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LIFE CYCLE ASSESSMENT REPORT
LifeCycle Assessment Lab Report
CourseName
Lab1
Question1: Environmental Concerns associated with Electricity Generation
The release of Mercury (Hg) into the environment is an environmentalconcern particularly in the coalfired generation of electricity.Coal and other fossil fuels contain Mercury and when the fuel isheated, Hg is released into the air and later settles in waterbodies, affecting the water quality.
The radioactive effluents released from electricitygeneratingnuclear power plants are a major environmental concern. The ionizingradiation is both harmful to human and plant life. The toxic wastescan leach into the environment and into the soil therebycontaminating surface and ground water.
The manufacture and disposal of solar cells used in the generation ofelectricity is an environmental concern. The processes usuallyinvolve generation of hazardous wastes such as Arsenic, whichcontaminate the soil, surface, and groundwater (Larson, 2013).
Question2: Primary Energy Sources used to Generate Electricity in Nova Scotia
These energysources include:

Coal

Natural gas

Wind

Oil

Hydro, solar, and biomass. (Fulton, Mellquist, Kitasei, & Bluestein, 2011)
Question 3: Process Flow Chart
Figure1: Processes involved in coalfired generation of electricity
Question 4:Greenhouse Gases to be considered
Sulfur dioxideand nitrous oxide are the other greenhouse gases that need to beconsidered and included in a more comprehensive life cycle inventory.These gases contribute significantly to the formation of acidic rainthat has adverse effects on the environment.
Question5: Calculation of Fossil Emissions in the Life Cycle Processes
To calculatefossil emissions at bituminous coal mine site associated with amountof coal required to generate 1kWh of electricity, 4.42E01kg ofbituminous coal is required as an input. Also, for every 1.00E+00kgof bituminous coal mined, there are 3.99E03kg of fossil methaneemitted. Therefore, the amount of fossil methane emitted into theatmosphere during the generation of 1kWh of electricity is calculatedas follows:
To calculatefossil emissions for dieselpowered barge transport associated withamount of coal required to generate 1kWh of electricity, 5.59E02tkmof barge transport is used. Also, for every 1.00E+00tkm of bargetransport, there are 6.49E07kg of fossil methane emitted and2.81E02kg of carbon dioxide emitted.
Therefore, theamount of fossil methane emitted into the atmosphere during thegeneration of 1kWh of electricity is calculated as follows:
Amount ofcarbon dioxide emitted is calculated as follows:
To calculatefossil emissions for dieselpowered combination truck associated withamount of coal required to generate 1kWh of electricity, 2.99E02tkmof barge transport is used. Also, for every 1.00E+00tkm of bargetransport, there are 1.29E06kg of fossil methane emitted and7.99E02kg of carbon dioxide emitted.
Therefore, theamount of fossil methane emitted into the atmosphere during thegeneration of 1kWh of electricity is calculated as follows:
Amount ofcarbon dioxide emitted is calculated as follows:
To calculatefossil emissions for dieselpowered train transport associated withamount of coal required to generate 1kWh of electricity, 4.61E01tkmof barge transport is used. Also, for every 1.00E+00tkm of bargetransport, there are 9.05E07kg of fossil methane emitted and1.89E02kg of carbon dioxide emitted.
Therefore, theamount of fossil methane emitted into the atmosphere during thegeneration of 1kWh of electricity is calculated as follows:
Amount ofcarbon dioxide emitted is calculated as follows:
Togenerate 1.00E+00kg of bituminous coal, 1.62E04m^{3}of natural gas is combusted in an industrial boiler. Also, to produce1kWh of electricity, 4.42E01kg of bituminous coal is combusted.Therefore, the amount of natural gas needed to generated 1kWh ofelectricity can be determined as follows:
