Appendices

Appendix 5.4: Calculating reductions in greenhouse gas emissions

Although the following examples may seem specialized, the method used to calculate emissions reductions applies to any energy management project that reduces consumption of fuel or electricity.

On-site combustion systems

Use the data in Table 1 and the information given below to calculate the amount of CO2, CH4 and NOx produced by combustion systems in the following example. To perform this calculation for your own facilities, obtain precise data from your natural gas utility.

  • When the soaking pit in a steel mill was re-insulated, the original natural gas burners were retrofitted with high-efficiency burners. Annual fuel savings are estimated at 50 terajoules (TJ). What would be the corresponding reductions in CO2, CH4 and NOx emissions?
  • The emissions factors for natural gas fuel are CO2: 49.68 t/TJ; CH4: 0.13-1.27 kg/TJ; NOx: 0.62 kg/TJ. A range of 0.13–1.27 kg/TJ has been indicated for CH4, so we will assume 0.6 kg/TJ for this calculation.

    CO2 reduction = 50 TJ/yr. X 49.68 t
    CO2/TJ = 2 484 t/yr.
    CH4 reduction = 50 TJ/yr. X 0.6 kg
    CH4/TJ = 30 kg/yr.
    NOx reduction = 50 TJ/yr. X 0.62 kg
    NO2/TJ = 31 kg/yr.
     
     

TABLE 1:
Greenhouse Gas Emissions Factors by Combustion Source

Fuel type CO2 CH4 NOx
Gaseous fuels t/ML t/TJ kg/GL kg/TJ kg/ML kg/TJ
Natural gas 1.88 49.68 4.8–48 0.13–1.27 0.02 0.62
Still gas 2.07 49.68 – – 0.02 0.62
Coke oven gas 1.60 86.00 – – – –
Liquid fuels t/kL t/TJ kg/kL kg/TJ kg/kL kg/TJ
Motor gasoline 2.36 67.98 0.24–4.20 6,92–121.11 0.23–1.65 6.6–47.6
LPGs 1.11–
1.76		 59.84–
61.38		 0.03 1.18 0.23 9.00–12.50
Diesel oil 2.73 70.69 0.06–0.25 1.32–5.7 0.13–0.40 3.36–10.34
Light oil 2.83 73.11 0.01–0.21 0.16–5.53 0.13–0.40 3.36–10.34
Heavy oil 3.09 74.00 0.03–0.12 0.72–2.88 0.13–0.40 3.11–9.59
Petroleum coke 4.24 100.10 0.02 0.38 – –
Solid fuels t/t t/TJ g/kg kg/TJ g/kg kg/TJ
Anthracite 2.39 86.20 0.02 varies 0.1–2.11 varies
U.S. bituminous 2.46–
2.50		 81.6–
85.9		 0.02 varies 0.1–2.11 varies
Canadian bituminous 1.70–
2.52		 94.3–
83.0		 0,02 varies 0.1–2.11 varies
Sub-bituminous 1.74 94.30 0.02 varies 0.1–2.11 varies
Lignite 1.34–
1.52		 93.8–
95.0		 0.02 varies 0.1–2.11 varies
Coke 2.48 86.00 – – – –
Fuel wood 1.47 81.47 0.15–0.5 0.01–0.03 0.16 8.89

Abbreviations: t: tonne; kg: kilogram; g: gram; ML: megalitre; TJ: terajoule; kL: kilolitre; GL: gigalitre. (See Appendix 5.1: Energy units and conversion factors.)

Source: Voluntary Challenge and Registry Program Participant's Handbook, August 1995, and its addendum issued in March 1996. Data supplied by Environment Canada.

Impact of reductions in electrical consumption

Energy management projects that reduce electrical consumption also have a positive effect on the environment. However, the emissions reductions occur at the electrical generating station rather than at the site of the efficiency improvements. To calculate the emissions reduction, use the method outlined above, and then calculate the energy saved at the generating station. This is done by adjusting the figure representing energy saved at the site to account for losses in the electrical distribution system.

Using Table 1 and the information given below, calculate emissions reductions. To perform this calculation for your own facilities, obtain precise data from your electrical utility.

  • At a large manufacturing plant in Saskatchewan, the energy management program involved replacing fluorescent light fixtures with metal halide fixtures and replacing several large electric motors with high-efficiency motors. The total annual energy saving was 33 600 MWh. Calculate the corresponding reduction in emissions.
  • Table 2 shows that, in Saskatchewan, the average CO2 emissions from electrical power generation is 0.83 t/MWh.
  • Convert to equivalent energy saving at the generating station using a transmission efficiency of 96%.
Annual energy savings at generating station = 33 600 MWh / 0.96
= 35 000 MWh
CO2 reduction = 35 000 MWh/yr. X 0.83 t/MWh
= 29 050 t/yr.

TABLE 2:
Average CO2 Emissions for 1998, by Unit of Electricity Produced

  t/MWh t/TJ
Atlantic provinces 0.25 68.4
Quebec 0.01 2.5
Ontario 0.23 65.2
Manitoba 0.03 8.2
Saskatchewan 0.83 231.7
Alberta 0.88 245.3
British Columbia 0.03 7.5
Northwest and Yukon Territories 0.40 109.8
Canada average 0.22 61.1

Source: Demand, Policy and Analysis Division, Office of Energy Efficiency, Natural Resources Canada.

 

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