Energy Consumption and CO2 Emission 11-28-2012

8/10/2019 Energy Consumption and CO2 Emission 11-28-2012

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Calculation of Energy Comsuption and CO2 Emisions 11/28/2012

Figure 4-1. LCA model

Table 2-2. LCI of Energy used for Asphalt Pavement

Sub-stepMaterial or

process

Energyconsumption

(J/t of material)

Total energyconsumed for

1 ton ofasphalt

pavement(MJ)

Contributionto the sub-

step (%)

Totalenergy

consumed(%)

Raw materialsextraction andinitialtransformation

Bitumen 0 0 0

6.69Aggregates 5.30x10 7 2.53x10 5 100

Subtotal 2.53x10 5 100

Manufacturing

Production ofbitumen

6.00x10 9 1.51x10 6 43

91.54

Storage ofbitumen

5.43x10 8 1.36x10 5 4

Asphaltmixing anddrying ofaggregates

3.62x10 8 1.82x10 6 53

Aggregates 0 0 0Subtotal 3.46x10 6 100

PlacementAsphalt 1.34x10 7 6.70x10 4 100

1.77Subtotal 6.70x10 4 100

Total 3.78x106

100


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Table 2-3. LCI of Energy used for PCC Pavement

Sub-step Material or processEnergy

consumption(J/t of material)

Total energyConsumedfor 1 ton of

PCC pavement(MJ)

Contribu-tion to the

sub-step(%)

Totalenergy

consumed(%)

Raw materialsextraction andinitialtransforma-tion

Portland cement 0 0 0

3Coarse aggregates 5.3x10 8.38x10 58Fine aggregates 5.3x10 5.46x10 38Reinforcing steel 5.3x10 7 6.61x10 3 5Subtotal 1.45x10 100

Manufactur-

ing

Portland cement 6.33x10 2.80x10 65

94

Coarse aggregates 0 0 0Fine aggregates 0 0 0

Reinforcing steel 1.90x10

1.48x10 34Concrete mixing 6.875x10 6 2.53x10 4 1Subtotal 4.31x10 6 100

PlacementConcrete 3.4x10 1.25x10 100

3Rebar 0 0 0Subtotal 1.25x10 5 100

Total 4.58x10 100

Table 2-4. Environmental Loads through the Life Cycle of Highways

Process Energy

(TOE/FU)

NO x

(ton/FU)

SO 2

(ton/FU)

CO 2

(T-C/FU)Manufacturing of constructionmaterials

1,525.7 9.8 35.4 1,391.4

Construction 47.1 0.3 1.1 41.7Maintenance and repair 1,069.4 6.8 24.8 976.5Demolition 34.5 0.2 0.8 28.9

Total 2,676.7 17.1 62.1 2,438.5 Note: TOE: ton of oil equivalent; FU: functional unit (one km of 4 lane highway)

Table 4.3 Unit energy consumption in materials production stage

Material Unit Energy consumption(GJ)

Reference

1. Aggregates ton 0.038 (Stripple 2001)2. Concrete m (PCA 2006)

35MPa 2.2830MPa 1.9920MPa 1.69

3. Asphalt bitumen ton 2.93 (Stripple 2001)4. Steel ton 15.42 (IISI 2000)5. RAP ton 0.054 (PaLATE v2.1)6. RCP ton 0.16 (PaLATE v2.1)


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Energy conversion factor: convert electricity/fuel to universal energy.

Table 4-4. Conversion factor and calorific values of fossil fuel (UKDTI 2006)

Electricity Diesel Burning oil LPG Natural gas CoalUnit MJ/kWh MJ/kg MJ/kg MJ/kg MJ/m MJ/kgValue 3.6 45.7 46.2 49.5 39.6 25.6

LPG: liquefied petrolium gas

Once energy consumption has been calculated, emissions can be determined accordingly.

Convert material quantities to CO2

Table 4-5. Unit GHG emissions from the production of some materials (Stripple 2001)

MaterialUnit emission (kg/ton,m ) CO 2

equivalent(kg-CO 2e)

CO 2 CH 4 N2O

1. Aggregates (ton) 1.42 3.82E-06 3.61E-05 1.432. Concrete 35MPa (m3) 328 3.15E-05 1.95E-04 3283. Bitumen (ton) 173 3.53E-05 1.06E-04 1734. Steel (ton) 2,220 9.17 3.06E-02 2,460

Note: - Concrete used in road & bridge construction usually has the strength of 35MPa.

- Emissions from above materials are CO 2 , CH4 , N2O only.

Emission conversion factor is used to convert fossil fuel or electricity to CO 2 equivalent(USEPA 2011).

