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Good time to consider converting your crop straws into pellets… on your own

23/02/2017

It is not as complicated as you might initially think

stalk_picMost of us are familiar with this piece of advice, ‘If it ain’t broken, don’t fix it.’  The uses of crop straw are endless: natural fertilizers, fodder and bedding for livestock, basket weaving and home insulation, the list goes on and on.  Crop straw are excellent raw material for producing heat and/or electricity.  So, what exactly can farm owners benefit from by converting these straw into pellets, and what is the estimated initial capital outlay?

 

For a start, consider the following facts of using straw pellets for fuel:

 

  1. Straw pellets contain a higher calorific value than crop straws, which produce more heat and energy per unit:
     
    S/no Biomass Approx. calorific value (MJ/Kg)
    1 Canola 16.3
    2 Wheat 18.0
    3 Rice 18.0
    4 Corn 16.0
    5 Soybean 22.0
    6 Cotton 15.5
    7 Sugarcane 18.0
  2. Natural crop straw have product energy density of around 140kg/m3 in bale form.  In pellet form, the energy density can increase to as much as 650kg/m3
  3. Straw pellets possess qualities such as: low moisture content, high energy, homogeneous size and shape, which contribute to the consistent heat and/or electricity
  4. Straw pellets are clean and an environmentally friendly alternative to oil and gas.  Burning them emits almost zero CO2 emission because during the plant growth stage, it absorbs almost the same amount of CO2 as it produces during burning
  5. Producing straw pellets can be a cheaper option for generating heat since farm owners can obtain crop residue as raw materials for almost free
  6. Easy storage for long period – Using sealed bags, the pellets can be easily transported and/or stored for long periods of time
  7. Ash content is 5% or less, and the residual ash after burning can be used as mineral fertilizer

Using straw pellets for animal bedding have several advantages over natural straw:

  1. Easier and more economical to transport (better weight/volume ratio)
  2. Easy to store and use (pour out from bucket like sand)
  3. Easy to maintain and clean

The usage of straw pellets as fuel has been around for a while, as commercial factories across the world have been producing them in large quantities and selling them to be used for both residential and commercial purposes.  So what about farm owners that are left with a large amount of crop residue (e.g. straw) after harvesting? It’s equally possible for them to convert these to pellets right in their own homes, only requiring two machines for a start – a hammer mill to pulverize crop straw, and a compact pellet mill to compress them into pellets.  The estimated initial capital outlay, for starters, is around USD1500.00* but the actual figure will depend on output expectation.  The process includes three main steps:

  1. Drying of crop straws – It’s not necessary to convert them into bales.  Drying them under the sun is an almost free option.  Ensure that the straws achieve 15% or less moisture content first
  2. Pulverizing the crop straws – Load the dried crop straws into the hammer mill.  Ensure that no foreign particles such as stones, rocks or metallic particles
  3. Pelleting the pulverized straws – Load them into a compact pellet mill and collect the hot pellets in a basket.  Leave it to cool before storing them in sealed bags

(Note: * – this excludes shipping and port custom charges)