Hey there, time traveller!
This article was published 3/10/2017 (1473 days ago), so information in it may no longer be current.
Household garbage is a low-hanging fruit in the area of utilizing waste biomass for energy. Let’s take a closer look at this potential resource.
We all realize that a good portion of our home utility bills go towards heating. So even if all of our transportation and power needs were met by renewable electricity, we would still be using imported natural gas for things such as space heating and cooking. In Manitoba, 32 per cent of all of the energy used provincially comes from natural gas.
The recent provincial ban on coal has resulted in the establishment of a biomass fuel market of about 50,000 tonnes/year, most of which is consumed by industrial users (greenhouses, workshops, warehouses, manufacturing facilities, etc.) in the form of solid fuel pellets mainly originating from waste wood or agricultural residue.
This still represents a very small portion of the overall heating fuel needs, but with the incoming federal carbon tax in 2018 and growing awareness of renewable energy, expansion of biomass fuels can be expected.
One of the main challenges of biomass energy is distance between sources and users of the fuel. According to the 2016 census, 71 per cent of Manitobans live in urban centres, while most waste biomass sources originate from rural areas as a result of forestry, farming and agricultural processing. There is one exception, which presents a yet-unrealized opportunity for Manitoba: urban waste from households, businesses, and institutions.
A significant opportunity in this area is landfill gas (LFG), also referred to as landfill biogas or renewable natural gas. LFG is generated naturally within mature landfills as a result of the biodegradation of organic material, resulting in a gaseous emission of about 50 per cent methane, with carbon dioxide and some trace gases (such as hydrogen sulfide and volatile hydrocarbons) making up the rest. This gas is classified as a medium-BTU heating source (about half as potent as natural gas) and can be collected and used for a variety of heating, electricity, or transportation fuel applications.
In 2013, the City of Winnipeg started collecting landfill biogas at its Brady Road Resource Management Facility (previously the Brady Road Landfill) and is now in the process of doubling the volume of collection to 2,000 cubic feet a minute (cfm). The collected gas is flared to convert the methane in the biogas to carbon dioxide, thereby reducing greenhouse gas (GHG) potency of the emissions by about 95 per cent.
A secondary benefit of biogas collection and combustion is odour mitigation from the otherwise freely released gases, as well as destruction of some volatile organic compounds that may pose concerns to nearby populations. Although fairly late to the game (as many large urban landfills in Canada have biogas collection, with some utilizing the gas for a variety of applications), this initiative has had a substantial impact on greenhouse gas emissions, equal to getting 21,700 cars off the road. With the doubling of gas collection in the coming year, it can be expected these GHG savings would double as well.
According to a 2013 report by the Canadian Biogas Association, of the 68 Canadian landfills that capture LFG, 53 per cent convert it to usable energy in the form of heat or electricity. Judging from the recent reports from across the country (including Regina and Saskatoon), this number has been growing.
In the United States, the EPA reports that there are currently 634 LFG-to-energy projects. Three-quarters of these projects involve the generation of electricity (through the use of combustion engines or a variety of turbines), 20 per cent use the gas directly for heating applications (for nearby buildings, greenhouses, kilns, and industrial or institutional boilers) and six per cent upgrade the LFG to high-BTU gas that can be added to natural gas pipelines or compressed and used for fuelling a fleet of trucks.
The choice of the conversion technology is strongly related to the size and age of the landfill, the distance to a nearby user of the gas and local economics (electricity prices, natural gas costs, state incentives, utility targets, etc.).
So how much energy is available from a landfill such as the Brady Road facility? The projected 2,000 cfm of LFG to be collected from the landfill is equal to the heating needs of approximately 6,000 homes in Manitoba. The most cost-effective means of bringing this energy to market is through direct use in a heating application such as a large boiler or furnace.
District heating systems with a central power plant or a large industrial user of heat are ideal for LFG applications. Most existing LFG energy systems have users that are within 16 kilometres of the landfill. One potential LFG user, in the case of the Brady Road facility, could be the power plant at the University of Manitoba Fort Garry campus, which has six large natural gas boilers supplying power to a host of buildings. With minor modifications, the LFG could replace the natural gas used at one of these boilers, with potential for future expansion. If another large consumer could be found at a closer proximity, the economics would further improve.
Higher-value applications, such as upgrading the LFG to natural gas, producing electricity, or displacing diesel with compressed LFG as a transportation fuel are well established in other jurisdictions, but come with greater upfront cost. The payback on these projects might be a bit longer, but the economics are quickly changing, due to improvements in technology, carbon pricing and environmental legislation.
One of my favourite sayings is that "waste is resource out of place." It’s time to take another look at our landfills.
Nazim Cicek is a professor and associate head of the department of biosystems engineering at the University of Manitoba.