1. Fuel - wood and its calorific value.
The heat locked up in a fuel is expressed
as its 'calorific value.' To measure the calorific value of wood
in a laboratory, you take a small sample and oven dry it until
all moisture has been driven off. Then you weigh it carefully
and place the sample in a device called a 'bomb calorimeter'
which enables you to burn the sample completely while measuring
the amount of heat produced. With wood, the number arrived at
is likely to be around 8,600 BThUs.
is all very academic and bears little relation to what goes on
when you throw a log on the fire! But the results are of interest
nevertheless in that they show show us that there is close
correspondence between the calorific values of all types of wood
fibre. In other words you can take sap wood or heart wood
from oak, spruce, beech, rhododendron, balsa, teak, pear tree
pretty well any wood you can lay your hands on
and they all turn out to match each other quite closely in terms
of calorific value.
- wood and peat are both famous for giving you "two heats"
the first when you harvest and render them ready for use
and the second when you burn them! Although different species
of tree may deliver equal calorific values, some will always
be much more cost-effective to process than others because they
are much easier to saw and split.