Life Cycle Assessment Lab Report

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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 coal-fired 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 electricity-generatingnuclear 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:

  1. Coal

  2. Natural gas

  3. Wind

  4. Oil

  5. Hydro, solar, and biomass. (Fulton, Mellquist, Kitasei, &amp Bluestein, 2011)

Question 3: Process Flow Chart

Figure1: Processes involved in coal-fired 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, 4.42E-01kg ofbituminous coal is required as an input. Also, for every 1.00E+00kgof bituminous coal mined, there are 3.99E-03kg 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 diesel-powered barge transport associated withamount of coal required to generate 1kWh of electricity, 5.59E-02tkmof barge transport is used. Also, for every 1.00E+00tkm of bargetransport, there are 6.49E-07kg of fossil methane emitted and2.81E-02kg 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 diesel-powered combination truck associated withamount of coal required to generate 1kWh of electricity, 2.99E-02tkmof barge transport is used. Also, for every 1.00E+00tkm of bargetransport, there are 1.29E-06kg of fossil methane emitted and7.99E-02kg 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 diesel-powered train transport associated withamount of coal required to generate 1kWh of electricity, 4.61E-01tkmof barge transport is used. Also, for every 1.00E+00tkm of bargetransport, there are 9.05E-07kg of fossil methane emitted and1.89E-02kg 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, 1.62E-04m3of natural gas is combusted in an industrial boiler. Also, to produce1kWh of electricity, 4.42E-01kg of bituminous coal is combusted.Therefore, the amount of natural gas needed to generated 1kWh ofelectricity can be determined as follows:

1.00E+00m3of natural gas combusted in industrial boiler produces 1.96E+00kg ofcarbon dioxide emissions and 3.60E-05 methane emissions. Theemissions associated with combusting 7.1604E-06m3of natural gas to produce 1kW of electricity can be determined asfollows:

To generate1kWh of electricity, 4.42E-01kg of coal is burned. Burning 1.00E+00kgof coal in an industrial boiler leads to the emission of 2.63E+00kgof carbon dioxide and1.15E-04kg 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, 5.59E-02tkm of diesel-powered barge transport isneeded. Also, 1.00E+00tkm of diesel-powered barge transport needs9.59E-03L 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 and6.10E-06kg 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, 2.29E-03tkm of diesel-powered combination trucktransport is needed. Also, 1.00E+00tkm of diesel-powered combinationtruck transport needs 2.72E-02L 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 6.10E-06kg 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, 4.61E-01tkm of diesel-powered train transport isneeded. Also, 1.00E+00tkm of diesel-powered train transport needs6.48E-03L 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 6.10E-06kg 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+00m3 of mechanical energy from natural gasrequires 1.99E-01tkm by combination truck. To generate 1kWh ofelectricity, 2.99E-03tkm is required. Therefore, the amount ofmechanical energy from natural gas needed to generate 1kWh ofelectricity can be determined as follows

1.00E+00m3of mechanical energy results in the emission of 1.96E+00kg of carbondioxide and 3.60E-05kg of methane. Therefore, the emissionsassociated with the generation of 1kWh electricity by combustion ofnatural gas in industrial boiler is determined as follows

1.00E+00m3 of mechanicalenergy from natural gas requires 1.12E-02tkm by train. To generate1kWh of electricity, 4.61E-01tkm is required. Therefore, the amountof mechanical energy from natural gas needed to generate 1kWh ofelectricity can be determined as follows

1.00E+00m3of mechanical energy results in the emission of 1.96E+00kg of carbondioxide and 3.60E-05kg 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 8.70E-04L of residual fuel oil to combust. To generate 1kWhof electricity, 4.42E-01kg 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 1.28E-04kg 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 year-time 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, &amp Kerr, 1999).

