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The above table shows that the Process Implementation stage, which involves the construction of the landfill and power-generating facility, has the most adverse effect on the environment. The primary materials used in the construction of these facilities are concrete, steel, clay, geosynthetics and sand<ref>Univeristy of Maryland University College, “Landfill Construction Simulation,” University of Maryland University College. [Online]. Available: http://www.umuc.edu/ade/bp/envm/02-constr/constr.html. [Accessed: Mar. 1, 2009]</ref>. While none of these materials are toxic, steel production makes use of virgin iron ore as well as energy-intensive furnaces in many of stages<ref>General Motors, “Greenhouse Gas Emissions from Trucks and Cars,” General Motors. [Online]. Available: http://www.gm.com/corporate/responsibility/reports/00/vision/environment/product.html. [Accessed: Feb.26, 2009].</ref>. While the process implementation phase of using LFG to generate power can be seen to be energy-intensive, no other feasible alternatives are present. |
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Revision as of 06:39, 8 April 2009
This page is part of the Design for the Environment course
The accumulation of solid waste is a serious issue as cities continue to grow. Toronto is one such city that has been challenged by this issue. When Toronto closed the Keele Valley Landfill, waste was diverted to a dump in Michigan. Between January and August 2007, approximately 441,363 tonnes of solid waste (which could fill 74 trucks) was sent to the Michigan landfill daily[1]. However, the Michigan dump has given the Toronto Solid Waste Management until 2010 to reroute their garbage to another location[2]. As a result, several options of how to deal with Toronto's trash must be assessed for the client, the Toronto Solid Waste Management. This article focuses on the broad option of converting garbage to energy as it deals with the issue of solid waste accumulation and provides an additional energy source. The option is divided into three alternatives, a baseline alternative which is using gas generated from landfills and two newer alternatives which are incineration and gasification. Two of these alternatives are currently in place in Toronto. The city recently opened the Green Lane Landfill which could be an adequate source of landfill gas. In addition, the City of Brampton, near Toronto, has an incineration facility [3]. There is no gasification facility in Toronto; the nearest facility is located in Ottawa[4]. Each alternative will be compared based on their functional, environmental, cost and social impacts. When using landfill gas, as methane escapes through decomposing garbage, it is collected in pipes situated on the landfill site. The methane is combusted to release energy. The incineration alternative involves burning garbage directly to generate energy within an enclosed facility. In the final option, gasification, garbage is gasified into a gas called syngas. The syngas is combusted to release energy.
Project Information
MIE315, Section 2, Group B15
Khalil Heileman [Heileman]
Micael Tecle [teclemic]
Animesh Roy [Royanimesh]
Sara Makaremi [Makaremi]
Highlights and Recommendations
In terms of environmental impacts, gasification is the best alternative for dealing with Toronto's solid waste. The gasification alternative has the strongest results in the EIOLCA and the second highest score in the SLCA. However, it should be noted that the SLCA is a subjective analysis and the EIOLCA is based on many assumptions. Gasification also does not have the social controversies surrounding it, unlike incineration. The main concern in gasification is the the technology is relatively new. As a result, not a lot of available experience in handling gasification facilities. In addition, gasification is an expensive process and this cost will be carried on to taxpayers.
| SLCA score | GWP (MTCO2) | Conventional Air Pollutants (metric tons) | Energy Use (Terajoules) | Toxic Air Releases (kg) | |
|---|---|---|---|---|---|
| Landfill Gas | 71 | 3015.71 | 79,730 | 716.7 | 5,941 |
| Incineration | 74 | 135.33 | 85,409.6 | 304.5 | 1,928 |
| Gasification | 72 | 564.55 | 12,990 | 131.7 | 1,967 |
Functional Analysis
The main function of each alternative is to convert garbage into energy. As each alternative uses different kinds of garbage, for the sake of a simple comparison, only plastics and organics as input garbage will be considered. Organic garbage releases energy in all of the alternatives. Although plastics yield little energy in landfill gas, they are critical for energy yield in incineration and gasification. As a result, the impact of plastics cannot be overlooked. Since all of the alternatives should receive their garbage stream from the city of Toronto, the impacts of collecting garbage will be ignored. Each of the processes are broken down into five life stages: resource provisioning, process implementation, primary process operation, secondary process operation and end of life.
