Wood-Chip Heating Systems - Biomass Energy Resource Center

Randolph Union High
School, Randolph,
Vermont
System Size: 3.5 MMBH
Manufacturer: Chiptec Wood
Energy Systems
The wood heating plant
shown heats a large
building encompassing
a middle school, a high
school and a vocational
center. The wood system
was installed when old
heating equipment was
modernized.
Public Policy
The economic and other reasons for burning
biomass are the basis of state and federal energy
policies that encourage the increased use of biomass
for energy in the Northeast and elsewhere. States with
aggressive and proactive renewable energy policies may
also consider the following:
• Offsetting consumption of fossil fuels is a viable
policy goal. Success can be measured in barrels of
oil (or tons of coal) displaced annually by biomass in
the state.
• Success in promoting biomass for energy can be
also measured in annual tons of biomass burned in
the various sectors of the state’s energy economy.
• Another indicator of success is the net reduction
in carbon dioxide emissions, and the associated
climate change benefi t, resulting from displacing
fossil fuel with biomass.
• Federal and state forestry agencies strongly support
the use of biomass for energy because it creates new
markets for low-grade wood wastes, supporting the
forest products industry and the health of the forest
resource.
Where Does Biomass Come From?
The most common type of biomass used in heating
systems is chipped wood, a byproduct that usually
comes from sawmills. Mills have stationery chippers
that chip up slabs and other green (un-dried) wood
that is not suitable for lumber. This material is rarely
allowed to build up on site, but is instead loaded into
tractor trailer trucks that deliver it, either to pulp and
paper mills or to operators of wood energy systems.
Heating system operators like mill residue chips
because they are quite uniform, with few oversized
pieces that might jam machinery.
Some biomass energy facilities use chips that come
from harvesting operations in the woods. Mobile
chippers are used to turn diseased and other “cull”
logs into chips, while most of the tops and branches
stay in the forest to return nutrients to the soil. These
chips are blown from the chipper into delivery trucks,
which deliver them to pulp and paper mills and to
biomass energy users. Because chips from the woods
are less uniform than mill residue chips, energy users
may prefer mill chips, unless there is a signifi cant price
difference.
The third common source of biomass comes from
the waste stream of forest products industries, such
as furniture manufacturers. These wastes are typically
dry, so they include more wood and less water per ton
of biomass. Manufacturing wood wastes are often used
by the plants that produce them, and are less likely to
be available for purchase by energy users. Also, institutional
users tend to avoid dry wood because it comes
with more dust, compared to green wood wastes, and
its much higher level of fl ammability increases fi re risk.
Small biomass energy users rarely burn wood from
WOOD CHIP HEATING SYSTEMS
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