Question10:

Transportationof the coal to power plant is one of the life-cycle 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, &amp 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 Decision-Making for WindFarming Siting in HRM

Question11

The generatedvalue of the GWP was 9.94E-01kgCO2/kWh. This value fallswithin the range (825 – 1700gCO2/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 biomass-fuelled electricity generation are relativelylower compared to that of the natural gas fired electricitygeneration. The biomass life cycle has a mean of about 75g CO2/kWhwhile that of natural gas stands at about 575g CO2/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 = 1000gCO2/kWh Oil GHG emissions = 775g Co2/kWh

Wind GHG emissions = 17.5gCO2/kWh Natural gas GHG emissions = 575g CO2/kWh

Hydro GHG emissions = 10g CO2/kWh

B) Calculation of weighted averageGWP (in CO2 equivalents)

The GWP associated with electricityemission in CO2 equivalents is given as 2.23E-04kWh

GHG emissions = Activity data(electricity by source) x Emission conversion factor (GWP)

For coal, weighted GWP = 1kg CO2/ kWh / 6.609E+09kWh = 1.23E-05kg CO2/kWh

For oil, weighted GWP = 0.775kgCO2/kWh / 1.553E+09kWh = 2.23E-05kg CO2/kWh

For natural gas, weighted GWP =.575kg CO2/kWh / 1.468E+09kWh = 1.98E-05kg CO2/kWh

For hydro, weighted GWP = 0.010kgCO2/kWh / 1.100E+09kWh = 3.01E-6kg CO2/kWh

For Wind, weighted GWP = 0.0175kgCO2/kWh / 2.56E+09kWh = 2.61E-06kg CO2/kWh

For biomass, weighted GWP = 0.075kgCO2/kWh / 2.58E+09kWh = 5.39E-06kg CO2/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/m3 and v=velocity of the wind = 12.5m/s

P = 0.5 x 100 x 3.14 x 322m2 x 1.225kg/m3 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/m3 and v=velocity of the wind = 12.5m/s

P = 0.5 x 30 x 3.14 x 322m2 x 1.225kg/m3 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 gCO2. 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 CO2)/1kWh = 142,166.64g CO2 = 142.17kg CO2

Question 18

The average emissions for 1kWh ofelectricity from wind is given as 17.5g of CO2. If the 11turbines were to replace coal and thus produce 6, 609, 000, 000kWh ofelectricity, total emissions of CO2 would stand at:

(6, 609, 000, 000 kWh x 0.0175kgCO2) / 1kWh = 115, 657, 500kg CO2.

In comparison, coal generates about1kg CO2 emissions per KWh. Therefore, 6,609,000,00kWhwould result in the generation of 6,609,000,000kg CO2worth of emissions.

Consequently, the 11 turbines wouldgreatly reduce the carbon emissions if they were to take over fromthe coal-fired system of electricity production. The exact figure ofreduction can be determined as follows:

6,609,000,000kg CO2 -115, 657, 500kg CO2 = 6, 493, 342, 500kg CO2

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 20-year timehorizon (GWP = 1), it is possible to calculate the total GWP asfollows:

Feedstock

Electricity Generated by NCPI

Emissions kg CO2/kWh

Emissions kg CO2

Emissions kg CO2 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 CO2 of emissions.

Average emissions for 1kWh = 17.5 gCO2. 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 CO2)/1kWh = 142,166.64g CO2 = 90.470kg CO2

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 CO2 -90.470kg CO2 = 51.7 kg CO2 less GHG emissions.

Implications

From the analysis above, it isevident the enactment of the new setback by-law 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 sub-stations to supply the purchased power. Theconstruction of these facilities and the infrastructure will resultin generation of GHG. Whereas the new by-law 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., &amp Bluestein, J. (2011). Comparing life-cycle 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/ch2s2-10-2.html

Larson, E. D. (2013). Natural gas and climate change. Princeton, NJ: Climate Central.

Spath, P. L., Mann, M. K., &amp Kerr, D. R. (1999). Life-cycle assessment of coal-fired power production. Colorado: National Renewable Energy laboratory.