A | B | C | D | E | F | G | H | I | J | K | L |
M | N | O | P |
Q | R | S | T | U | V | W | X | Y | Z
A
Accumulator tank
A large, well insulated hot water tank, plumbed in to take heat
directly from a boiler. They are often used to help smooth some of
the peaks and troughs in demand.
Arboricultural arisings
Woody material produced during arboriculture (see below).
Arboriculture
The management of individual trees or groups of trees primarily
for their amenity value (e.g. timber).
Archimedes screw (auger)
Rotating spiral of metal inside a tube used in boiler feed
mechanisms for wood chips or pellets, and in automated ash
extraction mechanisms.
Ash
The non-combustible, mineral content of biomass. During burning
ash is left behind in, or under, the grate or combustion region, or
at the bottom of a gasifier. Fly ash is the very small particles of
ash that are carried out of the system along with the flue
gases.
Auger
See archimedes screw.
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B
Biodiesel
Diesel made from biomass, such as oilseed rape.
Bioenergy
Energy produced from biomass. Sometimes the potential energy
within biomass.
Bioethanol
Ethanol made from biomass.
Biofuel
Liquid fuel made from biomass, such as biodiesel or
bioethanol.
Biomass
Biological material such as wood, miscanthus, dung or straw.
Boiler
Device for extracting heat energy from fuel to provide hot water
or steam.
Brash
The branch-wood and leaf material that is generally too small in
diameter to be considered part of the timber product from a
harvesting site.
Briquette
Large cylindrical section of compressed dried sawdust. Used as
fuel in a similar way to logs.
Bulk density
The weight per unit volume for a solid materials.
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C
Calorific value (CV)
The amount of heat produced by the complete combustion of a unit
weight of fuel, often expressed in megawatt hours per cubic metre
(MWh/m3).
Carbon cycle
The cycle by which carbon in various forms moves between the
Earth's atmosphere, hydrosphere (seas and oceans), lithosphere
(rocks, soils and mineral deposits, including fossil fuels) and
biological material including plants and animals.
Carbon emissions
The level of carbon, usually in the form of carbon dioxide,
exhausted into the atmosphere by a process.
Carbon neutral (low carbon)
Processes that have a zero or very low contribution to
atmospheric carbon.
Chipper
Machine, mobile or static, used for the production of
woodchips.
Chipping
The process of making small fragments of timber (usually to a
specified size) by passing larger logs or pieces of timber through
a chipper.
Chips
See wood chips.
Clear felling
A harvesting operation that removes all the trees from a given
area.
Clones
Genetically identical trees propagated commercially because of
desirable properties. Often used in, for example, short rotation
coppice.
Combined heat and power (CHP)
Systems that derive and utilise both thermal and electricity
energy from a given fuel source.
Combustion
The process of converting fuel into heat energy.
Coppice
The practice of harvesting the above ground part of a tree for
timber and allowing the new shoots to re-grow in a cycle normally
extending over a number of years.
Crop
In forestry, collectively describes the trees in a productive
woodland.
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D
District heating scheme
System by which heat is distributed via underground pipe-work
from a single centralised boiler to a number of domestic or
commercial units.
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E
Embedded energy
The total amount of energy used in the production of a fuel or
product (e.g. planting, harvesting, processing, transport).
Energy crop
Typically a crop of trees, woody plants or grasses grown for the
purpose of providing biomass for energy.
Energy density
The amount of energy stored per fuel unit, by volume or
mass.
ESCo
Energy services company. Sells heat to the customer rather than
a boiler and/or fuel.
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F
Felling
Cutting down standing trees.
Flue
A chimney-like tube for the venting of gases and vapour from the
boiler after combustion.
Forward
The process of extracting harvested timber from a woodland
whilst keeping the timber off the ground (involving a tractor and
trailer unit known as a forwarder).
Fossil fuels
Fossilised fuel (e.g. coal, mineral oil and natural gas) that,
when burnt, releases carbon into the atmosphere. Burning fossil
fuel can contribute to an increase in atmospheric greenhouse
gases.
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G
Gas turbine
Device for turning thermal energy from gasified biomass into
electrical energy.
Gasification
Conversion of solid material such as woodchip into a gas for use
as a fuel.
Global warming
The rise in the earth's atmospheric temperature. Consider to be
partly due to man-made atmospheric pollution contributed to by the
use of fossil fuels.