Baseline Alternative: Landfill Gas to Energy
Landfill gas (LFG) is produced upon the anaerobic decomposition of waste buried in the landfill. This process is carried out by anaerobic microorganisms[5]. This gas is primarily composed of methane (CH4) and carbon dioxide (CO2), with trace amounts of other components such as oxygen compounds, sulphur compounds and hydrocarbons[6]. The produced LFG is collected and extracted from vertical gas wells located in the landfill, treated, and subsequently used to generate electricity[7][8]. The utilization of LFG to generate electricity usually involves the use of either internal combustion engines or steam turbines[9]. The primary advantage of using LFG to generate power lies in the fact that the process makes optimal use of the inevitable presence of landfills. Furthermore, the presence a gas collection system reduces the amount of gas seeping through the landfill and escaping into the atmosphere.
Alternative 1: Incineration
A more recent alternative is using an incinerator where garbage is burned directly to extract energy. The advantage of incineration is that energy can be yielded along with large reductions in garbage volume. However, the disadvantages include output of ashes and toxic chemicals [10]. Bottom and fly ashes, toxic metals, acid gases and dioxins are some of the by products of incineration [11]. These are highly toxic pollutants, especially dioxin which could cause serious health problems such as cancer, neurological damage, thyroid damage, respiratory issues [12].
Alternative 2: Gasification
In the final alternative which is the gasification process, carbon-based waste are heated at high temperature (700ºC) and pressure[13]. CO and H2 are removed from the complex blend of gas resulted from the process to produce a fuel gas, called Syngas. To avoid oxidation, this endothermic process is implemented in an oxygen-limited chamber[14].The process yields three by-products: 1-accumulation of inert solid slag from non-volatile waste which is vitrified to be used in road pavements and asphalt. 2-sulphur that can be added to soil, 3- heavy metals such as mercury that should be disposed safely in landfill. According to PlascoEnergy of Ottawa, One tonne of garbage results in 150 Kg of slag, 5Kg of sulphur and 1.3Kg of heavy metals[15]. It should be noted that chlorine-rich plastics such as PVC cannot be gasified due to their sever emissions [16]. They can be gasified only if the chlorine content is removed. The contaminants emerging from gasification depend on the quality of the equipment and the processing temperature. Oil refining industry uses the hydrogen from Syngas to purify fuels and to enhance heavy crude oil. Conventionally, natural gas was used to provide the required hydrogen. However, the cost of natural gas has been increasing. Therefore, the new technology helps refiners to convert low-value feedstock to valuable hydrogen and to generate power needed for refining infrastructure at the same time.
Streamlined Life Cycle Assessment (SLCA)
SLCA is a semi-quantitative approach for life cycle assessment of alternatives. It comprises a matrix of 5×5 where each alternative is given a score between 0 (most adverse environmental impact) to 4 (least environmental impact). The total score for each life stage and environmental impact is obtained by adding the corresponding scores in each row and column. The columns are divided into five life stages, that is process implementation, resource provisioning, primary process operation, secondary process operation and end of life. The rows are divided into process inputs (material and energy) and process outputs (gaseous, liquid, solid). The following matrices are created for the SLCA comparison:
Landfill Gas SLCA Chart
| Material Choice | Energy Use | Gaseous Residues | Liquid Residues | Solid Residues | Total | |
|---|---|---|---|---|---|---|
| Resource Provisioning | 4 | 3 | 3 | 4 | 4 | 18 |
| Process Implementation | 2 | 2 | 1 | 3 | 2 | 10 |
| Primary Process | 4 | 4 | 2 | 4 | 1 | 15 |
| Secondary Process | 3 | 4 | 4 | 4 | 1 | 16 |
| End of Life | 2 | 3 | 2 | 3 | 3 | 13 |
| Total | 15 | 16 | 11 | 17 | 11 | 72 |
The above table shows that the Process Implementation stage, which involves the construction of the landfill and power-generating facility, has the most adverse effect on the environment. The primary materials used in the construction of these facilities are concrete, steel, clay, geosynthetics and sand[17]. While none of these materials are toxic, steel production makes use of virgin iron ore as well as energy-intensive furnaces in many of stages[18]. While the process implementation phase of using LFG to generate power can be seen to be energy-intensive, no other feasible alternatives are present.
