1

ENVIRONMENTAL ANALYSIS OF A CONSTRUCTION AND DEMOLI TION 1

WASTE RECYCLING PLANT IN PORTUGAL - PART I: ENERGY 2

CONSUMPTION AND CO 2 EMISSIONS 3

André Coelho1; Jorge de Brito1 4

5

1 Department of Civil Engineering and Architecture, Instituto Superior Técnico, Technical University of 6

Lisbon, Av. Rovisco Pais, 1049-001, Lisbon, Portugal 7

8

Corresponding author: 9

Jorge de Brito, 10 Department of Civil Engineering and Architecture, Instituto Superior Técnico, Technical Uni-11 versity of Lisbon, Av. Rovisco Pais, 1049-001, Lisbon, Portugal. 12 Tel.: +351 218443659, Fax: +351 218443071, E-mail: jb@civil.ist.utl.pt 13

14

ABSTRACT 15

This work is a part of a wider study involving the economic and environmental implica-16

tions of managing construction and demolition waste (CDW), focused on the operation 17

of a large scale CDW recycling plant. This plant, to be operated in the Lisbon Metro-18

politan Area (including the Setúbal peninsula), is analysed for a 60 year period, using 19

primary energy consumption and CO2eq emission impact factors as environmental im-20

pact performance indicators. 21

Simplified estimation methods are used to calculate industrial equipment incorporated, 22

and the operation and transport related impacts. Material recycling - sorted materials 23

sent to other industries, to act as input - is taken into account by discounting the impacts 24

related to industrial processes no longer needed. 25

This first part focuses on calculating the selected impact factors for a base case scenario 26

(with a 350 tonnes/h installed capacity), while a sensitivity analysis is provided in part 27

two. Overall, a 60 year global primary energy consumption of 71.4 thousand toe (tonne 28

2

of oil equivalent) and a total CO2eq emission of 135.4 thousand tonnes are expected. 1

Under this operating regime, around 563 thousand toe and 1465 thousand tonnes CO2eq 2

could be prevented by replacing raw materials in several construction materials indus-3

tries (e.g.: ferrous and non-ferrous metals, plastics, paper and cardboard). 4

5

KEYWORDS 6

Construction and demolition recycling plant, environmental impact, recycling of con-7

struction materials 8

9

3

1. INTRODUCTION 1

Construction industry related issues have been subject to some scrutiny with respect to 2

environmental performance in the past decade. Numerous research works have been 3

published on the environmental life cycle analysis (LCA) of buildings, some of them 4

focusing on the material production stage (Bribián et al., 2011) (Mateus e Bragança, 5

2010) (Thormark, 2000) (Koroneos and Dompros, 2007) (Börjesson and Gustavsson, 6

2000) (González and Navarro, 2006), others on the full construction life cycle 7

(Thormark, 2002) (Kofoworola and Gheewala, 2008) (Peuportier, 2001). 8

Some have intentionally left out the erection and end-of-life cycle stages (Thormark, 9

2006) (Mithraratne and Vale, 2004), since in typical buildings’ LCA these life cycle 10

stages play only a small part in the overall environmental impact (Junnila, 2004). Al-11

though the end-of-life stage has generally been considered in most buildings LCA 12

analysis, only a few authors such as (Blengini, 2009) (Dewulf and et al., 2009) have 13

paid special attention to it. 14

In current buildings with average to high energy demand in operation, as opposed to low 15

energy consumer buildings (Sartori and Hestnes, , 2007) (Thormark, 2002), end-of-life 16

may account for only a small part of the global environmental impact or benefit (generally 17

under 5%). However, depending on the consideration of recycling and its assumed char-18

acteristics (Junnila, 2004) (Blengini, 2009), correctly determining recycling materials’ 19

capacity to replace (thereby displacing part of new materials’ production environmental 20

impacts) and accounting for recycling’s own incorporated impacts (especially due to 21

transporting materials) may change this picture (Dewulf et al., 2009) (Chong and 22

Hermreck, 2010) (Sára et al., 2001). 23

In fact, CDW management networks are vast, complex systems which must be under-24

stood before they can be accounted for in simplified ways in single buildings’ LCAs. 25

Their characteristics are highly region-dependent and involve large numbers of stake-26

4

holders. Specific CDW networks have recently been studied in several research works 1

(Blengini and Garbarino, 2010) (Weil et al., 2006) (Hiete et al., 2011) (Marinković et 2

al., 2010) (Ortiz et al., 2010) (Chong and Hermreck, 2010), all of which apply LCAs or 3

partly evaluate environmental impacts, incorporating impacts from actual demolition 4

activities, material transportation and potential environmental benefits from avoiding 5

the industrial production of construction materials (material substitution). 6

However, the actual place where the primary recycling occurs, the CDW recycling 7

plant, is only briefly considered in these studies, which use general data from local sur-8

veys or from published sources (e.g. Ecoinvent data set). This study attempts to quantify 9

basic environmental impact factors at a fixed large-scale CDW recycling facility. The 10

analysis includes material transportation from generic regional demolition sites, (trans-11

portation) to construction materials’ producers (further processing of secondary raw 12

materials provided by the CDW recycling facility) and to landfill locations (rejected 13

fractions), plant operation and impacts prevented by replacing virgin construction raw 14

materials. These basic environmental impact factors are primary energy consumption 15

and CO2 equivalent emissions, and the analysis uses regional data and actual/possible 16

transportation routes for the CDW facility output material routing. This study is consid-17

ered important if serious intentions exist in recycling CDW in the Lisbon Metropolitan 18