Greenhouse gas
Gas capable of absorbing infra-red radiation before it escapes
the earth's atmosphere (e.g. carbon dioxide, methane).
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H
Hag
The branch wood and leaf material that is generally too small in
diameter to be considered part of the timber product from a
harvesting site.
Harvesting
In forestry, the practice of felling and removing trees from a
woodland.
Haulage
The movement of material (e.g. timber) from site to site,
usually by lorry.
Heat exchanger
Device, within a boiler or water tank, to transfer heat from one
system to another.
Hopper
Fuel storage container usually adjacent to a boiler house.
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K
Kilowatt
A unit of energy equal to 1000 watts.
Kilowatt hour (kwh)
Energy unit equal to one kilowatt of power used for one hour. A
single bar electrical fire would typically use about 1 kwh of
electricity if operated for 1 hour.
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L
Load
The energy generated by a boiler.
Log
Sections of a tree or branch cut to a length. When cut for use
in a stove or boiler, the length is specified.
Lop & top
Alternative term for Brash.
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M
Megawatt (Mw)
Unit of energy equal to one million watts, or one thousand
kilowatts. Sometimes MWe is used.
Megawatt hour (Mwh)
Measure of energy production or consumption equal to one million
watts produced or consumed for one hour.
Miscanthus
A grass often planted as an energy crop.
Microgeneration
The small scale production of heat and/or electricity, usually
from a low carbon source. The Energy Act 2004 gives maximum size
limits of 50 kW electricity and 45 kW thermal.
Moisture content
The proportion of water in a sample of biomass, defined as the
weight of water as a percentage of the weight of biomass.
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O
Oven dry tonne (odt)
One tonne of material (woodfuel) at 0% moisture content.
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P
Pellets
See wood pellets
Pyrolysis
The chemical decomposition of wood chips by the action of heat
to produce a liquid fuel.
Pyrolysis oil
Oil produced by fast pyrolysis of biomass. A dark brown, mobile
liquid containing much of the energy content of the original
biomass, with a heating value about half that of conventional fuel
oil.
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R
Renewable energy
Energy that has been obtained from a potentially infinite
resource, such as wood, sunshine or the wind.
Renewable fuel
Fuel that is considered to be an infinite resource if its source
is sustainably managed. Examples include woodfuel, miscanthus or
the wind.
Rotation
The period of growth of a forest crop before it is considered
mature.
Roundwood
See small round wood.
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S
Short rotation coppice
The practice of growing and harvesting a crop (usually willow)
just above ground and then allowing new shoots to re-grow from the
harvested stumps (also known as stools) in a short cycle (3 to 5
years).
Short rotation forestry
The practice of growing a specific crop of trees, usually
poplar, for biomass over a relatively short rotation (usually no
more than 15 years).
Silo
Fuel storage container usually adjacent to a boiler house; can
be below ground.
Silviculture
The care and cultivation of forests.
Skid
The process of extracting timber from a woodland site by winch,
usually dragging part of the timber on the ground.
Small round wood
Small trunk or branch wood of diameter 7-14cm.
Solid fuel
Fuel in solid form, typically wood or coal, often used in
stoves, open fires and some boilers.
Stand
A group of plants (e.g. trees).
Steam turbine
Device for converting thermal energy from steam into electrical
energy.
Stove
Device for use indoors to provide room heat, usually from solid
fuel.
Sustainable
Meeting the needs of the present without compromising the
ability of future generations to meet their needs.
Sustainable forest management
The process of managing forests to provide goods and services
without degradation of the site quality, and without a decline in
the yield of goods and services over time.
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T
Thermal power station
A power plant in which water is heated, turns into steam which
spins a turbine and drives a generator.
Thinning
The process of removing selected trees from an immature woodland
to allow other trees to increase in diameter.
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W
Watt
A unit of energy defined as one joule transferred or dissipated
in one second.
Wood chips
Small fragments of timber sliced from a larger log or piece of
timber by a chipper, usually to a specified size.
Wood pellets
Small diameter cylindrical section of compressed sawdust formed
by passing dry sawdust under high pressure through a dye. Usually
between 6 to 8mm in diameter and 10 to 30mm in length.
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Y
Yield
The timber volume increment of a specified area of woodland over
a specified time. Usually expressed in cubic meters per hectare per
year.
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