Incineration SLCA Chart
| Material Choice | Energy Use | Gaseous Residues | Liquid Residues | Solid Residues | Total | |
|---|---|---|---|---|---|---|
| Resource Provisioning | 4 | 3 | 3 | 4 | 4 | 18 |
| Process Implementation | 2 | 2 | 2 | 3 | 3 | 12 |
| Primary Process | 3 | 4 | 2 | 4 | 2 | 15 |
| Secondary Process | 4 | 4 | 4 | 3 | 3 | 16 |
| End of Life | 2 | 2 | 3 | 3 | 3 | 13 |
| Total | 15 | 15 | 14 | 17 | 15 | 74 |
Gasification SLCA Chart
| Material Choice | Energy Use | Gaseous Residues | Liquid Residues | Solid Residues | Total | |
|---|---|---|---|---|---|---|
| Resource Provisioning | 4 | 3 | 3 | 4 | 4 | 18 |
| Process Implementation | 2 | 2 | 2 | 3 | 3 | 12 |
| Primary Process | 2 | 3 | 2 | 4 | 3 | 14 |
| Secondary Process | 4 | 4 | 4 | 3 | 3 | 18 |
| End of Life | 2 | 2 | 3 | 3 | 3 | 13 |
| Total | 14 | 14 | 14 | 17 | 16 | 75 |
From the above table it can be predicted that resource provisioning and secondary process (cleaning and filtering) are the life stages with the least environmental impact. This is mainly due to the fact that the material input to the process is invaluable waste and the environmental impacts mainly result from collection and haulage activities. In contrast, building the infrastructure for the process requires construction materials such as steel and cement. Steel production from virgin ore is energy intensive-furnaces[19], while production of one tonne of cement releases one tonne of CO2[20]. Also, the mechanical devices such as turbines and torches in the facility are manufactured from metal alloys. Therefore, the process implementation requires a higher material and energy input compared to the other life stages.
Cost Analysis
The cost analysis presents a method to compare the costs of each alternative at different life stages. The analysis also provides economic information that can be input into the EIOLCA model software available at http://www.eiolca.net/. The EIOLCA will be discussed in the following section. Some of the dollar values in the cost analysis are converted to their $1997 equivalent using the inflation calculator[21].
Landfill Gas Cost Analysis
| Capital Costs ($US) | |
| Process Implementation | |
| Constructing Landfill | $10,008,068 |
| Construction of power generation facility | $2,049,219 |
| Closure of Landfill | $52,770,000 |
| Total | $64,827,287 |
| Annual Costs ($US) | |
| Resource Provisioning | |
| Garbage Transfer | $21,691,219 |
| Process Implementation | |
| Landfill O&M | $1,407,109/year |
| Primary and Secondary Process | |
| Power generation facility O&M | $4,144,791/year |
| Landfill post-closure O&M | $61,000/year |
| Total | $27,304,119/year |
Incineration Cost Analysis
| Capital Cost Items Total Value | US($1997) |
| Site Development | $233,798.12 |
| Buildings | $490,661.53 |
| Processing Equipment | $86,232.72 |
| Ash Storage | $72,406.65 |
| Power Block Equipment | $2,776,156.11 |
| Contingency | $731,864.13 |
| Engineering/Cont observations | $351,286.92 |
| Permitting | $26,341.60 |
| Surveying and soils report | (est) $2,195.13 |
| Construction Management | $175,643.46 |
| Incremental cost for extraction of Turbine | $83,873.77 |
| Heat Exchanger and Onsite Piping | $40,265.96 |
| Piping to Customers | $21,296.07 |
| Full EU compatibility | $50,324.26 |
| Dioxin Sampling | $5,897.37 |
| Contingency Odour Control Enhancement | $67,099.01 |
| Allowance for Enhanced Architectural features | $294,868.71 |
| Viewing Gallery | $33,549.51 |
| Education Centre | $16,774.75 |
| Contingency for Site Improvements | $334,184.53 |
| Differential Cost for System Redundancy | $579,875.69 |
| Total Estimate | $6,474,596.00 |
| Operating and Maintenance Cost Items | Total Value US ($1997) |
| Labour | $1,927,130.81 |
| Annual Maintenance and Repairs | $1,414,714.53 |
| Major Repair and Replacement Cost | $652,642.74 |