Area. Any further detailing studies, in order to actually design the CDW recycling plant 19

or plants, must undergo the sort of analysis this study has started (in its wider version, 20

including economic and environmental performances, plus respective sensitivity ana-21

lyzes). It also implies important output information useful for policy making regarding 22

CDW management, regional or national-wide. 23

24

2. DESCRIPTION OF THE RECYCLING FACILITY 25

The CDW recycling plant considered can be labelled as Level 3, as suggested in (Sy-26

5

monds Group, 1999). This general classification implies a considerable degree of mecha-1

nization and automation within the facility, intended to be able to receive totally commin-2

gled CDW and extract high purity valuable material fractions, such as concrete aggregates 3

(suitable for concrete production), ceramic aggregates, ferrous and non-ferrous metals 4

(separately), paper and cardboard, plastics, wood and gypsum. The only rejected fluxes 5

are materials contaminated with hazardous substances and wet sludges containing ultra-6

fine mixed particles. Based on (Weihong, 2004), a general flux diagram is presented in 7

Figure 1. 8

The facility is intended to serve the Lisbon Metropolitan area (including the Setúbal 9

peninsula) and was designed to absorb its CDW generation flux, expected to be around 10

416 kg/person/year in 2020 (Coelho and de Brito, 2011). This CDW generation poten-11

tial results in an expected input of 350 tonnes/h for the designed facility, which is lo-12

cated in the Amadora Municipality (Figure 2), after a preliminary study on the minimi-13

sation of transport distance was conducted (Coelho and de Brito, 2013). Location is in 14

fact of primary concern since almost 55% of all the facility's CO2eq emissions in its 15

target operation period of 60 years are due to transportation, for a diesel truck based 16

transportation system. 17

A level 3 CDW recycling facility is expected to make use of plenty of advanced materi-18

als processing equipment. Such equipment was chosen for each function from what was 19

commercially available and designed to handle the amount of material to be processed. 20

Depending on the flux for each process step, one or more identical units were consid-21

ered, in order to meet the required processing demand. A list of this equipment is pre-22

sented in Table 1. 23

The equipment characteristics are mostly the result of a market survey of industrial ma-24

terial processing equipment, thus each power figure is the average of several available 25

machines. This was the procedure whenever more than one suitable item of equipment 26

6

was found (from different suppliers) to fulfil the same function. The facility was as-1

sumed to occupy around a surface area of 27500 m2 (based on (Pereira et al., 2004)) of 2

low environmental value land (brownfield or derelict land), near to road accesses. As 3

for operation, an 8 hours per day, 300 days per year regime was assumed for the CDW 4

recycling plant (Coelho and de Brito, 2013). 5

6

3. ENVIRONMENTAL ANALYSIS 7

As stated in the introduction, the environmental impact factors studied are limited to 8

primary energy consumption and CO2 equivalent emissions. These environmental im-9

pact factors are in fact among the most relevant and have been taken into account in 10

most scientific research on LCA (Ortiz et al., 2009). 11

Operating a CDW recycling facility is, in environmental terms, essentially about using 12

energy, since apart from some noise and dust generation (which are minimised under 13

national and municipal industrial operation regulations), there are no other major self-14

generated environmental impacts. Rejected materials like hazardous contaminated 15

fluxes and wet sludge are only part of the incoming CDW flux that the facility cannot 16

process, which means those materials would have gone to landfill or other processors 17

anyway, had they not entered the CDW recycling facility. Moreover, since it has been 18

demonstrated that around 80% of all emissions into the atmosphere derive from energy 19

production (IEA, 2005), its use and related impacts are indeed the most important envi-20

ronmental issues to be considered. 21

It is believed that if only two environmental impact factors are measured in the present 22

analysis, that does not jeopardize the validity to the conclusions, since, as stated above, 23

most of the known air pollutants are generated by energy production systems (while 24

running a CDW recycling plant is essentially related with energy expenditure). Fur-25

thermore, the aim of the study is to establish a balance between generated and avoided 26

7

impacts - to conclude of the facility's environmental viability - and not to determine 1

absolute impact values, which justifies the simplified approach used. This approach, 2

however, must include estimation of all relevant generated and avoided impacts (on the 3

environmental impact factors used), so that the referred balance may bear some mean-4

ing. 5

6 3.1. Impact factors - incorporated, operation and transport related 7 8 Environmental impacts were considered to be divided into three main categories: incor-9

porated, operation and transportation related. Incorporated impacts are here the primary 10

energy consumed and CO2eq emitted, from raw material extraction to final delivery at 11

the factory gate, for the production of all the machines installed, corresponding to the 12

facility's capacity. These impacts are accounted for each time an item of equipment 13

needs to be replaced, i.e. the initial installation plus all the replacements made over the 14

lifetime were considered (although specific maintenance was not). 15

Operation impacts are essentially linked to electrical energy consumed by operating ma-16

chines (plus a diesel excavator for initial block separation and size reduction), which are 17

considered constant for all operating hours. This will constitute an upper limit for opera-18

tional energy demand, since some apparatus can be adjusted (manually or automatically) 19

to lower input, thereby reducing its electricity demand for different material input feeds. 20

