Hearthstone Quality Home Heating Products, Inc.
Heritage Model 8090 Pellet Stove
Page 47 of 53
Appendix A – Residential Pellet Fuel
(Excerpt from
“Pellet Hearth Systems Reference Manual Second Addition” December 2008
)
In much of the world, the concept of home is linked
directly to the ability to maintain a heated
environment in winter months. With the energy crisis
of the 1970’s came the first notice that the source of
that heat and comfort had to be scrutinized. The
realization of limitations and eventual shortages for
finite, irreplaceable, fossil fuels spurred a new
interest in renewable, and therefore sustainable,
alternative fuel sources.
Almost simultaneously, the issue of waste surfaced.
The habits of our throwaway society not only
resulted in costly waste of valuable energy
resources, but also in a crisis in disposal space and
methods. The development of residential pellet fuel
responds to both the call for renewable biomass
sources of home heating fuels and waste stream
reduction.
1. PELLET PRODUCTION
As forest products companies produce lumber, plywood, and other goods, they create wood and bark residues
that contain energy. In the form of sawdust, bark, and chips, these residues are bulky and vary greatly in
moisture content. The process of pelletizing reduces their bulk by compression and increases their combustion
manageability by controlling consistency. Originally produced for industrial and institutional use, pellets entered
the residential fuel market with the introduction of the first home pellet appliances in the mid-1980’s.
1.1 RAW MATERIALS
Although a wide variety of materials, including sawdust and wood scraps from hard and soft woods,
shells and nut hulls, agricultural by-products, paper, and cardboard, is pelletized for use as fuel,
residential pellets are primarily wood-based residues. Corn, because of its natural similarity to pellets, is
used in some specially designed residential appliances. Because corn combustion differs from wood
pellet combustion, corn should not be burned alone or mixed with wood pellets unless the appliance is
specifically designed for corn combustion.
Because ash content and other factors presently limit or prevent the practical use of other agricultural
and paper products in most residential appliances. Increasing competition for forest industry by-products
and reduction in logging in some areas are a growing concern of pellet manufacturers. Pellet appliance
design, however, is responding to fuel manufacturers’ predictions of future shortages of premium grade
fuel with research and development aimed at greater ash tolerance.
The amount of residues available from processing logs varies depending on factors such as log size,
timber species, lumber dimensions, moisture content, and processing machinery. Typically, 5 to 10% of
the original material is available for pellet fuel conversion. The raw materials may be received at the
pellet processing plant as residues from kiln dried lumber or as residues from freshly processed (green)
wood in which the weight of moisture may exceed the dry material weight. Heating, or caloric, value of
finished pellets ranges from 7,000 to over 9,000 Btu (British thermal units) per pound (at 5% moisture),
with resinous species (such as pines and fir) having slightly higher gross caloric values than non-
resinous species (hardwoods) and bark. Average Btu content of pellets as received by the consumer is
8,300 Btu per pound at 5% moisture.
