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LifeCycleAssessment
Concrete Hollow Core Slab
Kynningsrud Prefab AB
Madumita Sadagopan [email protected]
Nelly Khmilkovska [email protected]
Samaneh Fazelinejad [email protected]
2
Acknowledgement
We would like to thank Lena Larsson ( Kynningsrud AB), Johan Hilmersson (SWEROCK AB) and Kim
Bolton (Högskolan i Borås) for giving us an understanding of the production process and allied
environmental impacts from their knowledge and experience.
The study has given us valuable opportunity to work with real-time data and develop our skills in life
cycle analysis.
3
Table of Contents
1. INTRODUCTION ............................................................................................................................... 5
1.1 Casting of a hollow core slab at Kynningsrud .................................................................................... 5
1.1.1 Constituents ............................................................................................................................... 5
1.1.2 Casting process .......................................................................................................................... 5
1.2 Extraction and crushing of rocks at Fröland ...................................................................................... 6
1.2.1 Extraction of fresh rock .............................................................................................................. 6
1.2.2 Crushing of refuse concrete ....................................................................................................... 6
2. GOAL & SCOPE .................................................................................................................................. 6
2.1 Goal ................................................................................................................................................... 6
2.1.1 CASE 1 ........................................................................................................................................ 7
2.1.2 CASE 2 ........................................................................................................................................ 9
2.2 System boundary ............................................................................................................................. 10
2.3 Functional unit ................................................................................................................................. 10
2.4 Assumptions and data received ...................................................................................................... 10
3. INVENTORY ANALYSIS ............................................................................................................... 12
3.1 Final inventory flow charts .............................................................................................................. 12
3.2 Extraction & crushing of rocks ......................................................................................................... 15
3.2.1 Case 1 ...................................................................................................................................... 15
3.2.2 Case 2 ...................................................................................................................................... 16
3.3 Production ....................................................................................................................................... 17
3.3.1 Case 1 ...................................................................................................................................... 17
3.3.2 Case 2 ...................................................................................................................................... 18
3.4 Transportation ................................................................................................................................. 18
3.4.1 Case 1 ...................................................................................................................................... 18
3.4.2 Case 2 ...................................................................................................................................... 19
4. IMPACT ASSESSMENT ................................................................................................................. 20
4.1 Impact category definition .............................................................................................................. 20
4.2 Classification .................................................................................................................................... 20
4.3 Characterization .............................................................................................................................. 21
4.3.1 Depletion of abiotic resources ................................................................................................. 21
4.3.2 Land use ................................................................................................................................... 21
4.3.3 Global warming ....................................................................................................................... 21
4.3.4 Human toxicity......................................................................................................................... 22
4.3.5 Acidification ............................................................................................................................. 23
4.3.6 Photochemical Ozone Creation Potential (POCP) .................................................................... 24
..................................................................................................................... Error! Bookmark not defined.
4.3.7 Eutrophication ......................................................................................................................... 26
5. DISCUSSION .................................................................................................................................... 26
5.1 PART I – SYNOPSIS OF IMPACT ASSESSEMENT ................................................................................ 26
4
5.2 PART II – Variation analysis ............................................................................................................. 27
6. CONCLUSIONS ................................................................................................................................ 28
7. REFERENCES .................................................................................................................................. 29
5
1. INTRODUCTION
The Kynningsrud Prefab AB situated in Uddevalla (Sweden), produces a range of concrete
prefabricated elements. The products range from slabs to walls and other pre-fabricated
building components.
Out of all the prefabricated products produced by Kynningsrud the hollow core slab was chosen
for evaluation because of its unique feature. At the casting stage a considerable amount of
concrete is left as refuse and is later reused as ballast stones in production of hollow cores.
The company is interested to make a comparison of the environmental impact of production of
hollow core with 10% re-used ballast versus a scenario without re-use.
1.1 Casting of a hollow core slab at Kynningsrud
1.1.1 Constituents
The finished concrete is a homogeneous mixture of the components below:
• Cement - 15%
• Ballast (Stones) – 70-80%
• Ballast (recycled) – 0-10%
• Steel strands – 4%
• Chemical – 1%
1.1.2 Casting process
Pre-stressed hollow core slabs are cast on casting lanes (casting beds) that are 90 meters long.
All the strands for one lane are stressed axially. The mixed wet concrete composed of the
constituents mentioned above is transported by an overhead transport system to the casting
lanes. The overhead system continuously extrudes the wet concrete over the casting beds.
Openings are made manually while the concrete slab hardens.
After tension of the strands is released, the slab is cut by length according to measured
markings. The two ends of the casted hollow core are cut along with the strands. These ends are
each 1m long. Each lane of 90m has 2m of concrete wastage from the cut ends that are further
called cut-offs in this study.
