electronic supplementary material

LCA of Chemicals

Comparative LCA of multi-product processes with non-common products: a systematic approach applied to chlorine-electrolysis technologies

Johannes Jung • Niklas von der Assen • André Bardow

Received: 4 July 2011 / Accepted: 6 November 2012

© Springer-Verlag 2012

Responsible editor: Liselotte Schebek

Johannes Jung • Niklas von der Assen • André Bardow ()

Lehrstuhl für Technische Thermodynamik, RWTH Aachen University, Schinkelstr. 8, 52062 Aachen, Germany

e-mail:

() Corresponding author:

André Bardow

Phone:+49-241-80-95380

Fax:+49-241-80-92255

e-mail:

1Matrices used during application of the framework

Table S1 Technology matrix A and possible final demand matrices FI, FII, and FIII for chlorine production scenarios.Heat generation and concentration process for NaOH are equal for both electrolysis technologies and therefore not displayed

A / FI
Cl2 / FII
Cl2, NaOH
/ FIII
Cl2,NaOH,
H2
row / flow / unit / electricity generation / NaCl extraction / air fractionation / membrane- process / ODC-process / steam reformer / / / / / /
1 / electricity / kWh / 1 / 0 / 0 / -2.34 / -1.56 / 0 / 0 / 0 / 0 / 0 / 0 / 0
2 / NaCl / kg / 0 / 1 / 0 / -1.65 / -1.65 / 0 / 0 / 0 / 0 / 0 / 0 / 0
3 / O2, airfractionation / kg / 0 / 0 / 1 / 0 / -0.23 / 0 / 0 / 0 / 0 / 0 / 0 / 0
4 / N2,airfractionation / kg / 0 / 0 / 3.35 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
5 / Cl2, membrane / kg / 0 / 0 / 0 / 1 / 0 / 0 / 1 / 0 / 1 / 0 / 1 / 0
6 / NaOHmembrane / kg / 0 / 0 / 0 / 1.13 / 0 / 0 / 0 / 0 / 1.13 / 0 / 1.13 / 0
7 / H2,membrane / kg / 0 / 0 / 0 / 0.03 / 0 / 0 / 0 / 0 / 0 / 0 / 0.03 / 0
8 / Cl2,ODC / kg / 0 / 0 / 0 / 0 / 1 / 0 / 0 / 1 / 0 / 1 / 0 / 1
9 / NaOHODC / kg / 0 / 0 / 0 / 0 / 1.13 / 0 / 0 / 0 / 0 / 1.13 / 0 / 1.13
10 / H2,steamreformer / kg / 0 / 0 / 0 / 0 / 0 / 1 / 0 / 0 / 0 / 0 / 0 / 0.03

Main-Products: Cl2 and NaOH (Scenario II)

Table S2 Main-product technology matrix , final demand matrix FII and discrepancy matrix for main-products Cl2 and NaOH

/ FII
Cl2, NaOH /
row / flow / unit / electricity / NaCl extraction / air fractionation / membrane / ODC / steam reformer / / / /
1 / electricity / kWh / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
2 / NaCl / kg / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
3 / O2, airfractionation / kg / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
4 / N2,airfractionation / kg / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
5 / Cl2, membrane / kg / 0 / 0 / 0 / 1 / 0 / 0 / 1 / 0 / 0 / 0
6 / NaOHmembrane / kg / 0 / 0 / 0 / 1.13 / 0 / 0 / 1.13 / 0 / 0 / 0
7 / H2,membrane / kg / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
8 / Cl2,ODC / kg / 0 / 0 / 0 / 0 / 1 / 0 / 0 / 1 / 0 / 0
9 / NaOHODC / kg / 0 / 0 / 0 / 0 / 1.13 / 0 / 0 / 1.13 / 0 / 0
10 / H2,steamreformer / kg / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0

Table S3 Technology matrix A, final demand matrix FII and discrepancy matrix DIIfor main-products Cl2 and NaOH

