There is a widely held opinion that
wood pellets are just bits of wood and all are of similar quality. I was of a
similar opinion until I got involved with the biomass industry.

The first occasion I realised that
this was not the case was when a mushroom grower with a steam boiler that I
supplied changed pellet supplier and he found that a fill of his silo lasted 5
weeks instead of 3.5 previously. Another customer asked me if he should leave
the sand in the boiler. I thought he was joking but when I checked I found the
inside of the boiler was like the Sahara.

I brought an engineer from China to
inspect the boilers I had supplied. The first thing he did was to look at the
ash and in broken English it was “good pellets” or “bad pellets”. I realised
that there was a connection between the Chinese expert’s opinion on the fuel
and the problems I had with the boilers.

Most pellets sold here will claim to
have EN plus A1 certification. This covers a range of parameters: the most
important being %MOISTURE, %ASH, CALORIFIC VALUE AND MELTING POINT OF THE ASH.
I was not involved in the supply of pellets at this time so I had analysis
carried out on pellets from two suppliers to determine why usage could be
almost halved when supplier was changed. The big surprise was that the analysis
from both samples were similar. The ash melting point was not measured and I
later discovered that this was the critical factor. When the melting point is
too low you will get clinker which gives inefficient burning and damages
boilers.

The most important thing about the
cost of pellets is not the price per tonne, but price plus the heat obtained
from the pellets. See article in this issue about Premium Pellets Ltd.