Fig. 1: Cut-offs
6
The finished slabs are checked for quality and right dimensions as per the requirements. As per
the information from Kynningsrud, the faulty products account to about 5% of the average
annual production and are rejected. The overhead crane then moves the finished slabs for
storage to be transported later. The casting lanes can be seen in Fig.2 below.
1.2 Extraction and crushing of rocks at Fröland
SWEROCK AB is the company provides machineries and services for rock extraction and crushing
of refuse concrete at Fröland.
1.2.1 Extraction of fresh rock
There are various machines employed for this process in SWEROCK where rocks are extracted,
crushed to different fractions and then sorted by size. The sorted fractions form the ballast that
the concrete is composed of. The fraction of readied ballast is transported by trucks to
Kynningsrud at a distance of 5km.
1.2.2 Crushing of refuse concrete
SWEROCK uses crushing machines in the quarry site to also crush refuse concrete delivered
from Kynningsrud. Initially Kynningsrud crushed its own concrete with a rented crusher instead
of transporting it to Fröland.
2. GOAL & SCOPE
2.1 Goal
Kynningsrud is the only company that uses refuse concrete in their hollow core elements with a
motive to be more sustainable. Hence the purpose of this study is to analyze and compare the
environmental impact of production with and without the use of refuse concrete. If this
Fig. 2
7
technique proves to be beneficial for the environment, it could be applied in other concrete
products that the company produces.
The aforementioned goal can be further refined as:
• Identifying hotspots in each case
• Compare production of hollow core slab with and without recycled ballast
• Discovering new applications if possible
The map below demonstrates the distances the trucks have to travel to the two stated
destinations: from Kynningsrud to SWEROCK in Fröland (5km), from Kynningsrud to Heljestrop
AB in Vänersborg.
2.1.1 CASE 1
The following diagram represents the initial flowchart for Case 1 showing the main process
scheme. It also shows the system boundary which is the scope of the study. It is to be noted
that the Constituents and Installation (assembly of hollow core) are kept outside because they
are not being analysed for. For details refer to the assumptions (Chapter 2.4).
25km
5km
8
KYNNINGSRUD
HOLLOW CORE SLAB
HELJESTROP AB – VÄNERSBORG (Landfill)
FRÖLAND
Fig. 4
EXTRACTION
TRANSPORT – 5 km
PRODUCTION
CRUSHING
BALLAST
ORIGINAL
TRANSPORT – 25 km
CONCRETE
REFUSE
CONSTITUENTS
Cement, water,
chemicals, steel
INSTALLATION
SYSTEM BOUNDARY
9
FRÖLAND
KYNNINGSRUD
HOLLOW CORE SLAB
2.1.2 CASE 2
From the Fig.5 above shows the schematics of Case 2 with the difference of crushing the refuse
concrete in Fröland instead of landfilling it in Heljestrop. The system boundaries seen above are
explained in greater detail in Chapter 2.2.
Fig. 5
EXTRACTION
CRUSHING
TRANSPORT – 5 km
BALLAST
ORIGINAL
BALLAST
RECYCLED
PRODUCTION
TRANSPORT – 5 km
CONSTITUENTS
Cement, water,
chemicals, steel
INSTALLATION
CONCRETE
REFUSE
10
2.2 System boundary
In order to fulfil the requirements of the goal the system boundary is defined from ‘cradle to
gate’, originating with the extraction of ballast from rock to the hollow core finished product
before its transportation to the assembly site. The boundary extends in Case 1 by transporting
the refuse concrete to the landfill leaving the recycling loop open. On the contrary Case 2 fulfils
the closed recycling loop when refuse concrete is reused after crushing by additional
transportation to the crushing site and back to the production site.
2.3 Functional unit
The functional unit is based on the end product which is a hollow core slab. The extraction,
production of the product and transportation of raw materials are governed by the weight which
is expressed in tonnage. This is the motivation behind choosing 1 tonne of hollow core as the
functional unit, which is easy for company representatives to relate to who are audience to this
study.
2.4 Assumptions and data received
In order to make this study fair and transparent it is necessary to make the following
assumptions and use real-time data when available:
• The constituent materials for the hollow core in weight percentage is given below:
MATERIALS CASE 1 (%) CASE 2 (%)
Cement 15 15
Ballast (Original) 80 70
Ballast (Recycled) 0 10
Steel strands 4 4
Chemicals 1 1
• The constituent materials excluding recycled and original ballast have been kept constant
by not analysing them for both cases 1,2. This is because they are at the same proportion
for both cases and will not make any difference in results for the set goal of the study.
• Cut-offs and faulty products are counted together and are treated as refuse concrete in
further chapters.
• It is as per specifications that all concrete spills containing water during production are
collected and the water is recycled fully.
