Glossary

Agro-energy	Energy derived from purposely-grown crops, and from agricultural and livestock by-products, residues and wastes.
Ash	The non-combustible components of fuel.
Ash fusion temperature	The temperature at which ash melts.
Biodiesel	Biofuel produced from various feedstocks including vegetable oils (such as palm oil, oilseed, rapeseed, jatropha and soybean), animal fats or algae.
Bioenergy	All types of energy derived from biofuels including wood energy and agro-energy.
Bioethanol	Biofuel produced from sugar-rich plants (such as sugar cane, maize, beet, cassava, wheat, sorghum) or starch.
Biofuel	Any solid, liquid or gaseous fuel produced from biomass.
Biogas	A gas produced from biomass, usually combustible.
Biomass	Organic matter available on a renewable basis. Biomass includes forest and mill residues, agricultural crops and wastes, wood and wood wastes, animal wastes, livestock operation residues, aquatic plants, fast-growing trees and plants, and municipal and industrial wastes.
Biorefineries	A new generation of refineries expected to produce not only power and heat, but also transportation fuels and industrial products.
Black liquor	A liquid woodfuel, a by-product of the pulp industry.
Boiler horsepower (BHP)	The equivalent of heat required to change 15.6 kg (34.5 lb) per hour of water at 212°F (100°C) to steam at 212°F (100°C). One BHP equals 9.81 kW (33,479 Btu/h).
Bottom ash	Ash that collects under the grates of a combustion furnace.
Bridging	Wood fuel in a storage bin, hopper, or conveying system that supports itself although the fuel beneath has moved. Bridging is one of the most common problems associated with wood-handling systems.
British thermal unit (Btu)	A standard unit of energy equal to the heat required to increase the temperature of 1 lb (0.45 kg) of water 1°F (0.56°C).
Calorific value:	The potential heat production value of a wood source that depends on the cellulose-lignin ratio, the percentage of extractives, and the moisture content.
Carbon cycle	The process of transporting and transforming carbon throughout the natural life cycle of a tree from the removal of CO2 from the atmosphere to the accumulation of carbon in the tree as it grows, and the release of CO2 back into the atmosphere when the tree naturally decays or is burned.
Carbon sequestration	The provision of long-term carbon storage in the terrestrial biosphere, underground, or oceans, so that the build-up of carbon dioxide (principal greenhouse gas) concentration in the atmosphere reduces or slows.
Cellulose	Principal organic constituent in land plants, found in wood in association with hemicellulose and lignin.
Char	Carbon-rich combustible solids that result from pyrolysis of wood in the early stages of combustion. Char can be converted to combustible gases under certain conditions or burned directly on the grate.
Chipper	A large device that reduces logs, whole trees, slab wood, or lumber to chips of more or less uniform size. Stationary chippers are used in sawmills, whereas trailers mounted whole-tree chippers are used in the woods.
Chips	Woody material cut into short, thin wafers.
Clinker	A slag-like material formed in the combustion process when the temperature of combustion exceeds the ash fusion temperature of the fuel.
Cofiring	Biomass cofiring refers to combustion of biomass along with coal in a thermal power plant to reduce the amount of carbon dioxide released. Co-firing is the process of replacing part of the fossil fuel supplied to a power station or boiler with a 'carbon lean', renewable alternative.
Cogeneration	The sequential production of electricity and useful thermal energy from a common fuel source; Combined heat and power (CHP).
Combined cycle	Two or more generation processes in series or in parallel, configured to optimise the energy output of the system.
Combined heat and power (CHP)	The simultaneous production of heat and mechanical work or electricity from a single fuel.
Combustion air	Air that is used for the burning of a fuel.
Combustion efficiency	The efficiency of converting available chemical energy in the fuel to heat. It measures only the completeness of fuel combustion that occurs in the combustion chamber.
Combustor	The primary combustion unit, usually located next to the boiler or heat exchanger.
Coppiced	Regenerated by producing multiple new shoots from a stump left after harvest.
