Learning Portal
On the Learning Portal, we have collected a lot of good-to-know information about the art of making your own pellets. After going through all sections below you will have a better understanding of which materials works best, what is good to keep in mind and how the actual pelletizing is working. Apart from this compact place of learning, we are at your disposal on e-mail and telephone to answer any question you may have about the craft. No matter if it is a question about which machine that will suit you the best, materials and so on.
Getting started
(Home made) pellets is either used for energy or feeding animals, among other uses. Unlike industrially made energy pellets, home made pellets can be made successfully from a wide range of materials. More about this under the tab "Raw materials".
First and foremost, you will need a good pellet mill. We offer a wide range of machines suitable for almost all thinkable kind of pelletizing purposes. product quiz to find a suitable machine that fits your needs.
Burning pellets, whether home-made or bought, is considered carbon neutral. The carbon dioxide released when burning pellets has at some point been captured by the organic material being burned. Home-made pellets are always more environmentally friendly as purchased pellets are transported long distances before they reach your stove/burner.
The fineness of the material before it is fed into the pelletiser is a factor that affects both pellet quality and production speed. A good guide is that the particles should not be larger than the matrix hole, which is usually 6 mm. It is certainly possible to put whole leaves into the pelletiser, but production takes longer. To quickly and easily create a good grain size on leaves, for example, is to run over the leaves with a lawnmower a few times and then rake them up.
When you start your machine for the first time, in addition to reading the manual carefully and adding the correct oil, prepare a batch of polishing compound. This is to polish the moving parts of the press. The recipe should be followed carefully and the batch should be run through the pellet machine again and again for about 30 minutes. More on this in the product manual.
Every eight hours of operation, the moving parts of the machine should be lubricated with a lubrication injector supplied with all our pellet presses.
Before you finish for the day, we recommend mixing oil into the raw material so that what sticks to the mould has a high fat content, this will prevent any rock-hard pellets from sticking and making production more difficult the next time you start the machine. The best thing to do is to have some cooking oil ready in a regular flower sprayer. Or do as they do in the factories, add some grain before you shut down the pellet press.
Materials
Leaves in their natural form are unsuitable for burning. Pelletised leaves, on the other hand, have proven to be more energy efficient than wood pellets, with the only drawback being that the material produces more ash when burned, which adds to the workload.
In the Netherlands, researchers at the Hanze University of Applied Sciences in Groningen have concluded that pellets made from European autumn leaves can largely replace wood pellets, as they are reported to have essentially the same properties as wood pellets.
The reason leaf pellets are not on the market today is simply that collection in the quantities required to make it profitable to produce leaf pellets commercially is not practical. However, for small-scale producers of their own pellets, leaves can be the most efficient and similar substitute to purchased wood pellets. In addition, it is a natural extension of the collection work that is done every autumn anyway.
Ashes: 1,4-9 %
Sulphur: 0,089 %
Calorific value kg: 4.98 kWh
Ash melting temp: 1230 °C
The most common form of pellets is made from sawdust and shavings. However, it is unusual for ordinary households to have large quantities of sawdust. For those who, for various reasons, have access to sawdust/cutterdust in large quantities, this is an excellent raw material for making fuel pellets.
Ashes: 0,4-1,7 %
Sulphur: 0,2-0,4 %
Calorific value kg: 4.8 kWh
Ash melting temp: 1200 °C
Straw is fine to pelletise but be careful what your equipment can burn. Straw contains a lot of ash, and the ash melting temperature is very low, which increases the risk of sintering and other problems with the burner. Preferably use a grain pan adapted for burning straw.
Ashes: 3-12 %
Sulphur: 0,01-0,2 %
Calorific value kg: 5.05 kWh
Ash melting temp: 930 °
Like sawdust, it is suitable for making pellets from wood materials. To process brushwood, twigs and branches, you need to be able to pulverise them into sawdust first. No pellet press can handle unprocessed wood. Neither domestic pelleting machines nor large industrial plants. The best option is to invest in a hammer mill.