11
• The dimensions of an average hollow core slab are neglected in this study for reasons
that the sizes vary for different orders and the functional unit (1 tonne) bears no relation
to this.
• In both the cases steel strands have been recycled and thus are kept constant, not
analysed.
• There is no landfilling of cut-offs or faulty products of hollow core in Case 2.
• The emissions and leachates arising out of landfilling of refuse concrete is Case 1 is
neglected in this study due to data insufficiency.
• Considering Case 1, about 20% of the refuse concrete was used for road building.
However, because of lack of data as to distance and location of roads this contribution is
assumed to be 0%.
• During production it assumed that the emissions arising out of electricity are neglected
because the consumption is the same for both cases.
• Oil used in production for warming the casting lanes is responsible for CO2 emissions, as it
is the only known emission from the production process and is within the study boundary.
• There is no wastage of ballast or refuse concrete during transportation and no trucks
return empty from a trip.
• The trucks used for transportation of original ballast and crushed concrete are Volvo FM
12 models, since they have been manufactured after 2000 they fall under the category of
Euro 3.
• The trucks used are semi-trailer types for long distance transport, as it is known that they
do not traverse city traffic.
• In Case 2 the original ballast and crushed concrete are delivered in different trucks of
above stated type.
• According the product specifications, the trucks used for delivery have a mileage of 4.5
litres of Diesel/mile.
• Water is not used for extraction of rock and the environmental impact of dynamite used is
not taken into account in this study because of lack of data.
• All machinery in SWEROCK use diesel as fuel.
• For Case 1 the diesel consumed by machinery for extracting original ballast and crushing
concrete (in Kynningsrud) are the same and each account 1.4 litres/tonne.
• For Case 2 the diesel consumed by machinery for extracting original ballast and crushing
concrete (in SWEROCK) are the same and each account 1.4 litres/tonne.
12
• The only emissions considered in operations in SWEROCK arise from use of diesel in
machinery.
• To arrive at the emissions from diesel for Case 1 and 2, the emissions arising from oil were
taken from Hitchhiker’s guide [1] for all processes, because no data for diesel was
available.
• Decimals places have not been rounded up in the Inventory Analysis to not affect
accuracy.
3. INVENTORY ANALYSIS
Although the functional unit is chosen to be 1 tonne of finished product, we have to take into
account the refuse concrete which is an inevitable result of the production that is described
earlier in the introduction. The refuse concrete is the part of production process that makes a
difference in our study whether it is recycled or not.
The refuse concrete comes from two sources namely the cut ends and faulty products. The
faulty products form 5% of the average annual production. The percentage of cut offs was
calculated by the weight : length ratio for length of cut offs (2 meters) to length of concrete cast
over the entire lane (90 metres). Knowing that the cut offs weigh 0.47 tonnes the concrete cast
over the lane is calculated to be 21.15 tonnes. This accounts to 2.22% of 1 tonne of cast hollow
core.
The total concrete refuse amounts to 7.22% of 1 tonne of hollow core. The total concrete
produced to obtain 1 tonne finished hollow core including the refuse can be calculated by:
�. ������� = �(� − �. ����)
The received above number will be used to estimate the inflows and resulting outflows of
processes to obtain values per function unit of 1 tonne.
3.1 Final inventory flow charts
The subsequent charts represent the main processes with their inflows and outflows shown for
both Case 1 and 2.
13
FRÖLAND
KYNNINGSRUD
HOLLOW CORE SLAB
HELJESTROP AB – VÄNERSBORG (Landfill)
EXTRACTION DIESEL
DIESEL
CASE 1
EMISSIONS
EMISSIONS
TRANSPORT – 5 km DIESEL
BALLAST
ORIGINAL
PRODUCTION
TRANSPORT – 25 km
CONCRETE
REFUSE
EMISSIONS
ELECTRICITY
(Energy)
OIL (Energy)
CO2
DIESEL EMISSIONS
CRUSHING
14
FRÖLAND
KYNNINGSRUD
HOLLOW CORE SLAB
EXTRACTION DIESEL
CRUSHING DIESEL
CASE 2
EMISSIONS
EMISSIONS
TRANSPORT – 5 km DIESEL
BALLAST
ORIGINAL
BALLAST
RECYCLED
PRODUCTION
TRANSPORT – 5 km
CONCRETE
REFUSE
EMISSIONS
ELECTRICITY
(Energy)
OIL (Energy)
CO2
DIESEL EMISSIONS
15
3.2 Extraction & crushing of rocks
3.2.1 Case 1
Although there is crushing process in Case 1 for the refuse concrete, it is not shown in the table
below. This is because the crusher was rented in Kynningsrud and has been included in the
inventory table in Case 1 under production (Chapter 3.2.1)
Conversion from Litre to MJ
To convert diesel from litre to Mega Joules to enable calculations the following is done:
1 litre (diesel) = 35.67568 MJ [2]
���������(������.�) = ��������� ����� ∗ "����#���$�$(������. �)
Example:
%&�����.� = �', �� ����� ∗ ), ���(������. �) = �*+, ��(������.�)
The table below gives the inflows and outflows for extraction process Case 1.
