1

ENVIRONMENTAL ANALYSIS OF A CONSTRUCTION AND DEMOLITION

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WASTE RECYCLING PLANT IN PORTUGAL - PART I: ENERGY

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CONSUMPTION AND CO2 EMISSIONS

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André Coelho1; Jorge de Brito1

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

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

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Corresponding author: Jorge de Brito, Department of Civil Engineering and Architecture, Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001, Lisbon, Portugal. Tel.: +351 218443659, Fax: +351 218443071, E-mail: [email protected]

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ABSTRACT

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

17

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

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

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itan Area (including the Setúbal peninsula), is analysed for a 60 year period, using pri-

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mary energy consumption and CO2eq emission impact factors as environmental impact

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performance indicators.

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Simplified estimation methods are used to calculate industrial equipment incorporated,

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

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

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related to industrial processes no longer needed.

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

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

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

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1

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

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

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

4

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

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KEYWORDS

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

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struction materials

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2

1

1.

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

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

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

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

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

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

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mark, 2002) (Kofoworola and Gheewala, 2008) (Peuportier, 2001).

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

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

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

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hough the end-of-life stage has generally been considered in most buildings LCA analy-

13

sis, only a few authors such as (Blengini, 2009) (Dewulf and et al., 2009) have paid spe-

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cial attention to it.

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

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

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

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

19

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

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

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

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

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Hermreck, 2010) (Sára et al., 2001).

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

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

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Their characteristics are highly region-dependent and involve large numbers of stake3

INTRODUCTION

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

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

3

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

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partly evaluate environmental impacts, incorporating impacts from actual demolition

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activities, material transportation and potential environmental benefits from avoiding

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the industrial production of construction materials (material substitution).

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

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

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

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

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

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

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

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

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materials. These basic environmental impact factors are primary energy consumption

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

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

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ered important to implement recycling CDW in the Lisbon Metropolitan Area. Any fur-

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ther detailing studies, in order to actually design the CDW recycling plant or plants,

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

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economic and environmental performances, plus corresponding sensitivity analyses). It

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also yields important output information useful for policy-making regarding CDW

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management, at regional or national level. The methodology used and the results ob-

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tained can be used to replicate this type of study in any other region of the world, with

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adaptations to take into account local laws and construction practice.

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2.

DESCRIPTION OF THE RECYCLING FACILITY

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The CDW recycling plant considered can be labelled as Level 3, as suggested in (Symonds

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Group, 1999). This general classification implies a considerable degree of mechanization

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and automation within the facility, intended to be able to receive totally commingled CDW

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and extract high purity valuable material fractions, such as concrete aggregates (suitable for

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concrete production), ceramic aggregates, ferrous and non-ferrous metals (separately), pa-

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per and cardboard, plastics, wood and gypsum. The only rejected fluxes are materials con-

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taminated with hazardous substances and wet sludges containing ultra-fine mixed particles.

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Based on (Weihong, 2004), a general flux diagram is presented in Figure 1. Insert Figure 1

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

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

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

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

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ed in the Amadora Municipality (Figure 2), after a preliminary study on the minimisa-

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

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

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operation period of 60 years are due to transportation, for a diesel truck based transpor-

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tation system.

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Insert Figure 2

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

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

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

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

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

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sented in Table 1. 5

1

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

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

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

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

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

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

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

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recycling plant (Coelho and de Brito, 2013). Insert Table 1

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3.

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

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

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

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

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

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

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

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generated environmental impacts. Rejected materials like hazardous contaminated flux-

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es and wet sludge are only part of the incoming CDW flux that the facility cannot pro-

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cess, which means those materials would have gone to landfill or other processors any-

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

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

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

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ronmental issues to be considered.

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It is believed that if only two environmental impact factors are measured in the present 6

ENVIRONMENTAL ANALYSIS

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

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

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ning a CDW recycling plant is essentially related with energy expenditure). Furthermore,

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the aim of the study is to establish a balance between generated and avoided impacts - to

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conclude of the facility's environmental viability - and not to determine absolute impact

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values, which justifies the simplified approach used. This approach, however, must in-

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clude estimation of all relevant generated and avoided impacts (on the environmental im-

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pact factors used), so that the referred balance may bear some meaning.

