Comparison of Wood pellet standards

Comparison of ISO, IWPB and PFI pellet standards

Mr. Staffan Melin has kindly compiled this piece of information to compare THREE major wood pellet standards ISO, IWPB (I1, I2, I3) and PFI Pellet Standards A. This information should serve as a baseline for any wood pellet-related designs as it is widely referred to in the wood pellet markets.

For ISO and IWPB, Net calorific value (NCV) is expressed in constant pressure and in as-received (a.r.) basis. The range is 16.0 to 16.5 GJ/tonne.
For American PFI, however, the calorific value is expressed in gross calorific value at constant volume, and provided NO weight basis to adhere to.

For the wood pellets that I have received from Pinnacle Renewable Energy Group, they have NCV of ~18 GJ/tonne, a lot better than the standard. Their wood pellets are made from mainly pine wood residues.
I'm thinking the lower NCV standard is meant to suit a wider range of biomass pellets made from non-wood materials, such as agricultural residues and municipal waste. These non-wood materials have lower reported NCV of around 14-17 GJ/tonne.

For PFI standard, the heating value is not given because according to the standard,
there are no specific grade requirements for heating value, however densified fuel manufacturers must provide a minimum higher heating value guarantee on quality marked product when these standard specifications are used in conjunction with the PFI standards.

Note on unit conversion:
1 GJ/tonne = 1 MJ/kg
1 GJ/tonne = 2326 BTU/lb
1 GJ/tonne = 4168.6 cal/g

References:

1. ISO/DIS 17225-2: Solid biofuels -- Fuel specifications and classes -- Part 2: Graded wood pellets
2. IWPB Industrial pellets specifications - Final
3. Pellet Fuels Institute Standard Specification for Residential/Commercial Densified Fuel, 2011