Finally, transportation needs directly linked to the facility's operation (although not nec-21

essarily organised and paid for by its management) comprise current truck journeys 22

from regional demolition sites, from the plant’s location to i) the nearest available land-23

fill (for the rejected material fraction) and to ii) the secondary material processors or 24

industries which receive the CDW recycling plant output materials for their own indus-25

trial processes. 26

3.1.1 Incorporated impacts 27 28

8

Incorporated primary energy consumption and CO2eq emissions were calculated in a 1

simplified way, assuming all apparatus/machine weight to be steel, except for spirals, 2

which are mainly fibreglass, and the human operator cabin, assumed to contain a mixed 3

steel-concrete slab (floor) and light steel-sheet polyurethane insulated sandwich panels 4

for roof and walls. Weight data is averaged from the equipment manufacturers con-5

sulted and incorporated primary energy consumption and CO2eq emitted unit values 6

(per kg of equipment material produced) were taken from ICEv2.0 (Geoff and Craig, 7

2011). Table 2 summarises all the data compiled and used in the incorporated impacts 8

calculation, for each item of apparatus. Although enhancements in production method 9

efficiency and the use of increasing percentages of recycled content and renewable en-10

ergies may occur in the CDW recycling facility during its 60-year operating life, which 11

would lower the incorporated environmental impact in replacement activities, only to-12

day’s figures were considered (considered constant throughout the operating period). 13

14 3.1.2 Operation impacts 15

16 Electrical devices, such as the vibrating feeder, draw energy from the electrical supply 17

network in proportional to their power rating. Partial load factors or stepped demand-18

dependent electrical motors, which might reduce electricity demand by some equipment 19

at given times, are not accounted for in this study. Energy consumption is calculated by 20

simply multiplying this power rating by the operating hours of each apparatus, which 21

depends on the facility's own operating schedule and the time spent on full or partial 22

mode operation. 23

Full operation occurs when input CDW is commingled (considered, for this base case, 24

to be 70% of all operating hours) and partial mode when CDW input is separated (only 25

aggregates, essentially concrete and ceramics). Final electricity demand, in kWh, is 26

converted to primary energy in kgoe using a conversion coefficient of 0.29, which is 27

officially used by the thermal regulations for buildings in Portugal (RSECE, 2006). 28

9

CO2eq emission per kgoe unit of primary electricity generation is estimated using an-1

other conversion factor, 1.2 (kgCO2eq/kgoe), which is formally stated and used regu-2

larly in (buildings) energy certification in Portugal (Rodrigues et al., 2009). For the ex-3

cavator, a diesel powered machine, a final energy/primary energy conversion factor of 4

0.086 (kgoe/kWh) (RSECE, 2006), and a specific CO2eq emission factor of 3.032 5

kgCO2eq/kgoe were considered (Lobo, 2009). Table 3 shows the internal equipment 6

(primary) energy use and related impacts, summarised by equipment item, for one year. 7

8 3.1.3 Transport related impacts 9

10 Transportation within a CDW recycling plant is divided into three main categories: 11

routes from construction/demolition/retrofit sites to the plant; routes from the plant to 12

recycled materials processors (for direct use in new products fabrication or further 13

treatment for recycling purposes), and routes from the plant to landfills (or further 14

treatment processors for final disposal purposes). Transportation of materials from con-15

struction, demolition or retrofit sites is considered in a simplified way by assuming an 16

overall average distance of 21 km, with the CDW recycling plant being located in 17

Amadora. This distance was arrived at by listing the distance between the geometric cen-18

tres of all metropolitan Lisbon municipalities and the Amadora municipality centre (based 19

on the map in Figure 2) and calculating a weighted average over the estimated mass of 20

CDW generation for these municipalities (Coelho and de Brito, 2013). 21

Assuming a constant transportation rate of 350 tonnes/h (the plant's capacity), the an-22

nual rate of CDW entering the facility will be 840000 tonnes/year. With a standard 19.3 23

m3 truck for all freight and an average CDW density of 1400 kg/m3 (commingled 24

CDW), than the average volume transported from external sites is 600000 m3/year, 25

which is around 653000 km travelled/year. Using a diesel consumption figure of 0.249 26

kg/vkm ("v" stands for "vehicle") (Spielmann et al., 2007), which convert to 0.26 27

10

kgoe/vkm, annual primary energy consumption due to this transportation portion 1

amounts to 169200 kgoe/year. 2

This transportation need generates about 545500 kg CO2eq emissions per year, using a 3

factor of 0.835 kg CO2eq/vkm. This latter factor is derived from the original figure of 4