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

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

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

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

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

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

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lifetime were considered (although specific maintenance was not).

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

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

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

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

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

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

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sarily organised and paid for by its management) comprise current truck journeys from re-

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gional demolition sites, from the plant’s location to i) the nearest available landfill (for the

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rejected material fraction) and to ii) the secondary material processors or industries which

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receive the CDW recycling plant output materials for their own industrial processes. 7

3.1.1 Incorporated impacts

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Incorporated primary energy consumption and CO2eq emissions were calculated in a

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

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

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

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

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ed and incorporated primary energy consumption and CO2eq emitted unit values (per kg

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of equipment material produced) were taken from ICEv2.0 (Geoff and Craig, 2011).

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Table 2 summarises all the data compiled and used in the incorporated impacts calcula-

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tion, for each item of apparatus. Although enhancements in production method efficien-

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cy and the use of increasing percentages of recycled content and renewable energies

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

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lower the incorporated environmental impact in replacement activities, only today’s

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figures were considered (considered constant throughout the operating period). Insert Table 2

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Electrical devices, such as the vibrating feeder, draw energy from the electrical supply net-

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

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

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

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ly multiplying this power rating by the operating hours of each apparatus, which depends on

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the facility's own operating schedule and the time spent on full or partial mode operation.

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

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

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

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

3.1.2 Operation impacts

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

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

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

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ly in (buildings) energy certification in Portugal (Rodrigues et al., 2009). For the exca-

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

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

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

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

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Insert Table 3

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

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

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

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

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

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

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

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dora. This distance was arrived at by listing the distance between the geometric centres of

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all metropolitan Lisbon municipalities and the Amadora municipality centre (based on the

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

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

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

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

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

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

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

3.1.3 Transport related impacts

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

2

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

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amounts to 169200 kgoe/year.

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

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

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

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

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

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

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

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ço, 2007). Totalling the amount of material rejected each year, in this case 123400

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

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are expected, which relates to extra 160000 kg CO2eq/year, using the same factors as

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before. When it came to routing output materials to other material processors or to di-

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rect producers, a matrix of possible destinations was compiled which took into account

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

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this quantification, a total 625000 km/year are expected, which translates into 162000

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kgoe/year of primary energy demand and 522200 kgCO2eq/year of emissions. Insert Table 4

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3.2. Impact factors - impacts prevented by recycling The CDW recycling facility is mostly an industrial facility that guarantees the transfor-

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mation of commingled CDW into secondary raw materials, suitable to be used as input in

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

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

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

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not only an equivalent amount of primary (natural) raw materials but its whole embod10

1

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

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

3

vented primary energy consumption and CO2eq emissions each implied.

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

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

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

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

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

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trated in the final stage of its production, which does not depend on the materials’ origin. Insert Table 5

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

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

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

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

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

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

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2011) and (Weil et al., 2006). Insert Table 6

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4.

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

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in Figure 3 and Figure 4. Yearly and 60-year total results for primary energy consumption

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and CO2eq emissions are provided in Table 7. Table 8 contains the aggregated results,

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

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and transportation. As expected, because the annual primary energy consumption and

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CO2eq emissions were assumed to be constant, Figure 3 and Figure 4 show straight lines, 11

RESULTS AND DISCUSSION

1

with the ‘prevented impact’ lines starting from zero, while the impact lines start from a

2

non-zero point. These initial quantities correspond to the incorporated impacts, namely

3

220000 kgoe of primary energy consumption and 644000 kg CO2eq emissions.

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Insert Figure 3

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Insert Figure 4

6

Insert Table 7

7

Insert Table 8

8

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

9

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

10

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

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

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

13

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

14

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

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

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

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

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

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

20

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

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and Garbarino (2010) reach a similar conclusion; in their case, it was concluded that

22

transportation would have to increase by a factor of two or three before the produced

23

impacts would top the avoided ones. Dewulf et al. (2009) are also in line with this result

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(in a general sense), when they state that the best overall scenario for the end-of-life

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stage of a dwelling (which involves recycling of aggregates, metals and glass) can save

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as much as three times the resources necessary for the disposal scenario (only collection 12

1

and transportation to landfill).

