After direct solar energy and hydroelectricity, biomass is one of the most important renewable energy forms (wood and dung burning account for about 14% of the world's energy supply) and its use in Canada involves both the oldest and the newest of energy technologies.
In Canada, biomass energy accounts for 540 PJ (petajoules) of energy use. It already provides more of Canada's energy supply than coal (for nonelectrical generation applications) and nuclear power, accounting for 5% of secondary energy use by the residential sector and 17% of energy use in the industrial sector, mainly in the forest industries. Including lumber and pulp and paper, forestry accounts for 35% of Canada's total energy consumption; the forest industries meet more than one-half of this demand themselves with self-generated biomass wastes. The forest industries have been increasing their use of wood wastes that otherwise would be burned, buried or landfilled. Principal uses include firing boilers in pulp and paper mills for process heat and providing energy for lumber drying.
In some areas (eg, BC, Ontario, Québec, PEI, NB), forest industries supply wood waste (known as hog fuel), wood chips and pellets to nearby industrial and residential customers and nonutility electrical generators. In addition, wood is the principal heating fuel for more than 100 000 Canadian homes and a supplemental (though largely decorative) heating source in several million others. Most official estimates understate the residential consumption of wood fuel because a large proportion is harvested and used locally and does not appear in tax records or government statistics.
The other major sources of biomass are agriculture, food-processing residues, industrial wastes, municipal sewage and household garbage. Energy-from-waste projects include steam production for industrial or commercial use or electricity generation in several major metropolitan centres in Canada.
Biomass energy may be in solid, liquid or gaseous form, permitting a wide range of applications. At present, the majority of Canada's biomass energy is supplied in solid form (eg, hog chips, sawdust, pellets, charcoal, garbage), and in liquid form (eg, pulping liquors and ethanol). Other liquid forms of biomass energy include methanol (wood alcohol) and vegetable oils. Landfill gas (methane) from the anaerobic digestion of municipal solid waste in refuse sites is becoming more widespread in use and currently accounts for 100 MW.
When methanol or ethanol is mixed with gasoline, the product is sometimes called "gasohol." Methanol, produced from wood and forest waste by a distillation process, may provide an alternative fuel for transportation and industry at prices competitive with fuels from bitumen and coal liquefaction. Ethanol, although it is also a viable transportation fuel, is more expensive to produce when potential food supplies such as corn and wheat are used. However, ethanol made from biomass sources such as food and agricultural wastes has the potential to be cost-competitive with methanol and gasoline.
The emphasis of much current research is in the conversion of biomass to alcohol for use as a transport fuel (to extend or replace gasoline and diesel oil). For example, at present the production of alcohol from cellulose is a 2-stage process: converting cellulose into sugars and then the sugars into alcohol through fermentation. New, genetically engineered strains of bacteria have recently been made which show promise for combining these functions to make possible a one-step production process for alcohol from cellulose.
The gaseous form of biomass energy is called biogas, a methane-based gas with a low heating value. It is typically derived from the anaerobic (ie, without the presence of oxygen) digestion of organic material, such as municipal sewage or animal manure.
A staged program of development of forest biomass is advocated to increase the role of bioenergy in Canada's primary energy mix by the year 2000. The first stage would use all logging and mill wastes created by existing forest industries. This material is being increasingly used as a substitute for fossil fuels. Economics are usually favourable because the material is concentrated and the costs of handling and transport are carried by the primary forest product of which this material is the residue. The second stage would be the use of residues and residuals not currently used in conventional forest-harvesting operations.
Residues are tree components left behind after merchantable material (eg, sawtimber, pulpwood) has been removed. Residuals are unmerchantable species of trees as well as defective, dying and dead trees currently unusable. The forest industry might use this material for producing steam or steam-generated electricity for on-site consumption; or, with the advent of power generation deregulation, for sale to the power grid. A final stage would be to give serious consideration towards the establishment of energy plantations of fast-growing hybrid species and grasses.