EXTRACTING (Case 1)
INFLOW
Given Data Unit /F.U Unit
Diesel - for original ballast
1,40 lt/tonnes 43,06717121 MJ
OUTFLOW
Ballast - original 0,862275449 Tonnes
CO2 75,8 gr/MJ 3264,491578 gr
NOX- diesel 0,15 gr/MJ 6,460075682 gr
SO2- diesel 0,38 gr/MJ 16,36552506 gr
CO- diesel 0,013 gr/MJ 0,559873226 gr
HC- diesel 0,01 gr/MJ 0,430671712 gr
Particles- diesel 0,03 gr/MJ 1,292015136 gr
Ash- diesel 0,007 gr/MJ 0,301470198 gr
16
3.2.2 Case 2
In contrast with Case 1 above, the table below includes the crushing of refuse concrete at
SWEROCK (Fröland).
EXTRACTING (Case 2)
INFLOW
Given Data Unit /F.U Unit
Diesel for original ballast
1,40 lt/tonnes 37,68377481 MJ
OUTFLOW
Ballast - original 0,754491018 Tonnes
CO2 75,8 gr/MJ 2856,430131 g
NOX- diesel 0,15 gr/MJ 5,652566221 g
SO2- diesel 0,38 gr/MJ 14,31983443 g
CO- diesel 0,013 gr/MJ 0,489889073 g
HC- diesel 0,01 gr/MJ 0,376837748 g
Particles- diesel 0,03 gr/MJ 1,130513244 g
Ash- diesel 0,007 gr/MJ 0,263786424 g
���������(������.�) = ��������� ����� ∗ "����#���$�$(������. �)
The table in the following page shows the crushing and is included with extraction because both
operations take place in SWEROCK.
CRUSHING (Case 2)
INFLOW
Given Data Unit /F.U Unit
Diesel for crushing
1,40 lt/tonnes 3,888008512 MJ
recycled concrete
0,077844311 Tonnes
OUTFLOW
Ballast - recycled
0,107784431 0,107784431 Tonnes
CO2 75,8 gr/MJ 294,7110452 g
NOX- diesel- crushing
0,15 gr/MJ 0,583201277 g
SO2- diesel- crushing
0,38 gr/MJ
1,477443235 g
CO- diesel- crushing
0,013 gr/MJ
0,050544111 g
HC- diesel- crushing
0,01 gr/MJ
0,038880085 g
Particles- diesel- crushing
0,03
gr/MJ
0,116640255 g
Ash- diesel- crushing
0,007 gr/MJ
0,02721606 g
17
3.3 Production
3.3.1 Case 1
PRODUCTION (Case 1)
INFLOW
Given Data Unit Normalizing
(/tonne) /F.U Unit
Energy - Electricity cons.
1138637 kWh/yr 14,66843156 15,81028552 kWh
Energy - Oil cons.
132 m3/yr 0,001700483 0,001832856 m3
Ballast - original (tonnes) 80%
-- 0,862275449 Tonnes
Energy - diesel - for crusher rented
1,4 lt/tonnes 3,888008512 MJ
OUTFLOW
Hollow core -- 1 Tonnes
CO2 – oil* 273,00 g/m3 0,464231884 0,00085087 g
Solid Concrete waste - landfill- 100%
-- 0,077844311 Tonnes
Solid Concrete waste - road building - 0%
-- 0 Tonnes
CO2 - diesel -crushing
75,80 g/MJ 294,7110452 g
NOX- diesel- crushing
0,15 g/MJ 0,583201277 g
SO2- diesel- crushing
0,38 g/MJ 1,477443235 g
CO - diesel- crushing
0,013 g/MJ 0,050544111 g
HC- diesel- crushing
0,01 g/MJ 0,038880085 g
Particles- diesel- crushing
0,03 g/MJ 0,116640255 g
Ash - diesel- crushing
0,007 g/MJ 0,02721606 g
*The emissions arising out of the production process from the oil in both Case 1 and 2 is the same.
But the inclusion of the crusher in Case 1 in production itself makes a difference.
18
3.3.2 Case 2
PRODUCTION (Case 2)
INFLOW
Given Data Unit Normalizing
(/tonne) /F.U Unit
Energy - Electricity cons.
1 138 637 kWh/yr 14,66843156 15,81028552 kWh
Energy - Oil-cons.