2

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

3

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

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

5

ly comparable, primary energy consumption in transportation (kgoe/vkm) and plant's

6

operation (kgoe/h) generate CO2eq emissions which are clearly more prominent in

7

transportation than in operation.

8

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

9

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

10

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

11

ed in 3.1.2). In both impact categories, however, incorporated impacts are very-small-

12

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

13

placement necessary for 60 years.

14

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

15

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

16

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

17

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

18

(Thormark, 2006).

19

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

20

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

21

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

22

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

23

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

24

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

25

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

26

unit in these waste processing industrial facilities. However, and in order to establish a 13

1

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

2

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

3

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

4

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

5

Insert Table 9

6

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

7

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

8

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

9

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

10

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

11

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

12

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

13

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

14

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

15

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

16

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

17

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

18

considered low priority.

19 20

5.

21

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

22

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

23

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

24

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

25

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

26

Other simplifications were considered, such as construction/retrofit sites’ distance to the 14

CONCLUSIONS

1

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

2

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

3

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

4

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

5

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

6

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

7

sions can be drawn:

8

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

9

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

10

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

11

as 8 times for primary energy consumption;

12

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

13

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

14

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

15

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

16

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

17

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

18

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

19

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

20

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

21

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

22

and the main producers are prototyping;

23

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

24

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

25

and associated transport needs);

26

- This kind of CDW recycling facility has greater primary energy and CO2eq emission 15

1

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

2

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

3

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

4

of primary energy consumption.

5 6

6.

ACKNOWLEDGEMENTS

7

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

8

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

9 10

7.

11

Blengini, G.A.; Garbarino, E, 2010. Resources and waste management in Turin (Italy):

12

the role of recycled aggregates in the sustainable supply mix. Journal of Cleaner Pro-

13

duction, 18 (10-11), 1021-1030

14

Blengini, G.A., 2009. Life cycle of buildings, demolition and recycling potential: a case

15

study in Turin, Italy. Building and Environment, 44 (2), 319-330

16

Börjesson, P.; Gustavsson, L., 2000. Greenhouse has balance in building construction:

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wood versus concrete from life-cycle and forest land-use perspectives. Energy Policy,

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28 (9), 575-588

19

Bribián, I.Z.; Capilla, A.V.; Usón, A.A., 2011. Life cycle assessment of building materi-

20

als: comparative analysis of energy and environmental impacts and evaluation of the

21

eco-efficiency improvement potential. Building and Environment, 46 (5), 1133-1140

22

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21

1

FIGURE CAPTIONS

2

Figure 1 - General layout sequence for the CDW recycling plan

3

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

4

rough geometrical centres of Lisbon statistical regions’ municipalities

5

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

6

mary energy consumption (due to replaced industrial processes)

7

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

8

sions (due to replaced industrial processes)

9

22

Input

Visual inspection

Loads contaminated with potencially hazardous materials

Weighting Scales

Large volume material separation - Excavator Breaking acessories as hydraulic hammer and scissors conveyor Size separation Metals Paper Plastics Wood

Vibrating feeder Manual separation (>80mm) conveyor Magnetic separation Crushing plant

Magnet Crusher

Ferrous metals

Size separation Horizontal screens (dry) (>40mm; 4mm; 4mm

Heavy metals separation Spirals (wet)

Density separator Air jig

Ceramic aggregates

Fines separation Spirals (wet)

Density separator Air jig

gypsum

concrete + sand fines

concrete aggregates

wet sludges Ceramic fines

1 2 3

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

4

23

1 2 3 4

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

5

24

Accumulated primary energy consumption, kgoe

6.0E+08

trimary energy consumption CDW recycling facility Avoided primary energy consumption

5.0E+08

4.0E+08

3.0E+08

2.0E+08

1.0E+08

0.0E+00 0

5

10

15

20

25

30

35

40

45

50

55

60

Years

1 2 3

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

4 CO2eq. emissions - CDW recycling facility CO2eq. avoided emissions

Accumulated CO2eq. emissions, kg CO2 eq.