| Utilities and Reagents | $1,021,556.25 |
| Rolling Stock O&M Cost | $73,389.54 |
| Miscellaneous Cost | $515,692.60 |
| Property Tax to Clarington | $634,295.35 |
| Process Residual Haul and Disposal | $2,794,044.81 |
| Profit and Contingency | $1,115,258.97 |
| Incremental cost for extraction of turbine | $60,284.27 |
| Heat Exchanger and Onsite Piping | $7,207.90 |
| Piping to Customers | $8,518.43 |
| Full EU compatibility | $309,284.51 |
| Dioxin Sampling | $53,076.37 |
| Contingency Odour Control Enhancement | $21,623.71 |
| Allowance for Enhanced Architectural features | $122,534.33 |
| Viewing Gallery | $81,907.97 |
| Education Centre | $8,518.43 |
| Differential Cost for System Redundancy | $262,105.52 |
| Total Estimate | $11,083,787.04 |
Following table summarizes the cost analysis of a 56 MW integrated biomass gasification combined cycle power plant[22].
Gasification Cost Analysis
| Resource Provisioning | US($2008) |
| Waste Haulage | $26.88/tonne |
| Process Implementation (Capital Cost) | US($1997) |
| Buildings | 10,227,014.76 |
| General Plant Facilities | $6,000,189.56 |
| Working Capital | $2,022,903.52 |
| Engineering Fees | $8,999,772.99 |
| Steam Cycle | $3,204,123.72 |
| Gas Turbine | $13,459,774.12 |
| Air boost compressor | $603,393.87 |
| Char combustor | $1,242,582.29 |
| Quench System | $15,340.52 |
| Startup Costs | $2,301,078.32 |
| Total | $53,165,136.21 |
| Primary Process (Gasification) | US($1997) |
| Gasification | $21,448,095.35 |
| Electricity | $62,384,790.01 |
| Total | $83,832,885.36 |
| Secondary Process(Cleaning and Filtering) | US($1997) |
| Particulate Cleanup | $2,761,293.98 |
| Bottom Ash Removal | $10,738,365.4 |
| Fly Ash Removal | $42,953,461.98 |
| Disposal Costs | $10,390,442.45 |
| Total | $66,843,563.90 |
The above values are obtained by assuming that 140,000 tonnes of garbage is processed by gasification annually[23]. For the resource provisioning stage, it should be noted that waste transportation cost strongly depends on the location of the plant. If the plant is far from the municipal waste management, where the garbage is collected, it will require more energy to transport the garbage. From above values it can be concluded that the primary process has the highest cost among other life stages. The complexity of gasification process that requires the integrity of several operating processes and the cost of electricity to run electric heaters,turbines, steam cycles,etc result in its high operating cost. Moreover, depending on the input waste to the system, some mechanical pre-processing of the feedstock is required after the recyclable materials and metals and inerts are removed. Coarse shredding, fine shredding, sorting and elaborate front-end processing are a few examples[24].This complexity requires high capital investment. As a consequence, its application was previously focused only on destroying hazardous waste[25].
Economic Input Output Life Cylce Assessment (EIOLCA)
The EIOLCA is used to obtain quantitative information about environmental impacts of the process life stages. The United States Department of Commerce has divided the American economy into hundreds of economic sectors. Of these sectors, the ones that have inputs in the different life stages of each alternative process are analyzed. These inputs are measured in dollars and the dollar values are input into a software available at http://www.eiolca.net/. Since the software is based on information available in 1997, all dollar values must be converted to 1997 dollars. The software then outputs values of the input sector contribution to the environmental impacts. The impacts highlighted in this comparison are global warming potential (GWP) measured in metric tons of CO2 equivalents and conventional pollutants (CO, NOx, SO2, VOC and PM10) in metric tons.