Harvesting energy from forest biomass could be an economic boon for new industries: all cellulosic material now thrown away (ie, branches, bark, boles and stumps, and crooked, diseased, insect-infested, fire-damaged, dying and dead trees) could become valuable energy products. Use of forest biomass for energy also affords the opportunity to liquidate low-grade stands and replace them with productive stands of the more valuable species. In some areas (eg, BC), it has been estimated that forest-industry wastes alone could provide enough solid and liquid fuels to replace much of the current oil consumption, once the energy conversion technologies are proven to be economic.
In other parts of Canada - eg, the Prairie provinces and eastern Canada - energy plantations would be needed to provide enough biomass for significant oil displacement. Marginal and sub-marginal agricultural land, as well as nonagricultural land (eg, wetlands), could be used for high-yield "forest farming" with rotations of less than 10 years between harvests (see SILVICULTURE). The tree species under trial in Canada are primarily poplar and willow hybrids and include larch, green ash, willow, alder and soft maples. Through selection of species, provenances and phenotypes, and by cloning, it is possible to increase yields greatly and to develop disease resistance and frost hardiness.
includes animal manure, cellulosic crop residues, fruit and vegetable culls and food-processing effluent. Potential energy crops include high-yielding, high-carbohydrate crops such as switchgrass and vegetable-oil crops such as canola and sunflower, and hydrocarbon plants such as milkweed and gumweed. The potential for agriculture biomass derived energy is less than that of forest derived biomass in Canada. Most agricultural residues have alternative uses as animal fodder or soil conditioners and typically have a much lower energy intensity than wood (ie, 1 m3 of wood contains as much energy as 5-10 m3 of baled field residues).
Agricultural biomass is also usually only available at one time of year, while forests can be harvested year-round. The average inventory of biomass on forested land is about 20 times the annual yield from cropland. However, agricultural biomass does have a place in farm-scale or localized operations. Biogas from animal manures can be used to heat farm buildings or, if scrubbed and compressed, to power farm vehicles. The use of animal and food-processing wastes can abate pollution and reduce disposal problems as well as produce energy. Straw can be burned in a specially designed furnace to dry grain and heat farm buildings, or converted ethanol for transportation fuel. The development of vegetable oils as fuels in farm diesel engines is undergoing continual development.
Various federal government departments and federal and provincial research organizations have studied proposals to develop the potential of biomass energy. Two notable examples are ENFOR, the federal Energy from the Forest Program, and the Bioenergy Development Program of National Resources Canada. Both programs are financially supported by the federal interdepartmental program of Energy Research and Development.
Canada is a signatory to the International Energy Agency Bioenergy Agreement, which promotes cooperation and collaboration among the 16 member countries. Information is exchanged, new and promising technologies are tested and reported on, and avice is tendered to policymakers on the potential of increasing the proportion of energy generated using biomass.
The main problems facing expansion of biomass energy are the relatively high costs of new facilities and the need to make the industry truly renewable. The cost barrier may be overcome by government policy and rising prices of conventional energy sources. However, careful attention is also needed for problems of reforestation, land use, water use, soil quality, erosion and pollution. Producing energy, in addition to lumber and paper, could put new stress on the sustainability of a forest resource base that is already endangered by past practices of the forest industries. Biomass energy must be farmed, not mined; otherwise it will merely join coal, oil and natural gas as yet another nonrenewable energy source.
Author W. H. CRUICKSHANK, J.E. ROBERT AND C.R. SILVERSIDES
Links to Other Sites
Re-Energy.ca is a hands-on renewable energy learning experience. Building working models of renewable energy technologies allows students in grades 7 through 12 to discover the fundamental principles of biology, chemistry and physics, and to explore the application of science and technology to social and environmental issues.
Vegetable Oil Industry of Canada
The website for the Vegetable Oil Industry of Canada, an industry group representing oilseed growers, processors, suppliers, and related sectors across Canada.
UBC launches green energy project
A CBC News story about a green energy project that uses biofuel, including wood chips and trees killed by disease, to generate heat and power for the University of British Columbia. Includes an illstration of the components of this system.