(Listed alphabetically according to main entry)
AGROFUELS: biofuels obtained either as a product or by-product of agriculture. It covers mainly biomass materials derived directly from fuel crops and agricultural, agro-industrial and animal by-products.
- Fuel crops: this term is employed to describe species of plants cultivated in fuel plantations or on farms to produce raw material for the production of biofuel. Fuel crops can be produced on land farms (manioc, sugar cane, euphorbia, etc.), or in marine farms (algae) or fresh water farms (water hyacinths). The land-produced fuel crops can also be classified under: sugar/starch crops, oil crops and other energy crops.
- Sugar/starch crops: are crops planted basically for the production of ethanol (ethyl alcohol) as a fuel mainly used in transport (on its own or blended with gasoline). Ethanol can be produced by the fermentation of glucose derived from sugar-bearing plants (like sugar-cane) or starchy materials after hydrolysis.
- Oil crops: cover oleaginous plants (such as sunflower, rape, etc.) planted for direct energy use of vegetable oil extracted, or as raw material for further conversion into a diesel substitute, using transesterification processes.
- Other energy crops: include a wide variety of plants and specialized crops that have more recently been proposed for possible energy use. Examples would include: elephant grass (Miscanthus), and galinggale (Spartina spp. and Cyperus longus), giant reed (Arundo donax) and reed canary grass (Phalaris arundinacea).
- Agricultural by-products: this is mainly vegetal materials and by-products derived from production, harvesting, transportation and processing in farming areas. It includes, among others, maize cobs and stalks, wheat stalks and husks, groundnut husks, cotton stalks, mustard stalks, etc.
- Agro-industrial by-products: refer to food processing by-products, such as sugarcane bagasse, rice/paddy husks and hulls, coconut shells, husks, fibre and pith, ground nut shells, olive pressing wastes, etc.
- Animal by-products: refer to dung and other excreta from cattle, horses, pigs, poultry and, in principle, humans. It can be dried and used directly as a fuel or converted to biogas by fermentation.
- Biogas: is a by-product of the anaerobic fermentation of biomass, principally animal wastes by bacteria. It consists mainly of methane gas and carbon dioxide.
BIOMASS: all kinds of material coming directly or indirectly from contemporary photosynthesis reactions, such as all vegetal matter and their derivatives: woodfuel, charcoal, paper, dung and a great portion of urban refuse.
- Bioenergy/Biomass energy: covers all energy forms derived from organic fuels (biofuels) of biological origin used for energy production. It comprises purpose-grown energy crops, as well as multipurpose plantations and by-products (residues and wastes). The term by-products include solid, liquid and gaseous by-products derived from human activities. Biomass may be considered as one form of transformed solar energy.
- Bioenergy balance: quantitative summary data on biomass energy production and consumption represented in an energy-balance table and diagram. A bioenergy balance represents an overview of production and consumption of primary and secondary biofuels for a specific area, country or region. All values must have the same units and the same prefix to indicate its magnitude (tera, peta, giga, etc.).
- Forest energy/Wood energy: all energy derived from primary and secondary solid, liquid and gaseous biofuels derived from forests, woodlands and trees. Wood energy represents the energy produced after combustion of woodfuels, such as fuelwood, charcoal, pellets, briquettes, etc., corresponding to the net calorific value (NCV) of the fuel.
- Renewable energy: consists of energy produced and/or derived from sources infinitely renovated (hydro, solar, wind) or generated by combustible renewables (sustainably produced biomass); usually expressed in energy units and, in the case of fuels, based on net calorific values.
BIOFUEL: is the bioenergy carrier, transporting solar energy stored as chemical energy. Biofuels should be considered to be a renewable source of energy as long as there is sustainable biomass production. Biofuels include: woodfuels, agrofuels and municipal by-products.
WOODFUELS: all types of biofuels derived directly and indirectly from trees and shrubs grown in forest and non-forest lands. Woodfuels also include biomass derived from silvicultural activities (thinning, pruning etc.) and harvesting and logging (tops, roots, branches, etc.), as well as industrial by-products derived from primary and secondary forest industries that are used as fuel. They also include woodfuels derived from ad hoc forest energy plantations. Woodfuels are composed of four main types of commodities: Fuelwood (or firewood), Charcoal, Black Liquor and Other.
According to origin, woodfuels can be divided into three groups: Direct woodfuels, Indirect woodfuels, and Recovered woodfuels.
- Direct Woodfuels: consists of wood directly removed from Forests (natural forests and plantations; land with tree crown cover of more than 10 percent and area of more than 0.5 ha); Other Wooded Lands (land either with a tree crown cover of 5-10 percent of trees able to reach a height of at least 5 m at maturity in situ; or crown cover of more than 10 percent of trees not able to reach a height of 5 m at maturity in situ, and shrub or bush cover); and Other Lands to supply energy demands and includes both inventoried (recorded in official statistics) and non-inventoried woodfuels.
- Indirect Woodfuels: usually consists of industrial by-products, derived from primary (sawmills, particle boards, pulp and paper mills) and secondary (joinery, carpentry) wood industries, such as: sawmill rejects, slabs, edging and trimmings, sawdust, shavings and chips bark, black liquor, etc.
- Recovered Woodfuels: refers to woody biomass derived from all economic and social activities outside the forest sector, usually wastes from construction sites, demolition of buildings, pallets, wooden containers and boxes, etc.
- Fuelwood (or firewood): includes “wood in the rough” in small pieces (fuelwood), chips, pellets and/or powder derived from forests and isolated trees, as well as wood by-products from the wood products industry and from recovered woody products.
- Chips: wood that has been deliberately reduced to small pieces from wood in the rough, or residues suitable for energy purposes.
- Wood pellets: can be considered a fuel derived from the auto-agglomeration of woody material as the result of a combined application of heat and high pressure in an extrusion machine.
- Charcoal: refers to a solid residue derived from the carbonization, distillation, pyrolysis and torrefaction of wood (from the trunks and branches of trees) and wood by-products, using continuous or batch systems (pit, brick and metal kilns). It also includes charcoal briquettes.
- Charcoal briquettes: made from wood-based charcoal which, after crushing and drying, is moulded (often under high pressure), generally with the admixture of binders to form artifacts of even shapes.
- Black liquor: is the alkaline-spent liquor obtained from the digesters in the production of sulphate or soda pulp during the process of paper production, in which the energy contents is mainly derived from the lignin removed from the wood in the pulping process.
- Other woodfuels: includes a broad range of liquid and gaseous fuels derived from fuelwood and charcoal basically by pyrolitic or enzymatic processes, such as pyrolysis gases, ethanol, methanol, products of growing interest but up to now not as important as energy commodities as some of the previously described products.
MUNICIPAL BY-PRODUCTS: refer to biomass wastes produced by the urban population and consist of two types of products: solid municipal by-products and gas/liquid municipal by-products produced in cities and villages.
- Solid municipal biofuels: comprise by-products produced by the residential, commercial, industrial, public and tertiary sectors that are collected by local authorities for disposal in a central location, where they are generally incinerated (combusted directly) to produce heat and/or power. Hospital waste is also included in this category.
- Gas/liquid municipal biofuels: correspond to biofuels derived principally from the anaerobic fermentation (biogas) of solid and liquid municipal wastes that may be land-fill gas or sewage sludge gas.
(For further see details see: