Bioenergy or biomass energy includes any solid, liquid or gaseous fuel, or any electric power generation that uses biomass feedstock (any material derived from plant or animal organic material) as a fuel source.
The biomass feedstock can be directly obtained from vegetation or indirectly from animal or vegetation-derived waste or waste products such as straw and animal manure.
Biogas is a mixture of gases produced by anaerobic (in the absence of oxygen) digestion of organic material: predominantly methane gas with lesser amounts of carbon dioxide and other trace gases (depending on the source of the feedstock).
Biogas can be utilized for heat or electricity providing the quality of gas is acceptable. Contaminants such as moisture, sulphur and carbon dioxide may cause serious mechanical and environmental problems if not removed; therefore, a rigorous cleanup of the biogas is required prior to use.
Economics of biogas
Biogas technology is at the market entry level and therefore, the cost to install an anaerobic digester for animal waste is still quite high (approximately $4,500/kW in 2007). A subsidy would most likely be required in order to make projects economical at this time.
We have supported research projects on low-temperature anaerobic digestion for processing hog manure.
One such operation is just outside Teulon, Manitoba. This project may eventually set the stage for a practical, low-cost methane production system that reduces odours from hog operations, lowers greenhouse gas emissions, powers space and water heating systems, and even generates electricity for on-site use or for selling to our grid.
Biomass combustion is a process which burns biomass for fuel in a special designed boiler, furnace or wood stove. These combustion chambers can be specifically designed to reduce emissions and airborne particulate.
Biomass fuels typically used for combustion normally originate from forest and agricultural residues such as bark, branches, straw, sawdust, wood chips or pellets. The process of combustion converts the biomass fuel into many forms of useful energy including hot air, hot water, steam and electricity.
Biomass can be burned alone or co-fired with another fuel, such as coal. The method of direct combustion is well established, but co-firing combustion remains at a less mature stage of development.
Although burning alone with biomass is seen as a carbon-neutral process, concerns surrounding air emissions, water consumption, and competition between food and fuel uses need to be evaluated.
Economics of biomass
After hydroelectricity, biomass combustion technology is by far the most deployed and utilized renewable energy resource in Canada.
The cost of electricity, without incentives, is between 10¢ to 12¢/kWh (2007 CDN$) for direct combustion compared to 3¢ to 5¢/kWh (2007 CDN$) for co-fired combustion (assuming that both the existing plant is fully depreciated and the cost of coal is $1.50/MMBtu).
We are currently evaluating the potential for utility-scale electrical generation based on agricultural and industrial solid biomass waste streams in Manitoba.
Landfill gas is produced by the decomposition of organic material by anaerobic (in the absence of oxygen) digestion at landfill disposal sites. It is the most common bio-gas power application.
Landfill sites generate a substantial amount of methane (approximately 50 per cent) and carbon dioxide (approximately 50 per cent), with trace amounts of other chemical constituents. In Canada alone, the methane from landfill operations contributes to approximately 1.2 million tonnes of greenhouse gases released into the atmosphere each year.
This gas can be captured and utilized, thereby significantly reducing greenhouse gases and nuisance odours. The captured methane can be used in an internal combustion engine (most commonly used), gas turbine or steam turbine to generate electricity or can be directly piped to an off-site location for combustion.
Economics of landfill gas
The total installed landfill gas cost (including generation, gas clean-up and emissions control), is approximately $2,000/kW (2007 CDN$) and is expected to decrease slightly over the next 8 to 10 years.
Landfill gas project
We are presently working with the City of Winnipeg on a project to capture and manage landfill gas at the Brady Landfill site. We are studying the options for using this landfill gas.
Gasifiers are devices used to convert a solid fuel such as biomass, to a combustible gaseous fuel through a thermochemical process, under carefully regulated temperature, pressure and atmospheric conditions (using less air or oxygen). The resulting product is a fuel gas or biogas, which, like natural gas, can be burned in a gas turbine.
Biogas can also be used in a boiler to produce steam for electricity generation and can be burned directly for space heating or drying.
There are 4 main types of gasifiers: updraft, downdraft, fluidized-bed and entrained flow. Each of these is configured to operate under different conditions (temperature, pressure, flow direction, fuel mix, etc.).
The gasification process
The gasification process includes 3 main stages: pyrolysis, combustion and gasification.
- During pyrolysis, the fuel is heated, volatile constituents are released and a char residue is formed. The resulting quantity and composition of the char is dependent on the fuel type being burned.
- The combustion process occurs as the volatile compounds and a portion of the char residue reacts with oxygen to form carbon dioxide and carbon monoxide. These 2 gases provide heat for the subsequent gasification process.
- The gasification process occurs as the char residue reacts with carbon dioxide and steam to produce carbon monoxide and hydrogen.
Ethanol fuel is made from corn, barley, and wheat, as well as high-cellulose biomass such as trees and grasses. Ethanol is most commonly used to increase octane and improve the emissions quality of gasoline when blended, but can also be burnt directly as a fuel.
Manitoba has passed biofuels legislation to mandate the use of 10 per cent ethanol (E10) in gasoline. This will come into effect when local production can support the demand.
Higher blends of ethanol require that the vehicle be specifically designed to handle them. Some newer vehicles are designed to use 85 per cent ethanol (E85).
Biodiesel fuel is a form of diesel fuel made from vegetable or rendered animal oils in a process known as transesterification.
Biodiesel is usually blended with petroleum diesel in blends of 2 per cent (B2) or more and does not generally exceed 20 per cent (B20) in our climate, due to the formation of crystals that cause the biodiesel to gel in winter. Blending with biodiesel will reduce dependence on fossil fuel usage.
We are taking a lead in promoting biodiesel and doing our part to reduce emissions of greenhouse gases. Presently, biodiesel blends of B5 (winter) and B20 (summer) are used at Manitoba Hydro refuelling sites in Winnipeg.