0.7882 kg CO2/vkm of direct CO2 emissions, taken from the EcoInvent database 5

(Spielmann et al., 2007), multiplied by 1.06, to convert direct CO2 emissions into CO2 6

equivalent emissions (as considered by ICEv2.0) (Geoff and Craig, 2011). 7

Transportation of rejected materials from the CDW recycling facility is also calculated 8

in a simplified way, considering an average plant-to-landfill distance of 42 km 9

(Lourenço, 2007). Totalling the amount of material rejected each year, in this case 10

123400 tonnes/year, and assuming the same standard truck is used, a total of 191600 11

km/year are expected, which relates to extra 160000 kg CO2eq/year, using the same 12

factors as before. When it came to routing output materials to other material processors 13

or to direct producers, a matrix of possible destinations was compiled which took into 14

account the facility's location and the destinations available for each material (Table 4). 15

From this quantification, a total 625000 km/year are expected, which translates into 16

162000 kgoe/year of primary energy demand and 522200 kgCO2eq/year of emissions. 17

18 3.2. Impact factors - impacts prevented by recycling 19 20 The CDW recycling facility is mostly an industrial facility that guarantees the transforma-21

tion of commingled CDW into secondary raw materials, suitable to be used as input in other 22

industries’ processes. Its purpose is thus to separate the CDW to acceptable purity standards 23

so that materials are accepted by these other industries and are actually recycled. 24

Every tonne of the CDW recycling facility output that is actually recycled will displace 25

not only an equivalent amount of primary (natural) raw materials but its whole embod-26

ied industrial process too. For this specific case, all the (CDW recycling facility) output 27

11

materials’ possible industrial recycling routes were analysed to try and estimate the pre-1

vented primary energy consumption and CO2eq emissions each implied. 2

The product industry's prevented environmental impacts - in this case primary energy con-3

sumption and CO2eq emissions - were considered proportional to the percentage of end-use 4

energy that can be prevented by incoming secondary raw materials, as shown in Table 5. 5

For example, only 23.7% of the impacts of wood particleboard and fibreboard production 6

are prevented by using recycled materials, since over 70% of the energy end-use is concen-7

trated in the final stage of its production, which does not depend on the materials’ origin. 8

As for the other CDW recycling facility output materials, in particular heavy metals 9

(mainly mercury and nickel), concrete and ceramic aggregates and plastics, it was con-10

cluded from the analysis of the relevant industrial process that the recycled input mate-11

rials would roughly replace all related industrial energy use (and therefore, within the 12

approximation considered, primary energy consumption and CO2eq. emissions). Table 6 13

was composed from these estimations plus further data from ICEv2.0 (Geoff and Craig, 14

2011) and (Weil et al., 2006). 15

16

4. RESULTS AND DISCUSSION 17

60-year operating results for primary energy consumption and CO2eq emissions are 18

given in Figure 3 and Figure 4. Yearly and 60-year total results for primary energy con-19

sumption and CO2eq emissions are provided in Table 7. Table 8 contains the aggregated 20

results, showing impacts per general activity, i.e. for installation (incorporated impacts), 21

operation and transportation. As expected, because the annual primary energy consump-22

tion and CO2eq emissions were assumed to be constant, Figure 3 and Figure 4 show 23

straight lines, with the ‘prevented impact’ lines starting from zero, while the impact 24

lines start from a non-zero point. These initial quantities correspond to the incorporated 25

12

impacts, namely 220000 kgoe of primary energy consumption and 644000 kg CO2eq 1

emissions. 2

Assuming this linear trend over an anticipated 60 years of CDW recycling facility operat-3

ing time, these figures clearly show that the prevented impacts dwarf the produced im-4

pacts. In fact, the prevented/produced impacts relationship is as presented in Table 7: 7.9 5

with respect to primary energy consumption and as much as 10.8 for CO2eq emissions. 6

The magnitude of this difference is explained by the nature of some of the industrial 7

processes prevented by using recycled materials as input, because they have high energy 8

consumption and carbon emissions. For example, even considering that concrete and 9

ceramic aggregate represent around 95% of all output materials’ mass, the fact that the 10

primary energy consumption prevented in producing ferrous metals is about 221 times 11

higher per mass unit than producing coarse concrete aggregates (or 3800 times higher 12

when producing aluminium), is enough to exceed the plant's own produced impacts (in-13

cluding installation, operation and transport). Although analysing only avoided impacts 14

due to the replacement of steel and natural aggregates virgin materials supply, also 15

(Blengini and Garbarino, 2010) reaches a similar conclusion; in this latter case, it was 16

concluded that transportation would have to increase by a factor of two or three before 17

the produced impacts would surpass the avoided ones. Also (Dewulf et al., 2009) is in 18

line with this result (in a general sense), when it states that a best overall scenario for the 19

end-of-life stage of a dwelling (which involves recycling of aggregates, metals and 20

glass) can save as much as three times the resources necessary for the disposal scenario 21

(only collection and transportation to landfill). 22

As for general activity impact distribution, Table 8 shows that the greatest primary en-23

ergy consumption arises from the plant’s operation (67%), while transportation accounts 24

for the highest share of CO2eq emissions (54%), over the 60 years. Although not di-25

rectly comparable, primary energy consumption in transportation (kgoe/vkm) and 26