Cyclone separator	A flue-gas particulate-removal device that creates a vortex to separate solid particles from the hot gas stream.
Decentralised supply	Distributed electricity supply where power is generated locally rather than distributed by a grid
Densified biomass fuel	Biomass material that has been dried and compressed to increase its density (e.g., pellets).
District energy system	A system using central energy plants to meet the heating or cooling needs or both of residential, institutional, commercial, and industrial buildings.
Energy crop	A plant grown to produce biofuels, or directly exploited for its energy content. Commercial energy crops are typically densely planted, high yielding crop species such as Miscanthus, Salix or Populus.
Excess air	The amount of combustion air supplied to the fire that exceeds the theoretical air requirement to give complete combustion.
Feedstock	Any biomass destined for conversion to energy or biofuel. For example, corn is a feedstock for ethanol production and soybean oil is a feedstock for biodiesel. Cellulosic biomass has the potential to become a significant feedstock source for biofuels.
Feedstock	Any material that is converted to another form or product.
First-generation biofuel	Fuel produced from purposely grown crops.
Flue gas	All gases and products of combustion exhausted through the flue or chimney.
Fly ash	Ash transported through the combustion chamber by the exhaust gases and generally deposited in the boiler heat exchanger.
Forest biomass	Any biomass found in forests including trees, leaves, branches, roots. Specific types of biomass targeted for use in energy systems include tops and branches of trees left after timber harvests, poor quality trees in managed forests, trees removed during land clearing operations, wood waste from urban areas, and wood residues produced by sawmills.
Forest cover	Percentage of land within a specific area covered by forests.
Fossil fuel	A non-renewable energy source produced by the remains of living organisms that built up underground over geological periods in liquid (oil), solid (coal, peat) and gaseous (natural gas) forms.
Fuel cell	A cell similar to a battery that uses an electrochemical reverse electrolysis process to directly convert the chemical energy of a fuel (gas, propane) into electricity, heat, and water.
Fuel crop	See Energy crop.
Fuelwood	Wood in the rough (such as chips, sawdust and pellets) used for energy generation.
Gaseous woodfuel	Gas produced from the gasification of solid and liquid woodfuels.
Gasification	Conversion of solid fuel into gaseous fuel.
Gasifier	Any device that changes solid biomass into a gaseous fuel.
Gasifier	Plant or equipment used for converting solid fuel into a gaseous fuel, generally rich in carbon monoxide and hydrogen.
Greenhouse gas	Chemical compounds in the atmosphere that trap sun radiation and heat.
Grid	An electric utility company’s system for distributing power.
Hog fuel	Fuel generated by grinding wood and wood waste for use in a combustor.
Hydrocarbon	Any chemical compound containing hydrogen, oxygen, and carbon.
Jatropha	Mainly Jatropha curcas, an evergreen shrub found in Asia, Africa and the West Indies. Its non-edible seeds contain a high proportion of oil which can be used to produce biodiesel.
Kilowatt	A standard unit for expressing the rate of electrical power and useful heat output. The symbols e and th stand for electrical and thermal, respectively.
Lignin	Lignin is a complex chemical compound most commonly derived from wood, and an integral part of the secondary cell walls of plants. Highly lignified wood is durable and therefore a good raw material for many applications. It is also an excellent fuel, since lignin yields more energy when burned than cellulose. Lignin softens when heated (with steam) and assists in wood binding into hard and durable pellets.
Liquid biofuel	Fuel of biological origin that is used in liquid form, such as biodiesel and bioethanol, currently manufactured predominantly from food crops including oil-palm, sugar cane, maize, rapeseed, soybeans, and wheat.
Liquid woodfuel	Black liquor and ethanol, methanol and pyrolytic oil.
Live-bottom trailer	A self-unloading tractor-trailer with a hydraulically operated moving floor used to remove biomass fuel.
Metering bin	A bin in the fuel-feed stream that allows a precise feed rate of the fuel to the fire.