132 m3/yr 0,001700483 0,001832856 m3
Ballast - original 70%
-- 0,754491018 Tonnes
Ballast - recycled 10%
-- 0,107784431 Tonnes
OUTFLOW
Hollow core (tonne)
-- 1 Tonnes
CO2-oil 273 g/m3 0,464231884 0,00085087 g
Solid Concrete waste -recycled (tonne) 100%
-- 0,077844311 Tonnes
3.4 Transportation
3.4.1 Case 1
The distances covered in Case 1 are – Fröland to Kynningsrud : 5 km
Distance from Kynningsrud – landfill in Vänersborg : 25 km
In the calculations below 1 mile = 1.6093 km
tkm refers to tonne x kilometre
TRANSPORTATION (Case 1)
INFLOW
Given Data
Unit /F.U Unit
Ballast - original- 80% 0,862275449 Tonnes
Energy - diesel - from production to landfill
4,5 Lt/miles 2493,882154 MJ
Energy - diesel - from extraction to production
4,5 Lt/miles 498,7764308 MJ
OUTFLOW
CO2 - diesel- to production site 52,00 g/tkm 224,1916168 g
NOX - diesel- to production site 0,33 g/tkm 1,422754491 g
HC -diesel- to production site 0,0470 g/tkm 0,202634731 g
PM- diesel- to production site 0,0057 g/tkm 0,02457485 g
CO- diesel- to production site 0,0460 g/tkm 0,198323353 g
SO2- diesel- to production site 0,0130 g/tkm 0,056047904 g
CO2 - diesel- to landfill 52,00 g/tkm 101,1976048 g
NOX – diesel to landfill 0,33 g/tkm 0,642215569 g
HC -diesel-to landfill 0,0470 g/tkm 0,091467066 g
PM- diesel-to landfill 0,0057 g/tkm 0,011092814 g
CO- diesel-to landfill 0,0460 g/tkm 0,089520958 g
SO2- diesel- to landfill 0,0130 g/tkm 0,025299401 g
19
3.4.2 Case 2
TRANSPORTATION (Case2)
INFLOW)
Given Data
Unit /F.U Unit
Energy - diesel -Ballast - original-70%
4,5 Lt/miles 498,7764308 MJ
Energy - diesel-Ballast - recycled- 10%
4,5 Lt/miles 498,7764308 MJ
Energy - diesel - crushed concrete to Fröland
4,5 Lt/miles 498,7764308 MJ
OUTFLOW
CO2 - diesel-Original Ballast to production site
52,00 g/tkm 196,1676647 g
NOX - diesel- Original Ballast to production site
0,33 g/tkm 1,24491018 g
HC -diesel- Original Ballast to production site
0,0470 g/tkm 0,177305389 g
PM- diesel- Original Ballast to production site
0,0057 g/tkm 0,021502994 g
CO- diesel- Original Ballast to production site
0,0460 g/tkm 0,173532934 g
SO2- diesel-Original Ballast to production site
0,0130 g/tkm 0,049041916 g
CO2 - diesel- concrete to Fröland 52,00 g/tkm 20,23952096 g
NOX - diesel- concrete to Fröland 0,33 g/tkm 0,128443114 g
HC -diesel- concrete to Fröland 0,0470 g/tkm 0,018293413 g
PM- diesel- concrete to Fröland 0,0057 g/tkm 0,002218563 g
CO- diesel- concrete to Fröland 0,0460 g/tkm 0,017904192 g
SO2- diesel- concrete to Fröland 0,0130 g/tkm 0,00505988 g
CO2 - diesel- recycled Ballast to production site
52,00 g/tkm 28,0239521 g
NOX - diesel- recycled Ballast to production site
0,33 g/tkm 0,177844311 g
HC -diesel- recycled Ballast to production site
0,0470 g/tkm 0,025329341 g
PM- diesel- recycled Ballast to production site
0,0057 g/tkm 0,003071856 g
CO- diesel- recycled Ballast to production site
0,0460 g/tkm 0,024790419 g
SO2- diesel- recycled Ballast to production site
0,0130 g/tkm 0,007005988 g
,-.//.01(234536. 7) = ,-.//.01( 238 ∗ 9-) ∗ :./8;1<5(9-) ∗ 8011;25(-;853.;=>036. 7)
20
Example:
%&�(24536. 7)fromFrölandtokynningsrud= 52( 2
8 ∗ 9-) ∗ 5(9-) ∗ 0,7545(-;853.;=>036. 7) =�*U, ��(24536. 7)
4. IMPACT ASSESSMENT
4.1 Impact category definition
The emissions resulting from the processes discussed have been defined in the following impact
categories:
• Depletion of abiotic resources
• Land use
• Global Warming
• Human Toxicity
• Photochemical ozone creation potential
• Acidification
• Eutrophication
4.2 Classification
The Fig 6 represents the cause-effect chain of environmental impacts. The first row signifies the
processes in this study, leading to the emissions of pollutants and as a consequence the last row
represents the primary effects caused. The secondary and tertiary effects arising from primary
effects and pollutants are not shown on the diagram, given that it is out of the scope of the
study.