A / FII
Cl2, NaOH / DII
row / flow / unit / electricity / NaCl extraction / air fractionation / membrane / ODC / steam reformer / / / /
1 / electricity / kWh / 1 / 0 / 0 / -2.34 / -1.56 / 0 / 0 / 0 / 0 / 0
2 / NaCl / kg / 0 / 1 / 0 / -1.65 / -1.65 / 0 / 0 / 0 / 0 / 0
3 / O2, airfractionation / kg / 0 / 0 / 1 / 0 / -0.23 / 0 / 0 / 0 / 0 / -0.21
4 / N2,airfractionation / kg / 0 / 0 / 3.35 / 0 / 0 / 0 / 0 / 0 / 0 / 0.06
5 / Cl2, membrane / kg / 0 / 0 / 0 / 1 / 0 / 0 / 1 / 0 / 0 / 0
6 / NaOHmembrane / kg / 0 / 0 / 0 / 1.13 / 0 / 0 / 1.13 / 0 / 0 / 0
7 / H2,membrane / kg / 0 / 0 / 0 / 0.03 / 0 / 0 / 0 / 0 / 0.03 / 0
8 / Cl2,ODC / kg / 0 / 0 / 0 / 0 / 1 / 0 / 0 / 1 / 0 / 0
9 / NaOHODC / kg / 0 / 0 / 0 / 0 / 1.13 / 0 / 0 / 1.13 / 0 / -0.02
10 / H2,steamreformer / kg / 0 / 0 / 0 / 0 / 0 / 1 / 0 / 0 / 0 / -0.02

Table S4 Modified technology matrix , final demand matrix and discrepancy matrix for main-products Cl2 and NaOH

/
Cl2, NaOH /
row / flow / unit / electricity / NaCl supply / oxygen,
air frac / nitrogen,
air frac / membrane / ODC / steam reformer / f2,m / f2,O / d2,m / d2,O
1 / electricity / kWh / 1 / 0 / 0 / 0 / -2.34 / -1.56 / 0 / 0 / 0 / 0 / 0
2 / NaCl / kg / 0 / 1 / 0 / 0 / -1.65 / -1.65 / 0 / 0 / 0 / 0 / 0
3 / O2, airfractionation / kg / 0 / 0 / 1 / 0 / 0 / -0.23 / 0 / 0 / 0 / 0 / 0
4 / N2,airfractionation / kg / 0 / 0 / 0 / 3.35 / 0 / 0 / 0 / 0 / 0 / 0 / 0
5 / Cl2, membrane / kg / 0 / 0 / 0 / 0 / 1 / 0 / 0 / 1 / 0 / 0 / 0
6 / NaOHmembrane / kg / 0 / 0 / 0 / 0 / 1.13 / 0 / 0 / 1.13 / 0 / 0 / 0
7 / H2 / kg / 0 / 0 / 0 / 0 / 0.03 / 0 / 1 / 0 / 0 / 0 / 0
8 / Cl2,ODC / kg / 0 / 0 / 0 / 0 / 0 / 1 / 0 / 0 / 1 / 0 / 0
9 / NaOHODC / kg / 0 / 0 / 0 / 0 / 0 / 1.13 / 0 / 0 / 1.13 / 0 / 0

Main-Products: Cl2, NaOH and H2 (Scenario III)

Table S5 Main-product technology matrix , final demand matrix FIII and discrepancy matrix for main-products Cl2, NaOH and H2

/ FIII
Cl2, NaOH,
H2 /
row / flow / unit / electricity / NaCl extraction / air fractionation / membrane / ODC / steam reformer / / / /
1 / electricity / kWh / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
2 / NaCl / kg / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
3 / O2, airfractionation / kg / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
4 / N2,airfractionation / kg / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
5 / Cl2, membrane / kg / 0 / 0 / 0 / 1 / 0 / 0 / 1 / 0 / 0 / 0
6 / NaOHmembrane / kg / 0 / 0 / 0 / 1.13 / 0 / 0 / 1.13 / 0 / 0 / 0
7 / H2,membrane / kg / 0 / 0 / 0 / 0.03 / 0 / 0 / 0.03 / 0 / 0 / 0
8 / Cl2,ODC / kg / 0 / 0 / 0 / 0 / 1 / 0 / 0 / 1 / 0 / 0
9 / NaOHODC / kg / 0 / 0 / 0 / 0 / 1.13 / 0 / 0 / 1.13 / 0 / 0
10 / H2,steamreformer / kg / 0 / 0 / 0 / 0 / 0 / 1 / 0 / 0.03 / 0 / 0