1.6E+09 1.4E+09 1.2E+09 1.0E+09 8.0E+08 6.0E+08 4.0E+08 2.0E+08 0.0E+00 0

5

10

15

20

25

30

35

40

45

50

55

60

Years

5 6 7

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

8

25

1

TABLE CAPTIONS

2

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

3

facility

4

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

5

cation

6

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

7

cation

8

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

9

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

10

industries (kWh/ton)

11

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

12

recycled materials input in several industries

13

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

14

sion results for the CDW recycling facility

15

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

16

emissions per activity

17

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

18

and CO2eq emissions

19

26

1 2

Table 1 - Main attributes of equipment considered for the 350 tonnes/h CDW recycling facility Equipment (each unit)

3 4 5

Capacity, Power, tonnes/h 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: - Further details on this data can be found in (Coelho and de Brito, 2013)Error! Reference source not found..

27

1 2

Table 2 - CDW recycling plant equipment: incorporated environmental impact quantification Equipment Scales Excavator Vibrating feeder Magnet (ferrous metals) Manual separation cabinet

3 4 5 6 7 8

Average weight, Equipment made of (mate- Primary energy conkg/unit rial) (c) sumption, kWh/unit

CO2eq emission, kgCO2eq/unit

8 825 20 315 4 466 4 458

62 315 143 448 31 537 31 479

15 709 36 161 7 950 7 935

35 830

11 770

(a)

Steel (section) Steel (section) Steel (section) Steel (section) Steel sheet, concrete and polyurethane foam

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: (a) Environmental impact factors determined per m2, based on figures from (ITEC, 2011). (b) One group module of 23 individual spirals. (c) Although the items of equipment are composed of many other materials, for simplicity’s sake it is considered that they are made only of the listed material (which in fact accounts for most of its mass in weight).

28

1 2

Table 3 - CDW recycling plant equipment: operational environmental impact quantification Equipment

3 4 5

Power, kW/unit

Scales 0.05 Excavator 90 Vibrating feeder 16.2 Magnet (ferrous metals) 6.5 Manual separation cabinet 0.28 Crusher 110 Horizontal screen 1 18.5 Air sifter 6.3 Eddy current generator (non-ferrous metals) 16.4 Horizontal screen 2 22.3 Air jig 127 Spirals 27 Conveyors Variable Notes: (a) All installed units.

29

Energy utilised

Primary energy conCO2eq emission, sumption, kgoe/year (a) kgCO2eq/year (a)

Electricity Diesel Electricity Electricity Electricity Electricity Electricity Electricity Electricity Electricity Electricity Electricity Electricity

35 18 576 11 275 4 524 136 76 560 12 876 9 135 7 990 15 544 476 189 114 631 49 010

42 56 322 13 530 5 429 164 91 872 15 451 10 962 9 588 18 653 571 427 137 557 58 812

1

Table 4 - Transportation needs for routing the CDW recycling facility output materials Materials Ferrous metals Non-ferrous metals (mainly aluminium)

Distance from Transported Amadora geomet- weight, rical centre, km tonnes/year

Total disTransported Freight tance trans3 volume, m number ported, km

32

14 051

10 036

519

16 623

32

37

26

1

44

32

301

215

11

357

22.7

36 626

26 161

1 354

30 738

7.8

36 626

26 161

1 354

10 562

41

36 626

26 161

1 354

55 518

39

36 626

26 161

1 354

52 810

22.7

48 760

34 829

1 803

40 922

7.8

48 760

34 829

1 803

14 061

41

48 760

34 829

1 803

73 912

39

48 760

34 829

1 803

70 307

21 (a)

133 985

95 703

4 954

104 141

21 (a)

178 749

127 678

6 609

138 934

Portucel, Setúbal

63

3 502

2 501

129

8 156

Revolta

7

600

429

22

155

Revolta

7

9 546

6 819

353

2 471

Renascimento

15

9 546

6 819

353

Possible destination (companies)

Ecometais

Heavy metals

Concrete aggregate (coarse)

Concrete aggregate (fine)

Ceramic aggregates (coarse) Ceramic aggregates (fine) Paper and cardboard Plastics Wood

2 3 4 5

Betecna - Oeiras Betão Liz - Carnaxide Camilo & Lopez Moita Camilo & Lopez Montijo Betecna - Oeiras Betão Liz - Carnaxide Camilo & Lopez Moita Camilo & Lopez Montijo Generic use in roadwork

5 294 Notes: (a) Since it is impossible to know where most of the aggregates will be placed in the Lisbon Metropolitan region, the same average of 21 km is assumed, as described in 3.1.3.