Mill chips	Wood chips produced in a sawmill.
Moisture content	The weight of the water contained in the biofuel, usually expressed as a percentage of weight.
Municipal by-products	Waste products such as sewage sludge and landfill gas, as well as municipal solid wastes.
Non-renewable fuel	Fuel from a finite resource that will eventually dwindle and become too expensive or too environmentally damaging to retrieve. Includes fossil fuel from coal, petroleum and natural gas and nuclear energy.
On/off fuel feed	A fuel-feed system that transports fuel to the grates on an intermittent basis in response to boiler water temperature and load variations.
Over-fire air	Combustion air supplied above the grates and fuel bed.
Particulates	Minute, solid, airborne particles that result from biomass combustion.
Proximate Analysis	Biomass fuels are characterized by what is called the "Proximate and Ultimate analyses". The "proximate" analysis gives moisture content, volatile content (when heated to 950 C), the free carbon remaining at that point, the ash (mineral) in the sample and the high heating value (HHV) based on the complete combustion of the sample to carbon dioxide and liquid water.
Pulpwood	Wood assortments used in making paper.
Pyrolysis	A process of reduction at oxygen-starved conditions at high temperatures (greater than 200° C), involving the physical and chemical decomposition of solid organic matter by the action of heat into liquids, gases, and a carbon char residue.
Renewable energy	Energy produced from sources that can be renewed indefinitely, for example, hydro-, solar, geothermal, and wind power, as well as sustainably produced biomass.
Residence time	The length of time the fuel remains in a combustion zone.
Roundwood	Wood in its natural state as felled, with or without bark.
Sawnwood	Wood in sawn form.
Seasonal efficiency	The ratio between the total useful energy delivered to the thermal load over the full operating season and the total potential energy within the fuel burned over the period.
Second-generation biofuel	Liquid fuels produced from cellulosic materials, crop residues and agricultural and municipal wastes (MSW).
Solid biomass	Wood, wood waste and other solid waste.
Steady-state efficiency	Ratio of output-to-input energy when combustion system is operating under design conditions.
Steam turbine	A device for converting energy of high-pressure steam into mechanical power which can then be used to generate electricity.
Sustainable	An ecosystem condition in which biodiversity, renewability, and resource productivity are maintained over time.
Syngas	Short for synthetic gas. A mixture of carbon monoxide and hydrogen resulting from high temperature gasification of organic material such as biomass. After clean-up can be used to synthesise organic molecules such as synthetic natural gas or liquid biofuels.
Traditional biomass	Woodfuels, agricultural by-products and dung burned for cooking and heating purposes. In developing countries, still widely harvested and used in an unsustainable and unsafe way. Mostly traded informally and non-commercially.
Turndown ratio	A ratio found by dividing the maximum energy output by the minimum output at which efficient, smoke-free combustion can be sustained.
Under-fire air	Combustion air added under the grates.
Whole-tree chips	Wood chips produced in the woods by feeding whole trees or tree stems into a mobile chipper that discharges directly into a tractor-trailer.
Wood energy	Energy derived from fuelwood, charcoal, forestry residues, black liquor and any other energy derived from trees.
Wood energy feedstocks	Wood and biomass recovered from forests and trees for use in creating fuel.
Wood gasification	The process of heating wood in an oxygen- starved chamber until volatile pyrolysis gases (e.g., CO, H2, O2) are released from the wood. The gases emitted are low- or medium-energy-content gases that can be combusted or used to produce chemicals in various ways.
Wood pellets	Small particles used for energy generation made of dried, ground and pressed wood.
Wood residues	Wood left behind in the forest after forest harvesting, and wood by-products from wood processing, such as wood chips, slabs, edgings, sawdust and shavings.
Woodchips	Woody material cut into short, thin wafers.
Woodfuel	Fuel from wood sources including solids (fuelwood and charcoal), liquids (black liquor, methanol, and pyrolitic oil) and gases from the gasification of these fuels.

Aligned Energy

Sustainable biomass for power generation...