Ashes: ∼1-3 %
Sulphur: ∼0.3-0.5 %
Calorific value kg: ∼4.3 kWh
Ash melting temp: ∼1200 °C
Back in 2005, Jerry Cherney, an agriculture professor at the prominent Cornell University in Ithaca, USA, presented a report on the profitability of producing energy from pelletised grass. The report found that grass pellets had 96% of the energy content of wood pellets in terms of BTU. Although Mr Cherney said that slightly higher ash production had been observed when grass was burnt, this was purely a matter of convenience to be set against the economic benefit.
For farms and ranches with larger supplies of hay and grass, production can be scaled up to exceed the annual heating needs of the entire property. It is important to note that some grasses that are not leached of minerals will produce nitrogen oxides and sulphur when burnt. Leaching also drastically reduces ash formation during combustion as the minerals dissolve in the water. Leaching is best done outdoors where you let the rain ”wash” the grass. The example below is for the grass variety Miscanthus.
Ashes: 4,7 %
Sulphur: 0,06 %
Calorific value kg: 5.1 kWh
Ash melting temp: 800-900 °C
Horse manure is arguably the most controversial material candidate for self-pellets. Horse manure is expensive to dispose of as a farm owner and is quite unpleasant to handle. The truth is, however, that horse manure is excellent for burning. However, burning requires authorisation from several authorities. Contact the Swedish Board of Agriculture for further information.
Ashes: Unknown
Sulphur: Unknown
Calorific value kg: Unknown
Ash melting temp: Unknown
Useful info
Most plant material in the garden contains lignin, It is nature's own glue and will be your best friend in the production of pellets. For the lignin to be released from the biomass, water vapour is required, which is one reason why the moisture content of the biomass to be pelletised is so important. A pelleting machine produces frictional heat, which in turn heats the material to release the all-important vapour from the moisture content of the material, dispersing the lignin deep into the pelletised biomass. This process makes the pellets hard and shiny, which helps them burn longer and more evenly. It also makes it more durable and does not crumble, making it easier to handle.
The moisture content of the base material is vital for releasing lignin in pellet production. When it is too low, the pellets will be crumbly or, at worst, just come out as powder. If it is too high, the pellets will be soft and floury, perhaps even gummy. Try to maintain a moisture content of 15% throughout the base material you are pelletising.
Burning moist fuels, whether acidic wood or moist pellets, is bad for the stove, bad for the environment and bad for health. Wet pellets generate more carbon monoxide, hydrocarbons and other by-products than dry pellets. In addition, moist pellets generate less energy in kWh, so always let your pellets dry before burning them. Below is a summary of what the same material (GROT) looks like at different moisture contents in the raw material.
A good indicator of what is profitable is what the consumption of energy yields in energy. With our smallest model, one hour of pelleting autumn leaves should produce 60-100 kg of pellets with an energy content of at least 4.9 kWh per kg. This means a production of pellets with an energy value of up to 490 kWh per hour. That's a pretty good deal, any way you slice it.
To calculate the operating cost of our electric pellet presses, you can first calculate the hourly electricity cost. This figure is divided by the hourly production rate. This is often a few tens of pennies per kilo of finished pellets.
Leaching is a process whereby biomass is washed clean of ash-forming minerals. One simple way is to leave the biomass outdoors to be exposed to rainfall for a few weeks. Ash formed during combustion consists largely of water-soluble salts which can be removed by the leaching process prior to pelletisation, this raises the ash melting temperature and reduces the amount of ash produced. An example of this is yellow straw that is left outdoors for leaching becomes grey in colour and has several percent lower ash content than the untreated yellow straw.
This process can be used for autumn leaves, grass, straw, hay and similar materials.
With a pellet basket, you can easily and safely burn your pellets in any wood-burning stove or tiled stove. Be sure to choose a pellet basket that is not too big for your stove.
Producers are responsible for all handling, safety, manufacturing and any licences (e.g. manure burning). You are also responsible for what you feed your stove or burner with.
We therefore never encourage our customers or other interested parties reading this to do anything but sell pelletising equipment and provide general information on making your own pellets.
