LIFE CYCLE INVENTORY OF MUNICIPAL SOLID WASTE INCINERATION (MSWI) IN SPAIN AND PORTUGAL Margallo M. 1, Aldaco R. 1, Bala A. 2, Fullana P. 2, Irabien A. 1 Dpto. Ingeniería Química y Química Inorgánica. Universidad de Cantabria : ETSIIyT. Avda. de los Castros s/n 39005 Santander. SPAIN : aldacor@unican.es 2Escola Superior de Comerç Internacional (ESCI-ÚPF), : Pg. Pujades, 1.08003 Barcelona, SPAIN 1
1. Goal and scope
FUNCTIONAL UNIT (FU)
The aim of the work is to develop the LCI of incineration process in Spain and Portugal and to model it. The model will represent the average technology applied in these countries, as well as its average consumption, emissions, etc. Figure 1 shows the location of the MSWI plants in Spain and Portugal.
In MSW studies the FU should consider the period of time to which the environmental impacts and waste generation should be related, the amount of waste generated and its composition [1]. So the FU was 1 ton of MSW fractions (PET, HDPE, LDPE, plastic mix, paper and cardboard, beverage carton, glass, steel, Al and organic matter).
SYSTEM DESCRIPTION OUTPUTS
All material and energy inputs and outputs of the different incineration process stages were included. Out of system boundaries were the construction of major capital equipment, and the maintenance and operation of support equipment.
Grate furnace Fluidised bed
Figure 1. Incineration plants in Spain and Portugal.
INPUTS
Water
MAIN PRODUCT
ENERGY
Inert material
•Electric energy
SUBSYSTEM 3: Ash solidification
•Electric Energy MAIN INPUT •MSW
SOLID RESIDUES •Ash •Slag
SUBSYSTEM 1: Thermal and flue gases
ANCILLARY MATERIALS •Air •Water •Natural gas/diesel •Urea/NH3 •CaO/Ca(OH)2 •Activated C
SUBSYSTEM 2: Magnetic separation
EMISSIONS TO AIR •Organic compounds •Nitrogen compounds •Heavy metals •SOx •HCl, HF •CO2, CO, CH4 •Dust
treatment with energy recovery
SUBSYSTEM 4: Landfill Inert material
SUBSYSTEM 5: Steel production
Scrap Energy
Figure 2. System description.
2. Life Cycle Inventory LCI consist of annual material and energy inputs and outputs for the operation of Spanish and Portuguese incineration plants in 2009. Tables 1, 2 and 3 give the main inputs and outputs data [2], [3], [4].
Table 1. LCI of thermal and flue gases treatment.
3%
Organic matter
10% Rest of materials: Steel, Al, HDPE, beverage carton Paper and Cardboard non packaging Paper and cardboard packaging
Combustible/ ancillary materials (kg t-1MSW) INPUTS
• the Spanish Association of MSW valorisation plants (AEVERSU) • the Spanish packaging waste manager (Ecoembes) • Spanish and Portuguese incineration plants • European Pollutant Release and Transfer Register (E-PRTR)
• • • BIBLIOGRAPHIC •
3%
THERMAL AND FLUE GASES TREATMENT Natural gas
6.88E-01 Water
334
CaO
8.29
Gasoil
1.99E-01 Urea
3.34
Ca(OH)2
4.04
Air
3550
Ammonia
2.07 Activated Carbon
11%
46%
4.77E-01
LDPE packaging
Municipal Solid Waste (t year-1) Waste Waste (t
261,224
1.71E-01 Products (MJ t-1 MSW) Energy production
Ecoinvent database PE database Scientific Papers Reports
12%
t-1MSW)
Slag
Ashes
3,005 Self consumption
5.05E-02
Scrap
DATA
LIFE CYCLE INVENTORY
CO2
480 PCDD/F
Plastic mix non packaging Plastic mix packaging
1.95E-02
15%
325 Energy sales
Figure 2. Waste composition (Source: own elaboration based on Ecoembes data) .
