Appendix 1

Additional information to the Proposed Methodology“Introduction of High Efficiency Electrolyzer in Caustic Soda Production Plant”

1. Calculation of electricity consumption of the reference electrolyzer
The electricity consumption of the reference electrolyzer is calculated by the electricity consumption of theproject electrolyzer (which is monitored) and ratio of specific electricity consumption (SEC) values between
reference and project electrolyzer, as follows:‫ܥܧ‬ோா,௜,௣ = ‫ܥܧ‬௉௃,௜,௣ ×whereܵ‫ܥܧ‬ோா,௜ܵ‫ܥܧ‬௉௃,௜

ECRE,i,p:

ECPJ,i,p:

SECRE,i:Electricity consumption of the reference electrolyzer iduring the period p [MWh/p]
Electricity consumption of the project electrolyzer i during
the period p [MWh/p]
SEC value of the reference electrolyzer i [kWh/t-NaOH]SECPJ,i:SEC value of the project electrolyzer i [kWh/t-NaOH]

SEC value of the project electrolyzer (SECPJ,i) is set to be the value of the performance guarantee provided
by manufacturer of the project electolyzer. SEC value of the reference electrolyzer (SECRE,i) is the default
value set in the next section.

2. SEC values of the reference electrolyzer
2.1. SEC values of electrolyzers
Japan Soda Industry Association made SEC value of electrolyzers in Japan available on their web site1. The
average SEC value is 2,364 kWh(DC)/t-NaOH in 2016, which is described with yellow line in Figure.1
below.

It is noted that there are 30 plants in Japan and all plants introduced the electrolyzer of Ion-exchange membrane (IEM) technology, and the SEC value is calculated based on the provided result fromeach plant.

On the other hand, according to a document “Best Available Techniques (BAT) Reference Document for theProduction of Chlor-alkali” (European Commission, 2014), the average of bipolar ion-exchange membraneelectrolyzers is reported as 2,574 kWh(AC)/t-Cl2. which is almost equal to 2,281 kWh(AC)/t-NaOH. Hencethe value is calculated to be within the range of 2,191 kWh(DC)/t-NaOH to 2,236 kWh(DC)/t-NaOH
assuming the general AC/DC efficiency of 96% to 98%, which is described with blue line in in Figure.1

1“Trends in electricity consumption, purchased / private electrify, and the power consumption rate” Japan Soda Industry Association,
https://www.jsia.gr.jp/en/data/statistics_08.pdf

1bellow.

The performance guaranteed values of SECs of possible model of bipolar ion­exchange membraneelectrolyzers available in Thailand were collected and averaged within the range of current density (CD) 2.9
kA/m2 to 5.4 kA/m2, taking the same CD ranges as those documented in the abovementioned document by
European Commission. The values are plotted with the gray dot in Figure.1 below. The averaged SEC value
is calculated as 1,999 kWh(DC)/t­NaOH, which is shown in the orange line in the Figure.1 below.

As a result, it is considered that the electrolyzer of the possible model available in Thailand has comparable
efficiency advantage as it has the lower SEC value than that of electrolyzers reported in the document
published in EU. Hence it is determined to be the reference electrolyzer.

Figure 1: SEC values of electrolyzers

2.2. Determination of SEC values of the reference electrolyzer in Thailand
In order to make it comparable, the SEC values of reference electrolyzer and project electrolyzer are bothbased on performance guarantee.

Considering the fact that SEC values are positively correlated with CD, the SEC values of referenceelectrolyzer are set into five range of CDs. Accordingly, the default values of SEC of the referenceelectrolyzer are as shown in Table 1 below.

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Table 1: Default value of SEC of the reference electrolyzer
CD [kA/m ] corresponding to SEC performance
SEC value of the reference electrolyzer [kWh/tguarantee of the project electrolyzer
NaOH]
4.0 ≦ CD ＜ 4.52,013
4.5 ≦ CD ＜ 5.02,038
5.0 ≦ CD ＜ 5.52,061
5.5 ≦ CD ＜ 6.02,086
6.0 ≦ CD ＜ 6.52,1102

3. Aged deterioration of SEC value in electrolyzers
It is known that SEC value worsens with operation time because of deterioration of ion-exchange membranes
and electrodes. It is considered that deterioration rate and its effect on SEC values are same on both reference
and project electrolyzer from the result of interviews from the manufacturers. Accordingly, deterioration rate
is not taken into account in the methodology as the reference emissions are calculated based on the ratio ofSEC values between reference and project electrolyzer.

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