13

plant's operation (kgoe/h) generate CO2eq emissions which are clearly more prominent 1

in transportation than in operation. 2

This is surely linked to the fact that, per unit of primary energy consumed, diesel burned 3

in internal combustion engines is around 2.5 times more carbon intense than the average 4

Portuguese electricity production mix (comparing the figures in kgCO2eq/kgoe pre-5

sented in 3.1.2). In both impact categories, however, incorporated impacts are very-6

small-to-negligible (under 2% of global calculated impacts), considering all equipment 7

replacement necessary for 60 years. 8

Due to their high energy intensity, both in operation and associated transportation, this 9

kind of industrial facility has much lower incorporated impact shares (total impacts over 10

the life-cycle) than buildings have. Incorporated energy use shares are often of the order 11

5-15% for conventional buildings, and up to 40-60% for low-energy use buildings 12

(Thormark, 2006). 13

Comparing this case to other waste treatment systems, in particular with respect to mu-14

nicipal solid waste (MSW), it is interesting to observe that there is a very significant 15

increase in the overall reduction of primary energy consumption and CO2eq emissions 16

(Table 9). In fact, for a similar recycling share (84%) the CDW recycling plant de-17

scribed in this study is able to save one order of magnitude more CO2eq than an MSW 18

treatment/recycling scheme, per processed mass unit. Figures in Table 9 are presented 19

per tonne of processed material, which is considered an adequate common functional 20

unit in these waste processing industrial facilities. However, and in order to establish a 21

proper comparison, recycling rates between facilities must be similar, since this consid-22

erably affects avoided impacts; consequently, comparison figures calculated (as for 23

CO2eq. and primary energy consumption factors) are referred to MSW facility consid-24

ered in (De Feo and Malvano, 2009) (80% of mass sent for recycling). 25

14

With respect to primary energy consumption, the total prevented quantity can amount to 1

more than 5 times that of an MSW plant network. This may be linked to the fact that 2

processed materials in the CDW recycling plant are much denser on average than those 3

at MSW treatment/recycling plants. While the average mixed CDW density can be 4

taken as 1400 kg/m3 (Construction Materials Recycler), a reasonable estimate for mixed 5

MSW is around 150 kg/m3 (State Government Victoria). 6

This means that the MSW treatment/recycling scheme will need to consume more pri-7

mary energy, and therefore emit a much higher proportion of CO2eq for each processed 8

mass unit (in other words, it must process - at the expense of more energy consumption 9

and CO2eq. emission - much higher volumes of waste for the same tonnage of waste). 10

This further emphasises the environmental relevance of recycling CDW, though this 11

does not mean that the recycling of appropriate fractions of MSW can be disregarded or 12

considered low priority. 13

14

5. CONCLUSIONS 15

A simplified environmental impact assessment was carried out that targeted the installa-16

tion, operation and transport related needs of a large Level 3 CDW recycling plant. 17

The results are simplified, in terms of impact factors chosen and analysed, because they 18

were reduced to primary energy use and CO2eq emissions. But these are regarded as the 19

most important environmental aspects to be determined in current industrial systems. 20

Other simplifications were considered, such as construction/retrofit sites’ distance to the 21

CDW recycling facility and the electricity consumption of installed equipment, which was 22

assumed to be constant, derived directly from their rated (electric) power. Furthermore, 23

incorporated impacts were swiftly calculated from the nominal weight of each apparatus, 24

assuming it was made from only one dominant material (steel, fibreglass, concrete). 25

15

From this analysis of the 350 tonnes/h CDW recycling facility, for a 60-year operating 1

period and its specific installation conditions (including location), the following conclu-2

sions can be drawn: 3

- The environmental benefits of installing this CDW recycling plant are considerable. 4

Impacts prevented due to raw (virgin) material replacement in construction products 5

industries are over 10 times those generated in terms of CO2eq emissions, and as much 6

as 8 times for primary energy consumption; 7

- Overall CO2eq emissions generated by facility use (over a 60-year period) are domi-8

nated by transportation needs (54%). This means that considerable effort must be made 9

to reduce the CO2eq emission intensity of the transportation network which at present 10

mainly uses diesel fuel. From the building/demolition sites to the recycling facility the 11

transportation network is highly dispersed around companies (contractors and special-12

ised transportation firms, for hundreds of different sites), which makes it difficult to 13

centrally optimise the transportation system and change the fuel used. However, trans-14

portation from the CDW recycling facility to landfills and other industries (for material 15

recycling) can be secured by a centralised truck fleet, which can be converted into elec-16

tric vehicles; there are already some heavy duty electric vehicle suppliers in the market, 17

and the main producers are prototyping; 18

- Incorporated impacts, resulting from equipment installation and its lifetime replace-19

ment (over 60 years), are negligible compared to total impacts (incorporated, operation 20

and associated transport needs); 21

- This kind of CDW recycling facility has greater primary energy and CO2eq emission 22

savings than other waste processing networks, notably MSW, per processed mass unit. 23