2,931
Emissions to air (kg t-1MSW) OUTPUTS
SITE SPECIFIC DATA
THERMAL AND FLUE GASES TREATMENT
2.30E-10 As
3.96E-05
CO
1.21E-01 SOX
6.09E-02
Cd
1.16E-05
CH4
5.00E-04 NOX
9.15E-01
Cr
7.06E-05
NMVOC
1.20E-02 N2O
2.51E-02
Cu
4.53E-05
TOC
1.41E-02 NH3
1.68E-02
Pb
1.02E-04
PAHs
1.58E-04 TSP
1.11E-02
Mn
7.54E-05
HCl
2.56E-02 PM10
8.69E-03
Hg
7.35E-06
HF
1.23E-03 Zn
6.32E-04 Ni
TREATMENT OF ASHES AND SLAG Table 2. LCI of magnetic separation of slag.
Table 3. LCI of ash solidification.
MAGNETIC SEPARATION Power grid
INPUTS OUTPUTS
3.34E-05
ASH SOLIDIFICATION
3.11 MJ t-1 MSW
Slag
1.93E-01 t t-1 MSW
Inert material
1.72E-01 t t-1 MSW
Scrap
2.06E-02 t t-1 MSW
INPUTS
OUTPUTS
Ashes
4.33E-02 t t-1 MSW
Cement
1.73E-02 t t-1 MSW
Water
2.60E-02 t t-1 MSW
Ashes
58.66E-02 t t-1 MSW
3. Allocations Incineration is a multi input-output allocation process where several inputs and outputs coexist. ISO 14044 proposes the following hierarchy for dealing with allocation problems [5]:
1
If possible allocation should be avoided expanding the system boundaries or dividing the process into sub-processes. If this is not possible allocation rules should be applied
2
Allocation based on physical causation which reflects the underlying relation among different flows
3
When a physical causation relationship cannot be established allocation based on other criterion such as economic value, mass or energy should be applied
MASS ALLOCATION
3
Combustible, reagents and auxiliary materials consumption: there isn’t relation between these consumptions and waste composition so non causality criterions such as mass allocation must be applied.
2 Multi -input/output process O1 Emissions
NOx, N2O, and NH3; dust and PCCDF emissions: don´t depend on waste composition, but technology applied and incinerator operation. Mass allocation seems the best option, because it is a good descriptor of causing physical property of waste stream
Input waste fraction I1+ I2+ I3..In
Slag: among all waste fraction incinerated, only the inert materials (Steel, Aluminum, Glass, construction and demolition waste) unburnable waste, are completely transferred to the slag. Non inert materials are allocated by mass
O2 …
Solid residues
Energy
On
3
• Most relevant technologies applied in the MSW incineration in Spain and Portugal were determined. LCI data were collected E-PRTR, AEVERSU, Ecoembes and websites of different incineration plants. • Incineration is a multi-input/output allocation process. To solve this problem several allocation where applied. When a relationship could be established, physical allocation were applied and when this was not possible a mass or energy allocation was used. In these case, the main allocation applied mass and energy allocation and those based on the waste composition.
CO, CH4, CO2, NMVOC, PAH and TOC; SOX; HCl, HF and heavy metals and metalloids emissions were allocated according causality criterions, specifically to C, S, Cl, F, and heavy metals and metalloids content. CO2 emissions are related with C content of waste. Only fossil C contribute to CO2 emissions. Contribution of CH4, CO, NMVOC, TOC and PAHs to climate change is only partially dependent (for CO and CH4) or independent on fossil C content. They are allocated based on total C content
ENERGY ALLOCATION Energy production: Based on High Heating Value of waste fraction, theoretical energy produced is calculated. Real energy produced is allocated to each waste fraction
Ashes: as the inert materials aren´t incinerated, they are not transferred to the ashes. For this reason, the ashes are only allocated by mass to non inert materials
4. Conclusions
WASTE COMPOSITION ALLOCATION
5. References [1] Bjarnadóttir HJ, Friðriksson GB, Johnsen T, Sletsen H (2002) Guidelines for the use of LCA in the waste management sector. Nordtest Project nr. 1537-01, Espoo, Finland. [2] AEVERSU, Asociación empresarial de Valorización RSU. http://www.aeversu.com/. Accessed 15.10.2010. [3] Ecoembes, Ecoembalajes España S.A. http://www.ecoembes.com. Accessed 1.10.2010. [4] E-PRTR, European Pollutant and Release Transference Register. http://www.prtr-es.es/. Accessed 22.10.2010. [5] ISO, 2006. ISO 14044: Environmental management - Life cycle assessment -Requirements and guidelines.
6. Acknowledgement The authors gratefully acknowledge the financial support of FENIX-Giving packaging a New Life project.