1.00E+00m^{3}of natural gas combusted in industrial boiler produces 1.96E+00kg ofcarbon dioxide emissions and 3.60E05 methane emissions. Theemissions associated with combusting 7.1604E06m^{3}of natural gas to produce 1kW of electricity can be determined asfollows:
To generate1kWh of electricity, 4.42E01kg of coal is burned. Burning 1.00E+00kgof coal in an industrial boiler leads to the emission of 2.63E+00kgof carbon dioxide and1.15E04kg of methane. Therefore, the amount ofcarbon dioxide emissions released during the generation of 1kWh ofelectricity after burning coal can be calculated as follows:
Amount ofmethane emitted is calculated as follows:
To generate1kWh of electricity, 5.59E02tkm of dieselpowered barge transport isneeded. Also, 1.00E+00tkm of dieselpowered barge transport needs9.59E03L of diesel. Therefore, the amount of diesel required in thegeneration of 1kWh of electricity can be determined as follows:
1.00E+00L of mechanical energyresults in the emission of 2.73E+00kg of carbon dioxide and6.10E06kg of methane. Therefore, the emissions associated with thegeneration of 1kWh electricity by combustion of diesel in industrialboiler is determined as follows
To generate1kWh of electricity, 2.29E03tkm of dieselpowered combination trucktransport is needed. Also, 1.00E+00tkm of dieselpowered combinationtruck transport needs 2.72E02L of diesel. Therefore, the amount ofdiesel required in the generation of 1kWh of electricity can bedetermined as follows:
1.00E+00L ofmechanical energy results in the emission of 2.73E+00kg of carbondioxide and 6.10E06kg of methane. Therefore, the emissionsassociated with the generation of 1kWh electricity by combustion ofdiesel in industrial boiler is determined as follows
To generate1kWh of electricity, 4.61E01tkm of dieselpowered train transport isneeded. Also, 1.00E+00tkm of dieselpowered train transport needs6.48E03L of diesel. Therefore, the amount of diesel required in thegeneration of 1kWh of electricity can be determined as follows:
1.00E+00L ofmechanical energy results in the emission of 2.73E+00kg of carbondioxide and 6.10E06kg of methane. Therefore, the emissionsassociated with the generation of 1kWh electricity by combustion ofdiesel in industrial boiler is determined as follows
Natural gas, combusted in industrialboiler. 1.00E+00m^{3} of mechanical energy from natural gasrequires 1.99E01tkm by combination truck. To generate 1kWh ofelectricity, 2.99E03tkm is required. Therefore, the amount ofmechanical energy from natural gas needed to generate 1kWh ofelectricity can be determined as follows
1.00E+00m^{3}of mechanical energy results in the emission of 1.96E+00kg of carbondioxide and 3.60E05kg of methane. Therefore, the emissionsassociated with the generation of 1kWh electricity by combustion ofnatural gas in industrial boiler is determined as follows
1.00E+00m^{3} of mechanicalenergy from natural gas requires 1.12E02tkm by train. To generate1kWh of electricity, 4.61E01tkm is required. Therefore, the amountof mechanical energy from natural gas needed to generate 1kWh ofelectricity can be determined as follows
1.00E+00m^{3}of mechanical energy results in the emission of 1.96E+00kg of carbondioxide and 3.60E05kg of methane. Therefore, the emissionsassociated with the generation of 1kWh electricity by combustion ofnatural gas in industrial boiler is determined as follows
1.00E+00kg of bituminous coalrequires 8.70E04L of residual fuel oil to combust. To generate 1kWhof electricity, 4.42E01kg of bituminous coal are needed. Therefore,the amount of residual fuel oil needed to generate 1kWh ofelectricity can be determined as follows
1.00E+00L of residual oil results inthe emission of 3.26E+00kg of carbon dioxide and 1.28E04kg ofmethane. Therefore, the emissions associated with the generation of1kWh electricity by combustion of natural gas in industrial boiler isdetermined as follows