Production Transportation Extraction
CO2 SO2 CO PM
HC
NOx
GWP Eutrophication Acidification Human
Toxicity POCP
Fig. 6
21
0,000
0,500
1,000
1,500
2,000
2,500
3,000
3,500
CASE 1 GWP100 years/F.U
CASE 2GWP 100 years/F.U
Production
Extr. & Crushing
Transportation
4.3 Characterization
Having defined the impact categories, analysing potential effects of the emissions calculated
from each process, it is possible to carry out classification.
4.3.1 Depletion of abiotic resources
Ballast stone has not been accounted for in depletion even though it is an abiotic resource and
is largely consumed in this study, because of its abundance in Sweden. There are no other
abiotic resources in this study.
4.3.2 Land use
According to the scope of the study the transport to landfill has been taken into consideration.
Even though the landfill is within the system boundary, the land use parameter is not studied
here. This is because real-time data was unavailable and assumptions were not chosen to be
made in order to avoid misinterpretation.
4.3.3 Global warming
Although the carbon dioxide is not the only gas that contributes to global warming, in this study
the results show the carbon dioxide as the only contributor [1].
The global warming potential (GWP) is chosen to be calculated for 100 years period as the most
common to use and since CO2- GWP for 20, 100 and 500 years are the same and equal 1.
CASE 1 CASE 2
Global warming potential Global warming potential
GWP 100 years (kg CO2 eqv/kg) 1 GWP 100 years (kg CO2 eqv/kg) 1
CO2 (kg) 3,884593 CO2 (kg) 3,395573
GWP 100 years
(kg CO2 eqv/per F.U)
3,884593 GWP 100 years
(kg CO2 eqv/per F.U)
3,395573
Fig. 7
22
0,000
2,000
4,000
6,000
8,000
10,000
12,000
14,000
16,000
18,000
SO2 PM SO2 PM
CASE 1 CASE 2
Production
Extr.&crushing
Transportation
4.3.4 Human toxicity
Toxicity impact category consists of human and eco toxicity. In this study there are no emissions
contributing to eco-toxicity, but contributor to human toxicity is present. The contributor is SO2
emitted from diesel mainly from transportation, extraction and crushing processes.
In this study emissions consist of Particulate Matter (PM) which arise from diesel in
transportation (PM 2.5 µm) and crushing (PM 10 µm). However the data is only available for
PM 10 (dust) and is what is being calculated for below:
As seen in the table above, by calculation it shows that SO2 emissions to air in the Case 1 is
3.8% higher than in Case 2. The PM for Case 1 is 4.8% higher than case 2 when calculated. This
change cannot be easily noticed in a histogram, which is the reason a histogram is not included
here. The same motivation will be implied to other impact categories as well.
CASE 1
Human Toxicity
Substance Total amount (kg) HTP - to air HTP - to air (per F.U)
SO2 (kg) 0,016488286 0,096 0,001582875
PM 10
(kg)
0,001330952 0,82 0,001091381
CASE 2
Human Toxicity
Substance Total amount (kg) HTP - to air HTP - to air (per F.U)
SO2 (kg) 0,015858385 0,096 0,001522405
PM 10
(kg)
0,001273947 0,82 0,001044636
Fig. 8
23
0,00
2,00
4,00
6,00
8,00
10,00
12,00
14,00
16,00
18,00
SO2 NOx SO2 NOx
CASE 1 CASE 2
Production
Extr.&crushing
Transportation
4.3.5 Acidification
It is known that the acidifying pollutants release H+ ions, which cause acidification. In this study
SO2 and NOx are major acidifying pollutants.
CASE 2
Acidification
Substance Amount (g) AP (g SO2 eqv/g) AP (g SO2 eqv/ F.U)
SO2 15.858385 1 15.85838545
NOx 7.7869651 0.7 5.450875572
CASE 1
Acidification
Substance Amount (g) AP (g SO2 eqv/g) AP (g SO2 eqv/ F.U)
SO2 16.48828554 1 16.48828554
NOx 8.541393047 0.7 5.978975133
Fig. 9
24
4.3.6 Photochemical Ozone Creation Potential (POCP)
Summer smog or POCP contributes to formation of ozone in lower layers of atmosphere, which is undesirable. The major contributors being CO, NO,
NO2 and SO2 are contributing to the fore mentioned impact. NOX emissions include NO and NO2 and arise from transportation and crushing processes.