Table S6 Technology matrix A, final demand matrix FIII and discrepancy matrix DIIIfor main-products Cl2, NaOH and H2

A / FIII
Cl2, NaOH, H2 / DIII
row / flow / unit / electricity / NaCl extraction / air fractionation / membrane / ODC / steam reformer / / / /
1 / electricity / kWh / 1 / 0 / 0 / -2.34 / -1.56 / 0 / 0 / 0 / 0 / 0
2 / NaCl / kg / 0 / 1 / 0 / -1.65 / -1.65 / 0 / 0 / 0 / 0 / 0
3 / O2, airfractionation / kg / 0 / 0 / 1 / 0 / -0.23 / 0 / 0 / 0 / 0 / -0.21
4 / N2,airfractionation / kg / 0 / 0 / 3.35 / 0 / 0 / 0 / 0 / 0 / 0 / 0.06
5 / Cl2, membrane / kg / 0 / 0 / 0 / 1 / 0 / 0 / 1 / 0 / 0 / 0
6 / NaOHmembrane / kg / 0 / 0 / 0 / 1.13 / 0 / 0 / 1.13 / 0 / 0 / 0
7 / H2,membrane / kg / 0 / 0 / 0 / 0.03 / 0 / 0 / 0.03 / 0 / 0 / 0
8 / Cl2,ODC / kg / 0 / 0 / 0 / 0 / 1 / 0 / 0 / 1 / 0 / 0
9 / NaOHODC / kg / 0 / 0 / 0 / 0 / 1.13 / 0 / 0 / 1.13 / 0 / -0.02
10 / H2,steamreformer / kg / 0 / 0 / 0 / 0 / 0 / 1 / 0 / 0.03 / 0 / -0.02

Table S7 Modified technology matrix , final demand matrix FIII and discrepancy matrix for main-products Cl2, NaOH and H2

/ FIII
Cl2,
NaOH, H2 /
row / flow / unit / electricity / NaCl supply / oxygen,
air frac / nitrogen,
air frac / membrane / ODC / steam reformer / / / /
1 / electricity / kWh / 1 / 0 / 0 / 0 / -2.34 / -1.56 / 0 / 0 / 0 / 0 / 0
2 / NaCl / kg / 0 / 1 / 0 / 0 / -1.65 / -1.65 / 0 / 0 / 0 / 0 / 0
3 / O2, airfractionation / kg / 0 / 0 / 1 / 0 / 0 / -0.23 / 0 / 0 / 0 / 0 / 0
4 / N2,airfractionation / kg / 0 / 0 / 0 / 3.35 / 0 / 0 / 0 / 0 / 0 / 0 / 0
5 / Cl2, membrane / kg / 0 / 0 / 0 / 0 / 1 / 0 / 0 / 1 / 0 / 0 / 0
6 / NaOHmembrane / kg / 0 / 0 / 0 / 0 / 1.13 / 0 / 0 / 1.13 / 0 / 0 / 0
7 / H2,membrane / kg / 0 / 0 / 0 / 0 / 0.03 / 0 / 0 / 0.03 / 0 / 0 / 0
8 / Cl2,ODC / kg / 0 / 0 / 0 / 0 / 0 / 1 / 0 / 0 / 1 / 0 / 0
9 / NaOHODC / kg / 0 / 0 / 0 / 0 / 0 / 1.13 / 0 / 0 / 1.13 / 0 / 0
10 / H2,steamreformer / kg / 0 / 0 / 0 / 0 / 0 / 0 / 1 / 0 / 0.03 / 0 / 0