Question6: Global Warming Potentials
The globalwarming potentials (GWP) for a time horizon of 20 years weredetermined to be 1 and 72 for carbon dioxide and methanerespectively. The GWP for a 100 yeartime horizon were determined tobe 1 and 25 for carbon dioxide and methane respectively (IPCC, 2007).
Question7: Calculating Global Warming Potential (GWP)
Table1: GHG emissions and GWP per kWh
Question8: Life Cycle Stage in the largest GWP
The naturalgas, combusted in industrial boiler had the largest GWP. Thesefigures will still be higher when compared to the emissions thatwould result from the production of electricity using a wind turbine.This is so because the emissions from the latter life cycle areminimal and limited to the building and replacement of turbines andtransmission cables (Larson, 2013). These processes occur over aconsiderably wider period as compared to the combustion of naturalgas in an industrial boiler.
Question9: Increase in GWP of Methane
The GWPassociated with the generation of 1kWh of electricity from bituminouscoal would increase considerably. The output to nature of Methanewould also increase since the life cycle stages involved will eachcontribute a significant percentage of emissions of methane into theatmosphere. Processes such as transportation of the coal by train,combination truck, and transportation by barge would all contributeto the emissions. The amount of coal needed to produce 1kWh ofelectricity may remain constant but inputs/outputs associated withmoving one tonne of material over a kilometer will increase (Spath,Mann, & Kerr, 1999).
Question10:
Transportationof the coal to power plant is one of the lifecycle stages that isrepresented in the flow chart. The trains, trucks, and barges used totransport coal and natural gas, all use fossil fuel in theiroperations. The processes involved in the extraction, distillation,and refining the fuel for use in these vehicles contributes to theemission of greenhouse gases into the atmosphere (Fulton, Mellquist,Kitasei, & Bluestein, 2011). The emissions that are contributedby the combustion of fuel also contribute to the GWP but were notincluded in the data collection process.
Production andpreparation of the gases and coal used to generate steam to turn theturbines were also not included in the data collection process. Theseprocesses involved the use of heating and cooling systems, which alsocontribute to emissions.
UsingLife Cycle Assessment Results to Inform DecisionMaking for WindFarming Siting in HRM
Question11
The generatedvalue of the GWP was 9.94E01kgCO_{2}/kWh. This value fallswithin the range (825 – 1700gCO_{2}/kWh) of values given.Expressed as a percentage of the mean of the 12 studies, the valuecan be represented as follows:
The value isclose to the mean value and differs only slightly from the mean. Thevalues may differ slightly from the published values because ofmathematical errors that arise due to the preference of certaindecimal places or significant numbers. Considering that the mean isderived from a number of research studies, there may have beenexperimental variations or conditions that may not have applied tothe data acquisition process leading to the generation of the GWPvalue.
Question12
The least GHGemission is that from natural gas.
Life cycle GHGemissions for biomassfuelled electricity generation are relativelylower compared to that of the natural gas fired electricitygeneration. The biomass life cycle has a mean of about 75g CO_{2}/kWhwhile that of natural gas stands at about 575g CO_{2}/kWh.
Question13: Total Amount of Electricity
Total amount ofelectricity used = 11, 244GWh + 1, 202GWh = 12,446 GWh
Feedstock 
Electricity Generated by NSPI (GWh) 
Electricity Purchased by NSPI (GWh) 
Percentage Contribution of All Electricity Generated (%) 
Coal 
6,609 
58.78 