Since data is available for both NO and NO2, the formula below is used to estimate NOX emissions. The emissions have been calculated in gram/tonne
which is equal to ppm.
V&WX���Y = V&X���Y�. *' ; V&WX���Y = V&+V&�
CASE 1
Photochemical ozone creation potential
Substance Total amount (kg) Low NOx POCPs
(kgethylene/kg)
Low NOx POCPs
(kgethylene per F.U)
MOIRs** (kg formed
ozone/ kg)
MOIRs (kgethylene per
F.U)
SO2 0,016488286 …. …. …. ….
CO 0,000849134 0,04 0,00003396537 0,029 0,00002462489
NO2 0,008533 …. …. …. ….
NO 0,008114 …. …. …. ….
CASE 2
Photochemical ozone creation potential
Substance Total amount (kg) Low NOx POCPs
(kgethylene/kg)
Low NOx POCPs
(kgethylene per F.U)
MOIRs (kg formed
ozone/ kg)
MOIRs (kgethylene per
F.U)
SO2 0,015858385 …. …. …. ….
CO 0,000756661 0,04 0,00003026643 0,029 0,00002194316
NO2 0,007780 …. …. …. ….
NO 0,007398 …. …. …. ….
*POCP – Photochemical Ozone Creation Potential
**MOIRs – Maximum Ozone Incremental Reactivities
25
0,00000000
0,00000500
0,00001000
0,00001500
0,00002000
0,00002500
LOW NOx POCPS -CASE 1
LOW NOx POCPS -CASE 2
Production
Extr.&crushing
Transportation
0,00000000
0,00000200
0,00000400
0,00000600
0,00000800
0,00001000
0,00001200
0,00001400
0,00001600
0,00001800
MOIRS (kgethylene perF.U) CASE 1
MOIRS (kgethylene perF.U) CASE 2
Production
Extr.&crushing
Transportation
The High NOx background concentrations are not considered in this study for this impact
category due to the following reasons:
1. According to [3] urban areas generally tend to have high NOx concentrations while
rural areas are likely to have low NOx concentrations.
2. According to Census 2006, Uddevalla has a population of about 31,000 inhabitants in
contrast urban areas such as Gothenborg has 5,10,000 inhabitants.
In this study the areas of interest are Fröland, Vänersborg and Uddevalla are not entirely
rural but is less urban compared to Gothenborg. Thus the high NOx concentrations are
excluded.
26
4.3.7 Eutrophication
Eutrophication is an effect of Nitrogen and Phosphorous concentrations on the ecosystems. In
this study NOx is a source of Nitrogen which again arises from the use of diesel in the processes.
CASE 1
Eutrophication
Substance Amount (g) (g PO₄⁻³
eqv/g)
(g PO₄⁻³ eqv/F.U)
NOx 8.541393047 0.13 1.110381096
CASE 2
Eutrophication
Substance Amount (g) (g PO₄⁻³
eqv/g)
(g PO₄⁻³ eqv/F.U)
NOx 7.786965103 0.13 1.012305463
The increase in NOx concentration from Case 1 to Case 2 is about 8.8% and is too small a change
to show on a histogram.
5. DISCUSSION
5.1 PART I – SYNOPSIS OF IMPACT ASSESSEMENT
• Global warming potential:
o As seen from the histogram Fig. 7 Case 1 altogether shows a higher contribution
to GWP as compared to Case 2. The most striking difference is observed in
production process. Case 1 has higher GWP compared to Case 2 in production
because a crusher was rented and used at the production site. The impact due
to emissions of the oil is same in both cases as it is consumed in same amounts.
o The biggest contributor to GWP in both cases is the extraction & crushing
process. This is because of the high consumption of diesel owing to higher
quantity of ballast having to be extracted. The gram emissions arising out of 1
MJ of fuel is higher for stationary machinery as compared to vehicles using
diesel [1].
o The difference in the GWP for transportation is because of different distances
in both cases. In Case 1 the total distance travelled are 30 km and 15 km for
Case 2.
• Human toxicity:
o From Fig. 8, Case 1 shows higher contribution to human toxicity for all 3
processes as compared to Case 2. The extraction process accounts to the
highest contribution of SO2 in both cases. The dependence on quantity of stone
extracted can be seen in cases 1 and 2. Case 1 requires 1.4 litres/tonne for
0.862 tonnes. But Case 2 requires 1.4 litres/tonne for 0.754 tonnes and 1.4
litres/tonne for crushing 0.077 tonnes to get recycled ballast. After analysing
the above data the Case 1 shows higher contribution because of quantity.
27
o The concentrations of SO2 and particulate matter are ‘0.00’ in production
process in Case 2 because there is no crusher used on site.