CO2eq overall balance can be up to 10 times greater (in savings) than an equivalent re-24

cycled output percentage from an MSW treatment process, and 5 times greater in terms 25

of primary energy consumption. 26

16

1

6. ACKNOWLEDGEMENTS 2

Thanks are due to the FCT (Foundation for Science and Technology) for the research 3

grant awarded to the first author and to the ICIST - IST research centre. 4

5

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2

22

FIGURE CAPTIONS 1

Figure 1 - General layout sequence for the CDW recycling plan 2

Figure 2 - Straight line connection between the CDW recycling facility location and 3

rough geometrical centres of Lisbon statistical regions’ municipalities 4

Figure 3 - CDW recycling facility total primary energy consumption vs. prevented pri-5

mary energy consumption (due to replaced industrial processes) 6

Figure 4 - CDW recycling facility total CO2eq emissions vs. prevented CO2eq emis-7

sions (due to replaced industrial processes) 8

9

23

Input

conveyor

MetalsPaper

PlasticsWood conveyor

conveyor

PaperPlastics

Woodconveyor

copperlead conveyor conveyor

cobaltmercury

wet sludges

gypsum

concrete aggregates

Ceramic fines

Density separatorAir jig

concrete + sand fines

Size separation

Vibrating feederManual separation (>80mm)

Magnetic separation

Breaking acessories as hydraulic hammer and scissors

Ferrous metals

Air separation Air siftersMetals separation Eddy current

Crushing plantMagnetCrusher

Size separationHorizontal screens (dry) (>40mm; <40mm)

Large volume material separation - Excavator

Visual inspection

Non-ferrous metals

Size separation

Fines separationSpirals (wet)

Weighting

Scales

Ceramic aggregates

Density separatorAir jig

Horizontal screens (dry) (>4mm; <4mm)

Spirals (wet)Heavy metals separation

Loads contaminated with potencially

hazardous materials

< 4mm > 4mmc

1

Figure 1 - General layout sequence for the CDW recycling plan (Coelho and de Brito, 2 2013) 3

4

24

1

Figure 2 - Straight line connection between the CDW recycling facility location and 2 rough geometrical centres of Lisbon statistical regions’ municipalities (Coelho and de 3 Brito, 2013) 4

5

25

0.0E+00

1.0E+08

2.0E+08

3.0E+08

4.0E+08

5.0E+08

6.0E+08

0 5 10 15 20 25 30 35 40 45 50 55 60

Acc

umul

ated

prim

ary

ener

gy

cons

ump

tion,

kg

oe

Years

Primary energy consumption -

CDW recycling facility

Avoided primary energy

consumption

1

Figure 3 - CDW recycling facility total primary energy consumption vs. prevented pri-2 mary energy consumption (due to replaced industrial processes) 3

4

0.0E+00

2.0E+08

4.0E+08

6.0E+08

8.0E+08

1.0E+09

1.2E+09

1.4E+09

1.6E+09

0 5 10 15 20 25 30 35 40 45 50 55 60

Acc

umul

ated

CO

2eq

. em

issi

ons

, kg

CO

2 eq

.

Years

CO2eq. emissions - CDW

recycling facility

CO2eq. avoided emissions

5

Figure 4 - CDW recycling facility total CO2eq emissions vs. prevented CO2eq emissions 6 (due to replaced industrial processes) 7

8

26

TABLE CAPTIONS 1

Table 1 - Main attributes of equipment considered for the 350 tonnes/h CDW recycling 2

facility 3

Table 2 - CDW recycling plant equipment: incorporated environmental impact 4

quantification 5

Table 3 - CDW recycling plant equipment: operational environmental impact 6

quantification 7

Table 4 - Transportation needs for routing the CDW recycling facility output materials 8

Table 5 - End-use energy consumption profile for the main stages in several product 9

industries (kWh/ton) 10

Table 6 - Prevented environmental impacts due to virgin raw material replacement by 11

recycled materials input in several industries 12

Table 7 - Initial, yearly and 60-year total primary energy consumption and CO2eq emis-13

sion results for the CDW recycling facility 14

Table 8 - CDW recycling facility’s 60-year primary energy consumption and CO2eq 15

emissions per activity 16

Table 9 - Comparison between waste treatment processes - primary energy consumption 17

and CO2eq emissions 18

19

27

Table 1 - Main attributes of equipment considered for the 350 tonnes/h CDW recycling 1 facility 2

Equipment (each unit) Capacity, tonnes/h

Power, kW Energy source Average useful

life, years Number of items required in the 350tonnes/h facility

Scales - 0.05 Electricity 30 1

Excavator - 90 Diesel 20 1

Vibrating feeder 335 16.2 Electricity 8 1

Magnet (ferrous metals) 350 6.5 Electricity 15 1

Manual separation cabinet 62 0.28 Electricity 30 1

Crusher 238 110 Electricity 10 1

Horizontal screen 1 300 18.5 Electricity 6 1

Air sifter 100 6.3 Electricity 20 3 Eddy current generator (non-ferrous metals) 350 16.4 Electricity 15 1

Horizontal screen 2 300 22.3 Electricity 6 1

Air jig 30 126.7 Electricity 20 6

Spirals 40 27.0 Electricity 15 7

Conveyors 5m 300 5.4 Electricity 20 2

Conveyors 10m 300 10.8 Electricity 20 3

Conveyors 15m 300 16.3 Electricity 20 1 Notes: 3 - Further details on this data can be found in (Coelho and de Brito, 2013)Erro! A origem da referência não foi 4 encontrada.. 5