Main Product: Cl2

Table S8 Main-product technology matrix , final demand matrix FI and discrepancy matrix for main-product Cl2

/ FI
Cl2 /
row / flow / unit / electricity / NaCl extraction / air fractionation / membrane / ODC / steam reformer / / / /
1 / electricity / kWh / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
2 / NaCl / kg / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
3 / O2, airfractionation / kg / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
4 / N2,airfractionation / kg / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
5 / Cl2, membrane / kg / 0 / 0 / 0 / 1 / 0 / 0 / 1 / 0 / 0 / 0
6 / NaOHmembrane / kg / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
7 / H2,membrane / kg / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
8 / Cl2,ODC / kg / 0 / 0 / 0 / 0 / 1 / 0 / 0 / 1 / 0 / 0
9 / NaOHODC / kg / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
10 / H2,steamreformer / kg / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0

Table S9 Technology matrix A, final demand matrix FI and discrepancy matrix DIfor main-product Cl2

A / FI
Cl2 / DI
row / flow / unit / electricity / NaCl extraction / air fractionation / membrane / ODC / steam reformer / / / /
1 / electricity / kWh / 1 / 0 / 0 / -2.34 / -1.56 / 0 / 0 / 0 / 0 / 0
2 / NaCl / kg / 0 / 1 / 0 / -1.65 / -1.65 / 0 / 0 / 0 / 0 / 0
3 / O2, airfractionation / kg / 0 / 0 / 1 / 0 / -0.23 / 0 / 0 / 0 / 0 / -0.09
4 / N2,airfractionation / kg / 0 / 0 / 3.35 / 0 / 0 / 0 / 0 / 0 / 0 / 0.03
5 / Cl2, membrane / kg / 0 / 0 / 0 / 1 / 0 / 0 / 1 / 0 / -0.56 / 0
6 / NaOHmembrane / kg / 0 / 0 / 0 / 1.13 / 0 / 0 / 0 / 0 / 0.50 / 0
7 / H2,membrane / kg / 0 / 0 / 0 / 0.03 / 0 / 0 / 0 / 0 / 00.1 / 0
8 / Cl2,ODC / kg / 0 / 0 / 0 / 0 / 1 / 0 / 0 / 1 / 0 / -0.57
9 / NaOHODC / kg / 0 / 0 / 0 / 0 / 1.13 / 0 / 0 / 0 / 0 / 0.49
10 / H2,steamreformer / kg / 0 / 0 / 0 / 0 / 0 / 1 / 0 / 0 / 0 / 0

Table S10 Manipulated technology matrix , final demand matrix FI and discrepancy matrix for main- product Cl2

/ F1
Cl2 /
row / flow / unit / electricity / NaCl supply / oxygen, air frac / nitrogen, air frac / chlorine, membrane / NaOH, membrane / hydrogen, membrane / chlorine, ODC / NaOH, ODC / steam reformer / / / /
1 / electricity / kWh / 1 / 0 / 0 / 0 / -λ1∙2.34 / -λ2∙2.34 / -λ3∙2.34 / -λ4∙1.56 / -λ5∙1.56 / 0 / 0 / 0 / 0 / 0
2 / NaCl / kg / 0 / 1 / 0 / 0 / -λ1∙1.65 / -λ2∙1.65 / -λ3∙1.65 / -λ4∙1.65 / -λ5∙1.65 / 0 / 0 / 0 / 0 / 0
3 / O2, airfractionation / kg / 0 / 0 / 1 / 0 / 0 / 0 / 0 / -λ4∙0.23 / -λ5∙0.23 / 0 / 0 / 0 / 0 / 0
4 / N2,airfractionation / kg / 0 / 0 / 0 / 3.35 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
5 / Cl2, membrane / kg / 0 / 0 / 0 / 0 / 1 / 0 / 0 / 0 / 0 / 0 / 1 / 0 / 0 / 0
6 / NaOHmembrane / kg / 0 / 0 / 0 / 0 / 0 / 1.13 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
7 / H2,membrane / kg / 0 / 0 / 0 / 0 / 0 / 0 / 0.03 / 0 / 0 / 0 / 0 / 0 / 0 / 0
8 / Cl2,ODC / kg / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 1 / 0 / 0 / 0 / 1 / 0 / 0
9 / NaOHODC / kg / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 1.13 / 0 / 0 / 0 / 0 / 0
10 / H2,steamreformer / kg / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 1 / 0 / 0 / 0 / 0