• Photochemical ozone creation potential:
o In both cases as shown in Figs.10,11,12 the extraction and crushing have
highest values for Low and high NOx and MOIRS.
o The NO emission has a positive effect in preventing ozone formation and in
Case 1 the NO emissions are higher than Case 2, thus Case 1 seems less harmful
for this impact category. But as seen from the Cause-effect chain (Fig.6) the NO
contributes also to acidification and eutrophication. Even though Case 1
reduces the chances of ozone creation it also has other harmful effects as
mentioned in the categories above.
• Acidification:
o As seen from the histogram Fig. 9 Case 1 seems to show a higher negative
impact towards acidification especially due to considerably higher shares of SO2
compared to NOx.
o The biggest contributor in both cases is the extracting and crushing process for
both emissions.
• Eutrophication:
o As only NOx contributes to eutrophication, the values for both Case 1 and 2 do
not show any significant difference. Hence it can be inferred that there is no
significant difference in both cases as far as eutrophication is concerned.
5.2 PART II – Variation analysis
The most impactful processes of this study have been extraction and transportation as it is
energy intensive and uses diesel as fuel. In reality in Cases 1 and 2, the destinations of landfill,
extraction, production are stationary and varying the distances would be futile in this case.
Varying the root cause of emission could lead to different results assuming the other conditions
in the study so far are kept constant.
Consequently diesel consumption is chosen to be substituted by bio-diesel. Considering that the
diesel engine is compatible with bio-diesel, it could be industrially feasible if implemented in a
bigger scale. In this study, The hitch hiker’s guide to LCA was chosen as reference. The table
below represents a scenario where bio diesel is used for the machineries in extracting and
crushing processes for Case 1, the transportation and production are still using non-renewable
fuels.
CASE 1 – Extraction & Crushing
Diesel Biodiesel
CO2 (gr/F.U) 3264.491578 0
NOX( gr/F.U) - crushing 6.460075682 5.794491018
SO2( gr/F.U) - crushing 16.36552506 1.158898204
CO( gr/F.U) - crushing 0.559873226 38.62994012
HC( gr)- diesel- crushing 0.430671712 3.862994012
Particles( gr/F.U)- crushing 1.292015136 1.158898204
Ash( gr/F.U)- crushing 0.301470198 3.862994012
28
As seen from the table, for CO2 emissions biodiesel has no contribution (CO2 neutral) and thus
does not contribute to global warming. This is the most striking decrease in amongst the other
emissions if bio diesel could be used.
Below in Fig. 13 a comparison is made for Case 1 for the use of bio-diesel vs. diesel for the
extraction and crushing process. The SO2 and PM pollutants contribute to human toxicity.
In Fig.13 the use of diesel emits much higher amounts of SO2 as compared with the use of bio
diesel. Similar conclusions can be drawn for PM but the difference is not substantial.
The anomalies in the table are seen for CO and HC emissions, the results received for these
after implementation of biodiesel is higher. This does not comply with the general knowledge
about motivation to use the biofuels. Thus this section of data is conflicting and is suggested to
be studied further.
6. CONCLUSIONS
The hotspots were identified individually by assessment for both Case 1 and 2. The results
revealed the extraction and crushing process to be the most environmentally impactful out of
transportation and production.
It is reflected from the assessments above, that diesel is the major contributor to emissions and
harmful environmental impacts. The most diesel intensive processes are extraction & crushing
and transportation.
The reduced amounts of emissions for Case 2 can be attributed to the lesser consumption of
diesel because recycling of ballast was implemented. A consequence of this was that lesser
ballast had to be extracted. The distance travelled for closed loop recycling between
Kynningsrud and Fröland is proved to be less impactful to the environment than the distance
between Kynningsrud and the landfill.
0,000
2,000
4,000
6,000
8,000
10,000
12,000
14,000
16,000
18,000
SO2 PM
CASE 1 - Biodiesel Vs. Diesel
Extr.&crushing with biodiesel
Extr. &crushing with diesel
Figs. 12: HUMAN TOXICITY
29
The variation analysis showed that implementing biodiesel in extraction and crushing would
largely decrease the global warming potential. A substantial decrease can also be seen in SO2
and PM emissions.
Recommendations for implementing the use of bio diesel cannot be made at this stage as
further studies are necessary to assess existing infrastructure compatible with it.
7. REFERENCES
1. Baumann H.,Tillman A. (2004). The Hitch Hiker’s guide to LCA, Edition 1:7, Studentlitteratur
AB Lund.
2. Nektalova T. (2008). < hypertextbook.com/facts/2006/TatyanaNektalova.shtml> [accessed on 2013.03.08]
3. Altenstedt J. (1998). High and low NOx chemistry in the troposphere, IVL Swedish
Environmental Research Institute: Göteborg.