30

1 2

Table 5 - End-use energy consumption profile for the main stages in several product industries (kWh/ton) Industrial stage Product industry

3 4 5 6 7 8

Extraction to the factory gate Transportation (d) Process Boat (transocean tanker)

Freight train Truck

Percentage of enduse energy avoided if incoming secFinal production ondary raw materials are used, %

Wood particleboard and 269.1 0.0 18.0 618.7 2913 23.7 fibreboard (a) 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: (a) Source data from Ecoinvent database (Werner et al., 2007). (b) Source data from Ecoinvent database (Hischier, 2007). (c) Source data from Ecoinvent database (Classen et al., 2009). (d) Source data from Ecoinvent database - Transportation (Spielmann et al., 2007) and Fuel (Dones et al., 2007).

31

1 2

Table 6 - Prevented environmental impacts due to virgin raw material replacement by recycled materials input in several industries Replaced CDW recycling facili- portion of the Virgin raw material ty output material industrial to be replaced process Ferrous metals Non-ferrous metals (mainly aluminium) Heavy metals

Iron ore From extrac- Bauxite ore tion to final Mercury stage input (a) Ores of Nickel Cadmium

Concrete aggregates (coarse) Concrete aggregates (fine) Ceramic aggregates (coarse) (c) Ceramic aggregates (fine) (c) Paper and cardboard Plastics Wood

3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

From extraction to the factory output gate (b)

From extraction to the factory input gate

Limestone crushed aggregates

Industrial processes: prevented energy and CO2 emissions Emissions Primary energy kWh/ton 2740

kgoe/ton 236

kgCO2eq./ton 805

47083

4048

9944

24169 45559 -

2078 3917 -

5236 13144 -

12.39

1.07

3.1

Source reference

(Geoff and Craig, 2011)

-

(Weil et al., 2006) River/sea sand

9.58

0.82

2.2

Cellulose (e) Oil derivatives

5452 22363

469 1923

862 3310

Wood particleboard and fibreboard (d)

972

84

168

(Geoff and Craig, 2011)

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

32

1 2

Table 7 - Initial, yearly and 60-year total primary energy consumption and CO2eq emission results for the CDW recycling facility Energy consumption/emissions Embodied primary energy, first year, kgoe Operation primary energy, kgoe/year Transport primary energy, kgoe/year

219 547 796 482 380 889

Incorporated CO2eq, first year, kgCO2eq Operation CO2eq, kgCO2eq/year

643 984 989 810

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

3 4

33

Total primary energy consumption, kgoe Total CO2eq emission, kgCO2eq Total primary energy prevented consumption, kgoe Total CO2eq prevented emission, kgCO2eq Total prevented primary energy/total consumption

71 430 578 135 357 575 562 622 431 1 465 270 986 7.9

Total prevented CO2eq emissions/total emitted

10.8

1 2

Table 8 - CDW recycling facility’s 60-year primary energy consumption and CO2eq emissions per activity Impact activity Incorporated Operation Transportation All activity

3 4

34

Primary energy consumption toe x 1000 0.80 47.8 22.9 71.4

% 1.12 66.9 32.0 100

CO2eq. emission Tonnes CO2eq x 1000 2.31 59.4 73.7 135.4

% 1.71 43.9 54.4 100

1 2 3

Table 9 - Comparison between waste treatment processes - primary energy consumption and CO2eq emissions Waste treatment system

4 5 6 7

Global unit impacts (a) Primary energy consumption kgoe/ton -584.7 -87.1 -115.0

CO2eq emission kgCO2eq/ton -1583 -27.0 -155.2

CDW recycling plant MSW treatment in Bologna (b) MSW treatment in Avellino (c) Notes: (a) Figures per tonne of processed material, including prevented impacts. (b) (Buttol et al., 2007) (c) (De Feo and Malvano, 2009)

35

% of mass sent for recycling 84 28 80