Oil 
1553 
13.81 

Natural Gas 
1,468 
353 
13.06 
Hydro 
1,100 
9.78 

Wind 
256 
849 
2.28 
Biomass 
258 
2.29 

Total 
11,244 
1,202 
100 
Table2: Total amount of electricity used in NS in 2014
Coal accounts for 58.78% ofelectricity generation in Nova Scotia. This is the largest share ascompared to other feedstock. Wind, on the other hand, contributes2.28% to the total generated electricity used in Nova Scotia.
Question 14
a) Average GHG emissions per kWh foreach of the five main generation feedstocks used in Nova Scotia in2014.
Coal GHG emissions = 1000gCO_{2}/kWh Oil GHG emissions = 775g Co_{2}/kWh
Wind GHG emissions = 17.5gCO_{2}/kWh Natural gas GHG emissions = 575g CO_{2}/kWh
Hydro GHG emissions = 10g CO_{2}/kWh
B) Calculation of weighted averageGWP (in CO_{2} equivalents)
The GWP associated with electricityemission in CO2_{ }equivalents is given as 2.23E04kWh
GHG emissions = Activity data(electricity by source) x Emission conversion factor (GWP)
For coal, weighted GWP = 1kg CO_{2}/ kWh / 6.609E+09kWh = 1.23E05kg CO_{2}/kWh
For oil, weighted GWP = 0.775kgCO_{2}/kWh / 1.553E+09kWh = 2.23E05kg CO_{2}/kWh
For natural gas, weighted GWP =.575kg CO_{2}/kWh / 1.468E+09kWh = 1.98E05kg CO_{2}/kWh
For hydro, weighted GWP = 0.010kgCO_{2}/kWh / 1.100E+09kWh = 3.01E6kg CO_{2}/kWh
For Wind, weighted GWP = 0.0175kgCO_{2}/kWh / 2.56E+09kWh = 2.61E06kg CO_{2}/kWh^{ }
For biomass, weighted GWP = 0.075kgCO_{2}/kWh / 2.58E+09kWh = 5.39E06kg CO_{2}/kWh
One major assumption in thecalculation of the weighted GWP is that the emission factor is basedon the exact fuel that was fired to generate the electricity and thetechnology employed. Calculating carbon dioxide emissions associatedwith electricity consumption can be calculated using marginal oraverage rates. In this particular instance, the average rates wereused as they were assumed to yield more accurate representativevalues.
Question 15: Maximumelectricity generated by turbines
Wind power potential, P = 0.5CAρVwhere C = efficiency, A= area intercepted by the blades, 64metres indiameter p = density of air taken to be 1.225kg/m^{3} and v=velocity of the wind = 12.5m/s
P = 0.5 x 100 x 3.14 x 32^{2}m^{2} x 1.225kg/m^{3} x 12.5m/s = 2,461.76kWh perturbine.
Total potential = 2,461.76kW x 11wind turbines = 27,079.36 kWh
Question 16:
Wind power potential, P = 0.5CAρVwhere C = efficiency, A= area intercepted by the blades, 64metres indiameter p = density of air taken to be 1.225kg/m^{3} and v=velocity of the wind = 12.5m/s
P = 0.5 x 30 x 3.14 x 32^{2}m^{2} x 1.225kg/m^{3} x 12.5m/s = 738.528kWh perturbine.
Total potential = 738.528kW x 11wind turbines = 8,123.808 kWh
Question 17
Average emissions for 1kWh = 17.5 gCO_{2. }The 11 turbines generate a total of 8,123.808kWh.
Therefore, the amount of emissionscan be determined as follows:
(8,123.808kWh x 17.5 g CO_{2})/1kWh = 142,166.64g CO_{2} = 142.17kg CO_{2}
Question 18
The average emissions for 1kWh ofelectricity from wind is given as 17.5g of CO_{2}. If the 11turbines were to replace coal and thus produce 6, 609, 000, 000kWh ofelectricity, total emissions of CO_{2} would stand at:
(6, 609, 000, 000 kWh x 0.0175kgCO_{2}) / 1kWh = 115, 657, 500kg CO_{2}.
In comparison, coal generates about1kg CO_{2} emissions per KWh. Therefore, 6,609,000,00kWhwould result in the generation of 6,609,000,000kg CO_{2}worth of emissions.
Consequently, the 11 turbines wouldgreatly reduce the carbon emissions if they were to take over fromthe coalfired system of electricity production. The exact figure ofreduction can be determined as follows:
6,609,000,000kg CO_{2 }115, 657, 500kg CO_{2} = 6, 493, 342, 500kg CO_{2}
The reduction can also be expressedas a fraction of the total 2014 GWP of all electricity generated inNS.
Average carbon emissions per kWh ofelectricity are given. Using the GWP of Carbon for a 20year timehorizon (GWP = 1), it is possible to calculate the total GWP asfollows:
Feedstock 
Electricity Generated by NCPI 
Emissions kg CO_{2}/kWh 
Emissions kg CO_{2} 
Emissions kg CO_{2} on substitution of coal by wind 
GWP 

