|Monday, 2020-10-19, 10:46 PM||Main | Registration | Login|
Video of the Month
Total online: 1
Biofuels and Bioenergy
BIOFUELS AND BIOENERGY
Canada’s potential for producing fuels and generating energy from biomass is both very large and underutilized. However, the feasibility of using biomass as a source of fuel for cars, factories and electricity generation depends on the availability of appropriate technologies and the harvesting of sometimes remote biomass resources. Currently, Canada meets about six per cent of its total energy needs from biomass, compared to three per cent for both the European Union and the United States.
Technologies through which biomass can be converted into fuels and energy include fermentation, combustion, anaerobic digestion, pyrolysis, thermal depolymerization and gasification. Some of these technologies and related processes are described below to show how they work.
Biomass for Heat and Power
Burning biomass is called "direct combustion.” Woodstoves and fireplaces use direct combustion to heat homes. New technologies have made many wood and biomass burning stoves very efficient. Fuel for these stoves includes everything from wood and wood chips to biomass particles, pellets and fire logs made from coffee grinds. While the amount of trace gases (including CO2) and particles emitted from woodstoves varies widely among different models, many Canadians use them as an alternative to oil and gas furnaces for space heating or to fossil fuel-fired plants as a source of electricity.
Biomass direct combustion is also used to generate steam and electricity (or, more simply put heat and power). For this purpose, dried organic material is burned to boil water, and the resulting stream process heat that forces a turbine to spin and generate electricity. In the United States, direct biomass combustion currently generates more than 7,500 megawatts of electricity – enough to power several million households.
In Canada, direct combustion is used to generate heat and electricity in communities across the country. For example, in Charlottetown, Prince Edward Island, a wood-fired district heating system has been supplying heat to 15 buildings, city hall, two churches, three hotels and a fire hall.
Hydro-Québec gets 28 megawatts of power from the wood-fired Chapais Generating Station in Chapais, Québec. The Williams Lake power plant in Williams Lake, British Columbia, burns wood waste from forestry operations in the area to fuel its 60 megawatt operation. In the Town of Ajax, a biomass-powered district energy system provides energy to the community centre, Ajax-Pickering Hospital, the Ajax Works Department and more than a dozen industrial customers.
Most biomass can generate energy from direct combustion, but some biomass sources are avoided because they produce large amounts of ash that can foul boilers, reduce efficiency and increase costs. Similarly, wet biomass can result in a large amount of energy being wasted in boiling off the moisture before the biomass can be burned.
Biomass can also be converted into clean and efficient fuels that can be indirectly used to drive generators, fuel cells, engines and other energy conversion devices, and to produce power. Pyrolysis and advanced gasification technologies transform organic materials into crude oil (bio-oil) and "synthesis gas” (syngas), respectively. Thermal depolymerization produces true hydrocarbon oil comparable to high-quality heating oil. These technologies generally have greater conversion efficiency and use a wider variety of biomass than combustion technologies.
Pyrolysis converts biomass to fuel by heating it in an oxygen-free tank. The gas produced is then quickly cooled to a liquid and a solid charcoal. The liquid can be burned for energy or used to produce chemicals that can replace petrochemicals. Renewable fuels produced by pyrolysis can be more easily stored, transported and burned than can solid biomass.
Gasification is a similar process to pyrolysis, but introduces oxygen as the biomass is heated. The result is a cleaner fuel called syngas. Syngas contains carbon monoxide and hydrogen, as well as nitrogen, but it still burns with fewer emissions than do fossil fuels. Syngas can be used in place of natural gas to generate electricity, or as a raw material to produce chemicals (e.g., ammonia) and liquid fuels (e.g., methanol).
Co-firing is another method of reducing as emissions and the environmental impacts of fossil fuel-powered generators. Rather than heating the generator boilers in electricity plants with coal alone, the co-firing process mixes dried biomass into the fuel. Co-firing helps reduce the amount of coal needed to produce electricity.
Does Canada Have a "Green Advantage”?
Canada is home to seven per cent of the world’s land mass and 10 percent of its forests. Most of the country’s biomass production takes place in large forests.
The BIOCAP Canada Foundation estimates that, if gathering and processing this widely distributed energy resource were economically feasible, there may be enough unused biomass from Canada’s forestry and farming operations alone (crop residues, unused tree branches, mill waste, etc.) to provide almost 27 per cent of the country’s current energy needs. The university based research organization also calculates that a 25 per cent increase in today’s tree and crop production could meet a further 15 per cent of the energy demand now being filled by fossil fuels.
These numbers reflect the total biomass potential of Canada’s vast forests and farmlands. They do not take into account the difficulties associated with collecting this material, the shortcomings of the technology, the economics of processing it, the related pollution problems, and other environmental and economic issues associated with the use of biomass as a source of energy.
