CIV 220F ENGINEERING ECOLOGY Practice Problems #4: Urban material and energy flows. Sewers Wastewater Treatment Food Production. Landfill Green Bin

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1 CIV 220F ENGINEERING ECOLOGY Practice Problems #4: Urban material and energy flows Question 1 The flows of mass and energy involved in the nourishment of Toronto households are shown in Table 1 below. Process (TO) Process (FROM) Grocer y Store Kitchen Human Body Landfill Green Bin Sewers Wastewater Treatment Food Production 1121 [5.6] Grocery 1107? Store [5.5] Water Supply 797 [0] Kitchen ? [4.3] [0.3] [0.1] Human? Body Sewers 1268 [1.3] Table 1 Flows of mass (kg/capita top number) and energy (GJ/capita in square brackets) in the nourishment of Toronto households in a) Construct a material flow analysis (MFA) diagram for the nourishment of Toronto households. Your diagram should include all the processes shown in Table 1, and the associated flows of energy and materials. Clearly identify and label the following flows in your diagram: grocery store import retail solid waste food and beverages purchased tap water meals and beverages ingested kitchen solid waste kitchen organic waste kitchen liquid waste human respiration & transpiration (to the atmosphere) faeces & urine sewer discharge 1

2 b) Determine values for the four unknown flows of mass and energy: retail solid waste kitchen liquid waste human respiration & transpiration (to the atmosphere) faeces & urine c) Assuming that the purpose of the nourishment system is to provide for the human body metabolism, what is the overall efficiency of the system with respect to mass and with respect to energy? Efficiency can be interpreted as the ratio of useful output to total input. Question 2 a) What is meant by global warming potential? b) In 2005, Ontario s electricity was generated from a variety of sources. Use the data on these sources from Table 2 to determine the average greenhouse gas (GHG) intensity for Ontario s electricity mix in Source Coal Natural Gas Oil Hydro Nuclear Other Ontario Generation in 2005 (GWh) 27,437 13, ,551 77, GHG Intensity (t CO 2 e /GWh of generation) 1, Table 2 Ontario s Electricity Generation and GHG Intensity for c) In 2005, the Greater Toronto Area (GTA) consumed 55,778 GWh of electricity, and 327,000 TJ of natural gas. The estimated consumption of gasoline and diesel fuels was 6,813 and 2,011 million litres respectively. A further 1,830 million litres of jet fuel was loaded onto planes at Toronto Pearson Airport. Two cement plants in the GTA reported GHG emissions of 2,755,000 tco 2 e to Environment Canada. A Petro-Canada refinery in Mississauga also reported emission of 430,369 tco 2 e. Emissions from waste were 1,811,210 t CO 2 e. Assume that electricity transmission and distribution losses were 12%. If the population of the GTA was 5,555,912 in 2005, what were the direct GHG emissions per capita? (Use data from Table 3 over page to answer this question). 2

3 Energy content (TJ/ML) Direct Emissions t eco 2 /TJ (IPCC) Gasoline (Low Sulphur) Diesel Jet kerosene LPG (Petroleum based) Marine fuel varies Natural Gas (dry) N/A Fuel Oil varies Coal: Anthracite Coking/Bituminous N/A Lifecycle Emissions t eco 2 /TJ (GHGenius) Table 3 Direct and Lifecycle GHG Emissions Intensity Factors for Fuels. d) Explain the difference between the direct and lifecycle GHG emission intensity factors in Table 3, i.e., what additional processes are considered in the lifecycle factors? If the GTA greenhouse gas inventory for 2005 included lifecycle emissions for gasoline, diesel, jet fuel and natural gas, what is the GHG emissions per capita? 3

4 CIV 220 Problem Set #4 Solutions Question 1 The flows of mass and energy involved in the nourishment of Toronto households are shown in Table 1 a) Construct a material flow analysis (MFA) diagram for the nourishment of Toronto households: o Mass and energy flows of goods associated with the activity to nourish Toronto households in The figure on food input includes food consumed outside of the home. Numbers indicate mass (kg/capita/year); energy content presented in square backets (GJ/capita/year). STP denotes sewage treatment plant; GJ denotes Giga Joules, were 1 GJ=10 9 J. Round brackets indicated calculated values from the problem.

5 b) Determine values for the four unknown flows of mass and energy: c) Efficiency: Or Or

6 Question 2 a) What is meant by global warming potential? Global Warming potential expresses the contribution of greenhouse gas in warming the atmosphere relative to CO 2. b) In 2005, Ontario s electricity was generated from a variety of sources. Use the data on these sources from Table 2 to determine the average GHG intensity for Ontario s energy mix for Ontario Electricity Mix Source Generation (GWh) GHG Intensity (t CO2e /GWh) Emission (t CO2e) Coal 27,437 1, ,601,622 Natural Gas 13, ,911,056 Oil ,768 Hydro 34, Nuclear 77, Other OVERALL 155, ,177,446

7 c) What are the direct Per Capita emissions? Consumption (GWh) Line Loss factor Intensity (t CO2e /GWh) Emissions (tco2e) Electricity 55, ,743,699 Consumption (TJ) Intensity (t CO2e /TJ) Natural Gas 327, ,344,700 Consumption (ML) Energy intensity (TJ/ML) Intensity (t CO2e /TJ) Gasoline ,399,681 Diesel ,619,848 Jet fuel 1, ,584,309 Direct Industrial Two cement plants 2,755,000 Petro-Canada Lubricant Centre in Mississauga 430,369 Waste 1,811,210 Total 63,688,817 Population 5,555,912 Per capita 11.46

8 d) Explain the difference between the direct and lifecycle GHG emission intensity factors in Table 3, i.e., what additional processes are considered in the lifecycle factors? If the GTA greenhouse gas inventory for 2005 included lifecycle emissions for gasoline, diesel, jet fuel and natural gas, what is the GHG emissions per capita? The lifecycle GHG intensity factors include upstream processes such as extraction, refining, and transportation of fuels. Consumption (GWh) Line Loss factor Intensity (t CO2e /GWh) Emissions (tco2e) Electricity 55, ,743,699 Consumption (TJ) Intensity (t CO2e /TJ) Natural Gas 327, ,203,300 Consumption (ML) Energy intensity (TJ/ML) Intensity (t CO2e /TJ) Gasoline ,788,792 Diesel ,917,438 Jet fuel 1, ,941,553 Direct Industrial Two cement plants 2,755,000 Petro-Canada Lubricant Centre in Mississauga 0 Waste 1,811,210 Total 75,160,991 Population 5,555,912 Per capita 13.53