+Coal 
Coal 

Coal 
6,609,000,000 
1 
6,609,000,000 
– 
1 
– 
Oil 
1,553,000,000 
0.775 
1,203,575,000 
1,203,575,000 
0.775 
0.775 
Natural Gas 
1,468,000,000 
0.575 
4,480,000 
4,480,000 
0.575 
0.575 
Hydro 
1,100,000,000 
0.010 
844,100,000 
844,100,000 
0.010 
0.010 
Wind 
256,000,000 
0.0175 
19,350,000 
115,657,500 
0.0175 
0.0175 
Biomass 
258,000,000 
0.075 
11,000,000 
11,000,000 
0.075 
0.075 
Total 
11,244,000,000 
8,691,505,000 
2,193,682,500 
2.4525 
1.4525 
Table3: GHG emissions and GWP
The GWP would thus decrease by 1. Asa fraction, this value translates to 1/ 2.4525 = 0.408 = 400/981 oftotal 2014 GWP.
Question 19
As calculated in Question 16 above,the amount of electricity each turbine can generate was found to be738.528kWh. Therefore, under the new setback law, the 7 turbines willcollectively generate:
738.528kWh x 7 = 5,169.696kWh
Initially the 11 turbines generated142.17kg CO_{2} of emissions.
Average emissions for 1kWh = 17.5 gCO_{2. }The 7 turbines generate a total of 5,169.696kWh.
Therefore, the amount of emissionscan be determined as follows:
(5,169.696kWh x 17.5 g CO_{2})/1kWh = 142,166.64g CO_{2} = 90.470kg CO_{2}
From the calculations above, it isevident the 7 turbines will generate lesser GHG as compared to the 11turbines. In figures, this translates to 142.17kg CO_{2} 90.470kg CO_{2} = 51.7 kg CO_{2} less GHG emissions.
Implications
From the analysis above, it isevident the enactment of the new setback bylaw will see aconsiderable reduction in the production of greenhouse gases and thesubsequent emissions. However, the move also implies that the amountof electricity generated will be less and, therefore, other sourcesmay be deployed to cover the deficit. HRM may purchase electricityfrom other provinces or countries to cover the deficit. This movewill have implications such as incurring more costs in setting upgrid lines and substations to supply the purchased power. Theconstruction of these facilities and the infrastructure will resultin generation of GHG. Whereas the new bylaw will see a reduction inproduction of GHG, the measures that will be taken to cover thedeficit of electricity supply will also contribute to GHG emissionsbesides the increased costs.
References
Fulton, M., Mellquist, N., Kitasei, S., & Bluestein, J. (2011). Comparing lifecycle greenhouse gas emissions from natural gas and coal. World Watch Institute, Deutsche Bank Group.
IPCC. (2007). Publications and data: 2.10.2 Direct global warming potentials. Retrieved from Intergovernmental panel on climate change: https://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch2s2102.html
Larson, E. D. (2013). Natural gas and climate change. Princeton, NJ: Climate Central.
Spath, P. L., Mann, M. K., & Kerr, D. R. (1999). Lifecycle assessment of coalfired power production. Colorado: National Renewable Energy laboratory.