6

28

Table 2 - CDW recycling plant equipment: incorporated environmental impact quantifi-1 cation 2

Equipment Average weight, kg/unit

Equipment made of (mate-rial) (c)

Primary energy con-sumption, kWh/unit

CO2eq emission, kgCO2eq/unit

Scales 8 825 Steel (section) 62 315 15 709

Excavator 20 315 Steel (section) 143 448 36 161

Vibrating feeder 4 466 Steel (section) 31 537 7 950

Magnet (ferrous metals) 4 458 Steel (section) 31 479 7 935

Manual separation cabinet

(a) Steel sheet, concrete and polyurethane foam

35 830 11 770

Crusher 35 775 Steel (section) 252 614 63 680

Horizontal screen 1 5 657 Steel (section) 39 943 10 069

Air sifter 1 190 Steel (sheet) 12 902 3 356 Eddy current generator (non-ferrous metals) 2 406 Steel (section) 16 989 4 283

Horizontal screen 2 7 341 Steel (section) 51 839 13 068

Air jig 40 000 Steel (section) 282 448 71 200

Spirals (b) 1 029 Fibreglass 6 720 1 306

Conveyors 5m 1 295 Steel (section) 9 146 2 305

Conveyors 10m 2 307 Steel (section) 16 293 4 107

Conveyors 15m 3 320 Steel (section) 23 441 11 770 Notes: 3 (a) Environmental impact factors determined per m2, based on figures from (ITEC, 2011). 4 (b) One group module of 23 individual spirals. 5 (c) Although the items of equipment are composed of many other materials, for simplicity’s sake it is considered that 6 they are made only of the listed material (which in fact accounts for most of its mass in weight). 7

8

29

Table 3 - CDW recycling plant equipment: operational environmental impact quantifi-1 cation 2

Equipment Power, kW/unit

Energy utilised

Primary energy con-sumption, kgoe/year (a)

CO2eq emission, kgCO2eq/year (a)

Scales 0.05 Electricity 35 42

Excavator 90 Diesel 18 576 56 322

Vibrating feeder 16.2 Electricity 11 275 13 530

Magnet (ferrous metals) 6.5 Electricity 4 524 5 429

Manual separation cabinet 0.28 Electricity 136 164

Crusher 110 Electricity 76 560 91 872

Horizontal screen 1 18.5 Electricity 12 876 15 451

Air sifter 6.3 Electricity 9 135 10 962

Eddy current generator (non-ferrous metals) 16.4 Electricity 7 990 9 588

Horizontal screen 2 22.3 Electricity 15 544 18 653

Air jig 127 Electricity 476 189 571 427

Spirals 27 Electricity 114 631 137 557

Conveyors Variable Electricity 49 010 58 812 Notes: 3 (a) All installed units. 4

5

30

Table 4 - Transportation needs for routing the CDW recycling facility output materials 1

Materials Possible destina-tion (companies)

Distance from Amadora geome-trical centre, km

Transported weight, ton-nes/year

Transported volume, m3

Freight number

Total dis-tance trans-ported, km

Ferrous metals

Ecometais

32 14 051 10 036 519 16 623

Non-ferrous metals (mainly aluminium)

32 37 26 1 44

Heavy metals 32 301 215 11 357

Concrete aggregate (coarse)

Betecna - Oeiras 22.7 36 626 26 161 1 354 30 738 Betão Liz - Carna-xide

7.8 36 626 26 161 1 354 10 562

Camilo & Lopez - Moita

41 36 626 26 161 1 354 55 518

Camilo & Lopez - Montijo

39 36 626 26 161 1 354 52 810

Concrete aggregate (fine)

Betecna - Oeiras 22.7 48 760 34 829 1 803 40 922

Betão Liz - Carna-xide

7.8 48 760 34 829 1 803 14 061

Camilo & Lopez - Moita

41 48 760 34 829 1 803 73 912

Camilo & Lopez - Montijo

39 48 760 34 829 1 803 70 307

Ceramic aggregates (coarse) Generic use in

roadwork

21 (a) 133 985 95 703 4 954 104 141

Ceramic aggregates (fine)

21 (a) 178 749 127 678 6 609 138 934

Paper and cardboard Portucel, Setúbal 63 3 502 2 501 129 8 156

Plastics Revolta 7 600 429 22 155

Wood Revolta 7 9 546 6 819 353 2 471

Renascimento 15 9 546 6 819 353 5 294 Notes: 2 (a) Since it is impossible to know where most of the aggregates will be placed in the Lisbon Metropolitan region, the 3 same average of 21 km is assumed, as described in 3.1.3. 4

5

31

Table 5 - End-use energy consumption profile for the main stages in several product 1 industries (kWh/ton) 2

Product industry

Industrial stage Percentage of end-use energy avoided if incoming secon-dary raw materials are used, %

Extraction to the factory gate Final production Process

Transportation (d)

Boat (transocean tanker) Freight train Truck

Wood particleboard and fibreboard (a)