Table 4-6. Emission conversion factor of diesel and electricity to CO 2e

Energy type Unit Kg-CO 2e/liter, kWh

Diesel Liters 2.663Electricity kWh 0.7


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Calculation of environmental impacts

a) Energy consumption and GHG emissions

Table B-1. Energy and GHG emissions of construction material production for earthwork

Material Quantity(m3)

Unit

Energy

(GJ)

Unit CO 2

Emission

(kgCO 2e)

Energy(GJ) CO2e (ton)

Concrete fordrainage 72,498 2.28 328 165,296 23,779

Where, Energy consumption

= (Quantity of materials) x (unit energy consumption for material production)

CO 2e emission

= (Quantity of materials) x (unit CO 2 emission for material production).

Unit energy consumption for material production is referred to Table 4-3 and unit CO 2

emission for material production is from Table 4-5. As shown in Table B-1, Energy

consumption of drainages concrete production = 72,498 (m 3) x 2.28 (GJ/m 3) = 165,296 (GJ);

CO 2e emission of drainages concrete production = 72,498 (m3) x 328 (kg-CO 2e/m

3) =

23,779,000 (kg-CO 2e) = 23,779 (ton-CO 2e)

Appendix A: Specification of equipment (Source: PaLATE 2.1)

Activity Equipment Brand/modelEngine

capacity(hp)

Productivity

(tons/h)

Fuelconsumption

(l/h)

Fuel

type

Concretepaving

Slipform paverWirtgen SP250 106 564 19.7 Diesel

Wirtgen SP500 178 1,150 32.5 Diesel

Crushingplant

Excavator John Deere 690E 131 315 34.2 Diesel

Dozer Caterpillar D8N 285 250 71.3 Diesel


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Table B-2. Energy and GHG emissions of construction equipment for earthwork

Earthwork

activityEquipment

Quantity

(m3)

Quantity

(tons)

Operation

hoursFuel (l)

Energy

(GJ)

GHG

emissions

(ton-CO2e)

1. Top soilremoval Dozer 4,580,315 9,112,669 36,451 2,598,933 100,956 6,921

2. Commonexcavation Excavator 11,587,917 34,581,742 109,783 3,754,589 145,847 9,998

3. Rockexcavation Excavator 5,792,109 17,285,351 54,874 1,876,695 72,900 4,998

Total 319,703 21,917

Where,

Operation hours = (Quantity of construction activity) / (Productivity rate of equipment)

Fuel consumption = (Operation hours) x (Unit fuel of equipment)

Energy consumption = (Fuel consumption) x (Energy conversion factor)

GHG emission = (Fuel consumption) x (Emission conversion factor)

Productivity rate and unit fuel of equipment are referred in Appendix A. Energy conversion

factor is referred in Table 4-4 and emission conversion factor is from Table 4-6. For example,

Operation hours for top soil removal = (quantity of top soil removal) x (Productivity of

dozer) = 9,112,669 (tons) / 250 (tons/h) = 36,451 (h).

Fuel consumption of top soil removal = (Operation hours) x (Unit fuel of dozer) =

36,451 (h) x 71.3 (l/h) = 2,598,933 (l).

Energy consumption of top soil removal = (Fuel consumption) x (Energy conversion factor)

= 2,598,933 (l) x 38.845 (MJ/l) = 100,956, 000 (MJ) = 100,956 (GJ).

GHG emission of top soil removal = (Fuel consumption) x (Emission conversion factor) =

2,598,933 (l) x 2.663 (kg-CO 2e/l) = 6,921,000 (kg-CO 2e) = 6,921 (ton-CO 2e)


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Table 4-9. Environmental impacts from earthwork of HL highway

Environmental

ImpactsUnit

Material

productionConstruction Mainten-ance

Disposal/

RecyclingTotal

1. Materialconsumption ton 181,246 181,246 0 0

362,492

2. Energyconsumption GJ 165,296 322,871 0 3,168

491,336

3. GHGemissions

ton-CO2e 23,779 22,134 0 109 46,022

4. Solid waste ton 314 4,531 0 45,311 50,156

Figure 4-5. Environmental impacts from earthwork of HL highway


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Extra inventory

Mroueh et al (2000). L ife Cycle Assessment of Road Construction . Report of Finish

National Road Aministration.

Environmental loadings caused by road maintenance over period of 50 years comparedwith the loadings caused by road construction

Nisbet et al (2001). Envir onmental L ife Cycle I nventory of Por tland Cement Concrete .Report of Portland Cement Association, United State.

Embodied energy by Process Step for 200MPa (3,000 psi) Mix


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Nairobi (1991). Energy for bui ldin g I mproving Energy Ef fi ciency in Constru ction andProduction of B ui ldin g M ateri als in Developing Countri es . United National Centre forHuman Settlement. ISBN 92-1-131 174-8.

Primary energy requirement of various materials and metal products

Documents

Energy Consumption and CO2 Emission 11-28-2012