Landfill Gas
Incineration
In the incineration alternative, the EIOLCA shows that the life stage that has the largest impact on global warming is the primary process operation. This stage accounts for 64% of all GWP emissions. As this process involves combustion of garbage, a high amount of GWP emissions is not surprising. However it should be noted that in the secondary process operation, a lot of the pollutants from the primary process are filtered out and cleaned. The stage with the least impact is the process implementation stage which accounts for only 5% of GWP emissions. This stage involves the construction of the facilty, which takes up a small amount of time in the total life cycle. As a result, the small amount of GWP emissions is expected. The EIOLCA also revealed that the entire incineration process yields 85,409.6 MTCO2E, which is the largest amount of GWP pollutants for all alternatives. The EIOLCA also shows that throughout the life cycle of incineration, the air pollutant with the most emissions is carbon monoxide. This pollutant is emitted mostly in the primary process and resouce provisioning stages. Of all the alternatives, incineration is the process with the second highest amount of carbon monoxide emissions, after the landfill gas process.
Gasification
For the gasification process, the GWP chart obtained from EIO-LCA reveals that the contribution of resource provisioning to the global warming is 50%. This could be predicted from the fact that waste haulage is the main activity in resource provisioning stage. At this stage truck transportation contributes to high CO emissions; as it is depicted in the conventional pollutants graph. High emissions of CO can lead to global warming. In contrast to resource provisioning, process implementation and primary process have negligible conventional pollutant emissions.
Societal Analysis
Baseline: Landfill Gas
A portion of society has concerns about noise, odours and low aesthetic appeal of landfills[26].
Alternative 1: Incineration
There has been strong public opposition for the incineration facility proposed for Durnham region near Toronto due to its highly contaminating process[27].
Alternative 2: Gasification
Gasification also leads to societal concerns for the litter, dust and noise that mostly result from the haulage activities [28].
Notes
- ↑ City of Toronto, “Facts about Toronto’s Trash”, November 1st 2007. [Online], Available: http://www.toronto.ca/garbage/facts.htm. [Accessed: March 1st, 2009]
- ↑ City of Toronto, “Facts about Toronto’s Trash”, November 1st 2007. [Online], Available: http://www.toronto.ca/garbage/facts.htm. [Accessed: March 1st, 2009]
- ↑ Canada. City of Brampton. “Incineration and Waste Processing Transfer and Disposal Study”. [Online Document] Available: http://www.brampton.ca/city_dept/pdd/specialprograms/ WasteProcessingPresentation.pdf [Accessed: March 11th 2009]
- ↑ Impact Lab (2008), "Ottawa To Build The First Gasification Plant In North America" [Online]. Available: http://www.impactlab.com/2008/07/06/ottawa-to-build-the-firstgasification- plant-in-north-america/
- ↑ Canada. City of Toronto. City of Toronto Long Term Residual Waste Management Study. Toronto, ON 2007. [E-Book]
- ↑ T. Christensen, R. Cossu, R. Stegmann, Landfilling of Waste: Biogas, Bury St Edmunds, Suffolk: St Edmundsbury Press Ltd, 1996, pp. 51-55.
- ↑ Environment Canada, “Niagara Waste Systems- Landfill Gas to Energy,” Environment Canada, [Online] Available: http://www.ec.gc.ca/nopp/lfg/en/issue19.cfm. [Accessed Feb. 16, 2009]
- ↑ T. Christensen, R. Cossu, R. Stegmann, Landfilling of Waste: Biogas, Bury St Edmunds, Suffolk: St Edmundsbury Press Ltd, 1996, p. 13.
