Almond shell vs. Wood pellet

Since many years, there were tries to value a subproduct of almond industry, which constitutes 75% of total almond biomass volume. Crashed and filtered almond shells, that we talk in this post about, surprisingly have similar characteristics to wood pellets. However, the biggest advantage of this energy carrier is undoubtedly its price, which is much more attractive, than its derived from wood competitor. 

When people think of almond uses they tend to just think of using the almond meat, which is often used in cosmetics and food industry. However, quite surprisingly, almonds have multiple by-products in fact.

Recently, many companies have installed plants to recover almond shells. Almond shell is the hard layer between the hull and the almond meat. The shell is what protects the almond from insects while on the tree. After the shell is removed from the meat at the huller, it is also used.

How to create bigger value of almond shells?

Almond shells can be ground up and used as bedding for garden planters and landscape material similar to wood chips. Nevertheless, almond shells are most commonly sold to co-generation plants to be used as a fuel source. In order to add more value to this by-product, many companies decided to perform tests, where they were trying to pelletize almond shells. Unfortunatelly, tests appeared not satisfactory, i.e. the energy costs during pelletizing process were too high to make the operation profitable.

Photo Credit : Isaac Sanz

After these tests, the conclusion was that in order to compete with pellets made of wood, almond shells has to go through improved proces of grinding, screening to obtain better quality of combustible material, without transforming it into pellet. Such improved quality almonds shell may be used in automatic stoves and biomass boilers.

The most important in the whole process is the facility, where improved quality almond shells can be produced. Such improved facility can achieved the efficiency of 5000 kg of clean and upgraded almond shells per hour.

The final size is obtained depending on the hardness of the shell – which depends on the variety of almond – and the needs of the client. The production period extends from November to March, coinciding with the harvest of the fruit.

The screened shell is usually packaged in paper sacks with manual sewing, although it can also be served in bulk, both in bigbag and in a feed bin with auger. The fines derived from the grinding constitute about 25% and are also marketed as fuel for industrial boilers.

How much costs it?

According to some data, 90% is still destined, unclassified, to large boilers, but in the sector is intended to increasingly derive small peel and screened domestic market, where the economic margin is greater.

From the almond processing sector it is ensured that the price of the cleaned and classified shell can be between 20 and 30 € lower per ton than the pellet. The untreated shell is priced at about  70 €/ t at the factory.

It is also noted that distributing at distances greater than 250 km triggers transport costs and the product loses competitiveness.

Users who prefer to buy treated peel include not only private individuals for their household equipment, but small businesses such as rural houses or industries that value using a dust-free biofuel.

Almond shell vs Wood pellet

According to the analyzes carried out by the BIOMASUD program for the certification of Mediterranean biomass, the almond shell presents a good quality from the physical, chemical and energetic point of view.

Almond shell has a similar pellet (17.5 MJ / kg of pellet vs 16.2 MJ / kg), lower specific gravity (692 kg / m3 of pellet compared to 379 kg / m3 of almond shell) and an air humidity of 6 to 9%, so it does not require drying. It has a low ash initial formation point compared to wood (1300 ° C versus 850 ° C for the shell) and an average ash content observed in BIOMASUD tests of 1.1%.

In addition to the price, one of the advantages of the almond husk is the less variability in its composition in different batches, suppliers or years, which results in less need for regulation of boilers and stoves.

Source: Calidad de biomasas mediterráneas. Nuevo sello de calidad para uso doméstico” BIOMASUD

Main Photo Credit: Isaac Sanz

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