2 Comparative impact assessment formula

For comparative studies containing a total number of r alternative product systems it is useful to define a relative impact difference matrix:

. (17)

Columns of represent the relative environmental impact differences between the k-th alternative and a reference system. The values are computed by dividing the impact differences by the values of a reference alternative.

3Alternative allocation methods

Physical relationships for deriving allocation factors cannot be applied (Azapagic and Clift 1999a) because electrolysis is by nature a joint-production process. Possible allocation factors are thus only physical and economic characteristics. Table 11 summarizes the product characteristics evaluated in this work. Mass and molar quantities of the products are determined by the stoichiometric reaction Eqs. (14) and (15).

Table S11 Product characteristics used for computingallocation factors

method / unit / Cl2 / NaOH / H2
mass / kg / 1.00 / 1.13 / 0.03
molar quantity / mol / 1 / 2 / 1
exergy / kJ/mol / 126.3 / 72.6 / 238.2
market value / €/t / 200 / 450 / 1750

The quality of a chemical product is not characterized by mass or molar quantities. Instead, the exergy of the products is calculated using the method given by Szargut et al. (1988) and Sankaranarayanan et al. (2010). Market values of chlorine and caustic soda can be found in Icis (2011). Hydrogen prices for different steam reformer capacities are estimated by Doty (2004) and used in this study. The obtained allocation factors are shown in Figure 3. The allocation factors using mass fraction and market value fraction are similar for both technologies because the fractions of hydrogen are low. In contrast, the allocation factors based on molar and exergy fraction assign significantly higher impacts to hydrogen for the membrane process. Consequently, it is expected that the results for membrane- and ODC-systems will differ significantly depending on the allocation method used for scenario FI.


Fig. S1 Allocation factors for alternative electrolysis technologies

4 Expanded results for alternative allocation methods

Table S12 Results of membrane-/ODC-technology comparison using main-product scenarios FI, FII, and FIII

FI
main-products:
Cl2 / FII
main-products:
Cl2, NaOH / FIII
main-products:
Cl2, NaOH, H2
allocation:
mass / allocation:
molar / allocation:
exergy / allocation:
market value / burden:
steam ref. / expansion:
steam ref.
CED / -24% / +/- 0% / +41% / -21% / -9% / -8%
GWP100 / -22% / +3% / +45% / -19% / -3% / -3%
AP / -24% / +1% / +41% / -21% / -20% / -19%
POCP / -21% / +4% / +46% / -18% / -16% / -15%
EP / -17% / +9% / +54% / -14% / -14% / -14%
HTP / -10% / +19% / +68% / -6% / -11% / -11%

The results of the scenario FIusing only chlorine as main-product depend on the chosen allocation factor: Applying molar or exergy fraction of the outputs as allocation factor leads to lower environmental impacts for the membraneprocess system in all assessed categories. Basing allocation on mass or market-value fractions of the outputs yields similar results as the scenarios FII and FIII using multiple main-products. The underlying reason for the similarity is the low mass and market value fractions of the non-common by-product hydrogen.

Additional References

Doty FD (2004) A realistic look at hydrogen price projections. Doty Scientific, Inc. Columbia, SC. Accessed 30 March 2011

Icis (2011) Chemical price reports. Available online: (Accessed 28 March 2011)

Sankaranarayanan K, van der Kooi HJ, de Swaan Arons J (2010) Efficiency and sustainability in the energy and chemical industries - scientific principles and case studies. CRC Press, Boca Raton

Szargut J, Morris DR, Steward FR (1988) Exergy analysis of thermal, chemical, and metallurgical processes. Springer, Berlin