- ↑ T. Christensen, R. Cossu, R. Stegmann, Landfilling of Waste: Biogas, Bury St Edmunds, Suffolk: St Edmundsbury Press Ltd, 1996, p. 600
- ↑ Z. Salman, “negative Impacts of Incineration based waste-to-energy technology”, [Online Document] Sept 26, 2008, Available at: http://www.alternative-energynews. info/negative-impacts-waste-to-energy / [Accessed: Jan 28 2008]
- ↑ N.A. “Solid Waste Management” United Nations Environmental Programme, vol 1, pg 253-258, 2005. [online], Available at: http://www.unep.or.jp/Ietc/Publications/spc/Solid_Waste_Management/index.asp. [Accessed: January 20, 2008]
- ↑ N.A. “Solid Waste Management” United Nations Environmental Programme, vol 1, pg 253-258, 2005. [online], Available at: http://www.unep.or.jp/Ietc/Publications/spc/Solid_Waste_Management/index.asp. [Accessed: January 20, 2008]
- ↑ Impact Lab (2008), "Ottawa To Build The First Gasification Plant In North America" [Online], Available: http://www.impactlab.com/2008/07/06/ottawa-to-build-the-firstgasification- plant-in-north-america/
- ↑ Impact Lab(2008),"Ottawa To Build The First Gasification Plant In North America"[Online],Available: http://www.impactlab.com/2008/07/06/ottawa-to-build-the-firstgasification-plant-in-north-america/
- ↑ Impact Lab (2008), "Ottawa To Build The First Gasification Plant In North America" [Online]. Available: http://www.impactlab.com/2008/07/06/ottawa-to-build-the-firstgasification- plant-in-north-america/
- ↑ ] Matti Nieminen, Projects/abstracts "Gasification of Plastic Waste" [Online]. Available: http://virtual.vtt.fi/virtual/waste/abst15.htm
- ↑ Univeristy of Maryland University College, “Landfill Construction Simulation,” University of Maryland University College. [Online]. Available: http://www.umuc.edu/ade/bp/envm/02-constr/constr.html. [Accessed: Mar. 1, 2009]
- ↑ General Motors, “Greenhouse Gas Emissions from Trucks and Cars,” General Motors. [Online]. Available: http://www.gm.com/corporate/responsibility/reports/00/vision/environment/product.html. [Accessed: Feb.26, 2009].
- ↑ General Motors, “Greenhouse Gas Emissions from Trucks and Cars,” General Motors. [Online]. Available: http://www.gm.com/corporate/responsibility/reports/00/vision/environment/product.html. [Accessed: Feb.26, 2009].
- ↑ Ecosmart TM Concrete, “Enviromental Impact Cement Production and the CO2 impact”, [online], Available: http://www.ecosmartconcrete.com/enviro_cement.cfm. [Accessed: March 19th 2009]
- ↑ Bank of Canada, “Inflation Calculator,” Bank of Canada. [Online]. Available: http://www.bankofcanada.ca/en/rates/inflation_calc.html. [Accessed: Mar. 15, 2009]
- ↑ K.R. Craig, M. K. Mann, “Cost and Performance Analysis of Biomass-Based Integrated Gasfication Combines Cycle (BIGCC) Power Systems” October 2006 Available: http://www.nrel.gov/docs/legosti/fy97/21657.pdf [Accessed: February 22nd 2009]
- ↑ Canada. City of Toronto. City of Toronto Long Term Residual Waste Management Study, 2007
- ↑ Canada. City of Toronto. City of Toronto Long Term Residual Waste Management Study, 2007
- ↑ ] Impact Lab (2008), "Ottawa To Build The First Gasification Plant In North America" [Online]. Available: http://www.impactlab.com/2008/07/06/ottawa-to-build-the-first-gasification-plant-in-north-america/
- ↑ A. Bagchi, Design, Construction, and Monitoring of Sanitary Landfill, United States: Wiley, 1990
- ↑ . CBCNews.ca“Durham council approves plan for garbage”,January 24th 2008.[Online], Available: http://www.cbc.ca/canada/toronto/story/2008/01/24/durham-incinerator.html[Accessed March 2nd 2009]
- ↑ Canada. City of Toronto. City of Toronto Long Term Residual Waste Management Study, 2007