269.1 0.0 18.0 618.7 2913 23.7

Paper and cardboard (b) 75.8 0.0 5.28 484.7 401.2 58.5

Aluminium (c) 2195 135.1 9.01 1290 1039 77.7

Iron and steel (c) 161.9 82.3 18.2 6.03 694.9 27.9 Notes: 3 (a) Source data from Ecoinvent database (Werner et al., 2007). 4 (b) Source data from Ecoinvent database (Hischier, 2007). 5 (c) Source data from Ecoinvent database (Classen et al., 2009). 6 (d) Source data from Ecoinvent database - Transportation (Spielmann et al., 2007) and Fuel (Dones et al., 2007). 7

8

32

Table 6 - Prevented environmental impacts due to virgin raw material replacement by 1 recycled materials input in several industries 2

CDW recycling facil-ity output material

Replaced portion of the industrial process

Virgin raw material to be replaced

Industrial processes: prevented energy and CO2 emissions Source

reference Primary energy Emissions

kWh/ton kgoe/ton kgCO2eq./ton

Ferrous metals

From extrac-tion to final stage input (a)

Iron ore 2740 236 805

(Geoff and Craig, 2011)

Non-ferrous metals (mainly aluminium) Bauxite ore 47083 4048 9944

Heavy metals Ores of

Mercury 24169 2078 5236

Nickel 45559 3917 13144

Cadmium - - - -

Concrete aggregates (coarse)

From extrac-tion to the factory output gate (b)

Limestone crushed aggregates 12.39 1.07 3.1

(Weil et al., 2006)

Concrete aggregates (fine)

Ceramic aggregates (coarse) (c)

River/sea sand 9.58 0.82 2.2 Ceramic aggregates (fine) (c)

Paper and cardboard From extrac-tion to the factory input gate

Cellulose (e) 5452 469 862

(Geoff and Craig, 2011)

Plastics Oil derivatives 22363 1923 3310

Wood Wood particleboard and fibreboard (d) 972 84 168

Notes: 3 (a) For ferrous and non-ferrous metals, the replaced industrial processes include: agglomeration and fusion (steel 4 production); oxidation and primary alumina precipitation and dewatering (aluminium production). 5 (b) All recycled aggregate at the plant gate can replace the whole extraction and production stages (of natural aggre-6 gates), up to the ready-mixed concrete facility’s gate. 7 (c) Resulting from estimated demand for base filling needs in the Metropolitan Lisbon Area (Coelho and de Brito, J., 8 2013), it has been concluded that the quantity is enough to absorb all ceramic aggregate output from the CDW recy-9 cling facility. Consequently, although these recycled ceramic aggregates could have other uses, e.g. direct input into 10 ceramic brick production, only replacement of crushed limestone aggregates and river/sea sand was considered here. 11 (d) Although the range of applications for recycled wood chips is larger - wood particleboard and fibreboard, animal 12 bedding, composting and incineration - the potential demand for wood chips to produce particleboard and fibreboard 13 is enough to absorb all the CDW recycling plant’s output. As a consequence, only this last industrial process was 14 targeted for replacement. 15 (e) Only the wood extraction, production and transport processes are prevented. 16

17

33

Table 7 - Initial, yearly and 60-year total primary energy consumption and CO2eq emis-1 sion results for the CDW recycling facility 2

Energy consumption/emissions

Embodied primary energy, first year, kgoe 219 547 Operation primary energy, kgoe/year 796 482 Transport primary energy, kgoe/year 380 889

Incorporated CO2eq, first year, kgCO2eq 643 984 Operation CO2eq, kgCO2eq/year 989 810 Transport CO2eq, kgCO2eq/year 1 227 727

Prevented energy consumption/prevented emissions

Primary energy prevented, kgoe/year 9 377 041 CO2eq prevented, kgCO2eq/year 24 421 183

60-year overall results

Total primary energy consumption, kgoe 71 430 578 Total CO2eq emission, kgCO2eq 135 357 575 Total primary energy prevented consumption, kgoe 562 622 431 Total CO2eq prevented emission, kgCO2eq 1 465 270 986 Total prevented primary energy/total consumption 7.9 Total prevented CO2eq emissions/total emitted 10.8

3 4

34

Table 8 - CDW recycling facility’s 60-year primary energy consumption and CO2eq 1 emissions per activity 2

Impact activity Primary energy consumption CO2eq. emission

toe x 1000 % Tonnes CO2eq x 1000 %

Incorporated 0.80 1.12 2.31 1.71

Operation 47.8 66.9 59.4 43.9

Transportation 22.9 32.0 73.7 54.4

All activity 71.4 100 135.4 100 3

4

35

1

Table 9 - Comparison between waste treatment processes - primary energy consumption 2 and CO2eq emissions 3

Waste treatment system Global unit impacts (a)

% of mass sent for recycling Primary energy consumption CO2eq emission

kgoe/ton kgCO2eq/ton

CDW recycling plant -584.7 -1583 84

MSW treatment in Bologna (b) -87.1 -27.0 28

MSW treatment in Avellino (c) -115.0 -155.2 80 Notes: 4 (a) Figures per tonne of processed material, including prevented impacts. 5 (b) (Buttol et al., 2007) 6 (c) (De Feo and Malvano, 2009) 7