Biomass to Fuel Vehicles
People have been fermenting plant sugar into ethanol almost since the beginning of recorded history. New biotechnologies have sped up these processes. Today’s novel enzymes make it possible to generate alcohol from plants several thousand times more efficiently than the earliest brewers and distillers managed it. Ethanol burns quickly and cleanly and can serve as a renewable fuel for transportation and other uses. Most of the ethanol fuel now available in Canada is produced from corn. The starch in the corn is chemically processed into glucose (a simpler sugar0, which, in turn, is fermented into alcohol using yeast. About 225 million litres of ethanol is now blended into gasoline (as a five to 10 per cent additive) and sold at more than 600 retail stations across Canada each year. In October 2000, the federal government announced plans to increase ethanol production in Canada by 750 million litres per year over the next five years, which would increase bioethanol production from about 0.6 per cent to 2.5 per cent of the total gasoline use in Canada. Canadian ethanol production currently consumes more than 17 million bushels of corn every year. One major by product of this ethanol production is a high-quality livestock feed that is more nutritious than the original corn.
The cost and availability of suitable crops are considered major hurdles to the larger commercial development of bioethanol in Canada. Additionally, the environmental benefits of converting corn and grain to ethanol (e.g., lower greenhouse gases) can be compromised by the large amounts of energy, fossil fuels nd fertilizer needed to form these crops.
New biotechnology that is promising large-scale conversion of the tough, fibrous parts of plants (i.e., the cellulose in stalks, corn cobs and straw) to bioethanol may be more environmentally attractive than current technologies. Many of the technologies needed to manufacture cellulose-based ethanol on a commercially viable scale are still in development. Iogen Corporation of Ottawa has become a world leader in the development of this technology.
Meanwhile, fatty acids or oils from renewable plant and animal sources can be converted into a clean-burning fuel known as biodiesel. These organic oils – from seeds, corn, canola, animal separated to isolate the combustible compounds that make up the fuel. According to the Canadian Renewable Fuels Association, biodiesel, as a blend or by itself, can be used in conventional diesel engines to significantly reduce some pollution emissions. Producing the fuel does not generate any net CO2 emissions, and the fuel itself is considered to be biodegradable.
Fuelled by Biodiesel
Costs are still a significant barrier to large-scale commercial production and use of biodiesel. Estimates by the US Department of Energy suggest that biodiesel costs from US$1.95 to US$3 per gallon (depending on the feedstock and the supplier), compared to the current price of regular diesel of about US$1.50. Diesel blends using 20 per cent biodiesel are expected to cost US$0.30 to US$0.40 more per gallon than diesel, the department says. An important factor here is the equalization of incentives and enabling policies for biobased products – starting with energy – that put biomass on a level playing field with fossil fuels, which are still subsidized and not held accountable for all of the environmental costs they create.
According to the American Biodiesel Association, despite the higher cost, biodiesel users in the United States already include the US Postal Service and the US Departments of Energy and Agriculture, as well as almost 100 other public and private fleets in the country.
The use of biodiesel in Canada is problematic in the winter months. In cold weather biodiesel thickens more quickly than conventional diesel. For the time being, biodiesel can be used as an additive in up to five per cent of the conventional diesel fuel blend until an optimum blend ratio can be found that will improve biodiesel’s winter performance.
In Canada, very little biodiesel is produced commercially; however, an increase is expected over the next few years. Demonstration projects to test the viability of biodiesel as a fuel for city transit and public words fleets have been established in a number of municipalities, including Kingston, Montreal, Saskatoon, Brampton, Guelph, Vancouver, Whistler, Halifax and Toronto has developed a new chemical technology that produces biodiesel from biomass at a cost 40-50 per cent cheaper than other biodiesel processes. The company is planning to launch its first commercial-scale biodiesel production facility (60 million litres per year) in 2004.
Gas from Municipal and Farm Waste
Biogas – a mixture of methane and CO2 – is a renewable fuel that can be produced from organic waste, Biogas is made by bacteria that degrade biological material in the absence of oxygen in a process known as anaerobic digestion. Anaerobic digestion can result in the creation of gas from organic material. It usually occurs naturally in marshes, rubbish dumps, septic tanks and the digestive systems of ruminants, such as cattle and sheep.
The disposal of farm manure and municipal solid waste presents serious environmental problems and expense for rural and urban communities. Instead of being disposed, these wastes can be used in the production of biogas. Anaerobic digestion processes have been applied to poultry and cattle manure, hog farm effluent and food processing waste. Biogas from a number of landfill sites in Canada is now used to drive gas turbines for power generation. This not only makes electricity, but also burns methane – a greenhouse gas 21 times more potent than CO2 – before it is released into the atmosphere.
The municipality of Kitchener – Waterloo, for example, together with Toromont Energy, use naturally created landfill gases – gases that were once simple burned off – to produce electricity. A network of subterranean pipes collects the gases from the landfill and uses them to fuel an electrical generating station.
In Lethbridge, Alberta, ECB Enviro is building a pilot facility that will produce biogas energy (as well as treated water and fertilizer) using pig farm manure generated by area hog operations. The company expects the plant, which began construction in 2003, to use 100,000 tonnes of manure per year, while generating enough electricity for about 900 homes.
|Copyright gogreencanada © 2020 | Free web hosting — uCoz|