and cereals (wheat, corn, rye, cassava, potatoes, rice) and sugars (cane syrup, beet syrup, sugar syrup, fructose, whey).
Biogas:
This gas is a product of the anaerobic decomposition of organic matter. In landfill sites, biogas is recovered through a pipeline for further energy use.
What is biomass used for and what is its consumption in our area?
In general and more or less similar to geothermal energy, biomass is used to generate heat. On an industrial level, we can find the use of said heat for power generation, although this is more complex and expensive. To use the heat generated by the combustion of organic residues, biomass boilers are installed in homes for heating as well as for water heating.
Biomass boilers and their operation
Biomass boilers are used as a source of biomass energy and for generating heat in homes and buildings. They use natural fuels such as wood pellets, olive seeds, forest residues, nutshells, etc. They are also used to heat water in houses and buildings.
The operation is similar to any other boiler. These boilers burn fuel and generate a horizontal flame that enters the water circuit of the heat exchanger, thereby producing hot water for the system. To optimise the use of the boiler and organic resources such as fuel, an accumulator can be installed that stores the heat produced, similar to the way solar panels do.
To store the organic waste to be used as fuel, the boilers need a storage container. From this container, using an endless auger or suction device, it is taken to the boiler where it is combusted. Combustion produces ash, which must be drained several times a year and stored in an ashtray.
Types of biomass boilers
When deciding which type of biomass boiler we are going to buy and use, we must analyse the storage system and the transport and handling system. Some boilers allow burning more than one type of fuel, whereas others (e.g. pellet boilers) allow burning only one type of fuel.
Boilers which allow combustion of more than one type of fuel have a larger storage capacity as they are larger in size and capacity. They are usually designed for industrial use.
On the other hand, we find it as pellet boilers, which are the most common for medium capacities and are used for heating and hot water with batteries in houses of up to 500 m2.
Benefits of using biomass energy
Among the benefits we find in the use of biomass as energy:
It is renewable energy. It is about using waste produced in nature to produce energy. This is why we have an inexhaustible source of energy, because nature is constantly producing these types of waste.
Reduces greenhouse gas emissions. As we mentioned earlier, the emissions we produce when we burn them were previously absorbed by crops during their growth and production. Today, this is controversial because the balance of emitted and absorbed CO2 is not balanced.
The price on the market is low. This use of energy contained in biomass is very economical compared to fossil fuels. It usually costs a third less.
Biomass is a rich resource worldwide. In almost every place on the planet, waste is generated in nature and can be used for its own purposes. In addition, there is usually no need for a large infrastructure to bring the waste to the point of combustion.
Disadvantages of using biomass energy
There are few disadvantages of using this energy, but they need to be considered:
It can be expensive in some areas due to the more difficult conditions of biomass extraction. This also tends to occur in use projects that involve the collection, processing and storage of some types of biomass.
Large areas are needed for the processes used to generate biomass energy, especially for storage, as residues tend to have a low density.
Sometimes the use of this energy can cause damage to ecosystems or fragmentation due to biomass harvesting activities and alteration of natural spaces for resource extraction.