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Joint Crediting Mechanism Approved Methodology TH_AM015“Introduction of High Efficiency Electrolyzer in Caustic Soda Production Plant”

A. Title of the methodology
Introduction of High Efficiency Electrolyzer in Caustic Soda Production Plant, Version 01.0

B. Terms and definitions
Terms

Definitions

Electrolyzer

An equipment used for the electrolysis of sodium chloridesolution, composed of an anode chamber, anode, cathodechamber, cathode, and an ion exchange membrane.

Ion-exchange membrane

Method for the electrolysis of sodium chloride solution(IEM) technologyseparating the cathode and anode chambers, in which acation exchange membrane possesses special properties that
permit only transmission of cations (positive ions) not ofanions (negative ions).

Bipolar electrolyzer

Electrolyzer in which the elements are connected in series
and the power supply is connected only to the end part of theelectrolyzer.

C. Summary of the methodology
Items
GHG

emissionmeasures

Summary
reduction Installing ion-exchange membrane electrolyzer, which reduces
electricity resistance of the electrolyzer unit and achieves power
consumption reduction in the caustic soda process.

Thismethodology applies to the project that introduces highefficiency electrolyzer in caustic soda production plant.
Calculation
emissionsofreference Reference emissions are GHG emissions from using referenceelectrolyzer, calculated with power consumption of projectelectrolyzer, ratio of the performance guaranteed values of1

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specific power consumptions (SECs) of reference/projectelectrolyzers and CO2 emission factor for consumed electricity.
Calculationofproject Project emissions are GHG emissions from using projectemissionselectrolyzer, calculated with power consumption of projectelectrolyzer and CO2 emission factor for electricity consumed.

Monitoring parameters⚫

Power consumption of project electrolyzer

D. Eligibility criteria
This methodology is applicable to projects that satisfy all of the following criteria.
Criterion 1

Bipolar electrolyzer(s), which employs an ion-exchange membrane technology,
is installed in the manufacturing process of caustic soda.

Criterion 2

SEC value of project electrolyzer under the standard conditions, 32% NaOH
and 90 degrees Celsius is less than threshold SEC value set in the table below
under the standard conditions, 32% NaOH and 90 degrees Celsius;
CD (Current density) [kA/m2]

Threshold SEC value of theelectrolyzer [kWh (DC)/t-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 < 6.52,110

SEC value of project electrolyzer is derived from performance guaranteed value
provided by manufacturer.

E. Emission Sources and GHG types
Reference emissions
Emission sources

GHG types
CO2Power consumption of reference electrolyzer

Project emissions
Emission sources

GHG types
CO2

Power consumption of project electrolyzer

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F. Establishment and calculation of reference emissions
F.1. Establishment of reference emissions
Reference emissions are calculated by multiplying power consumption of project electrolyzer
and ratio of SEC values of reference/project electrolyzer, and CO2 emission factor for
consumed electricity. The SEC value of reference electrolyzer is conservatively set as a default
value in the following manner to ensure net emission reductions.
All electrolyzers in the caustic soda process in Japan employ ion-exchange membrane
technology, and the average of SEC values of the electrolyzers is 2,364 kWh (DC)/t-NaOH(Japan Soda Industry Association, 2016).
The range of averaged SEC values of the bipolar electrolyzers in EU is from 2,191 kWh (DC)/tNaOH to 2,236 kWh (DC)/t-NaOH based on the document “Best Available Techniques (BAT)
Reference Document for the Production of Chlor-alkali, 2014” by assuming general AC/DC
efficiency of 96% to 98% (European Commission, 2014).
The performance guaranteed values of SECs of possible model of bipolar electrolyzer available
in Thailand were collected and averaged within the same CD ranges as those in the abovementioned document by European Commission (2.9 kA/m2 to 5.4 kA/m2). Accordingly, theaveraged SEC value is calculated as 1,999 kWh (DC)/t-NaOH.
As a result, it is considered that the possible model of bipolar electrolyzer which is available inthe country has comparable efficiency advantage as it has the lower SEC value than that ofelectrolyzers reported in the document published in EU. Hence it is determined to be thereference electrolyzer.
In order to make it comparable, the SEC values of reference and project electrolyzers are both
based on performance guarantee.
Considering the fact that SEC values are positively correlated with CD, the reference SEC
values are set into five range of CDs. The SEC values of the reference electrolyzer aredetermined as 2,013, 2,038, 2,061, 2,086 and 2,110 kWh (DC)/t-NaOH corresponding to therange of CDs of 4.0, 4.5, 5.0, 5.5 and 6.0 kA/m2 respectively.

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F.2. Calculation of reference emissions

𝑹𝑬𝒑 = ∑ 𝑬𝑪𝑹𝑬,𝒊,𝒑 × 𝑬𝑭𝒆𝒍𝒆𝒄 = ∑ (𝑬𝑪𝑷𝑱,𝒊,𝒑 ×
𝒊𝒊𝑺𝑬𝑪𝑹𝑬,𝒊) × 𝑬𝑭𝒆𝒍𝒆𝒄𝑺𝑬𝑪𝑷𝑱,𝒊REp:

Reference emissions during the period p [tCO2/p]

ECRE,i,p:

ECPJ,i,p:

SECRE,i:SECPJ,i:Power consumption of the reference electrolyzer i during
the period p [MWh/p]
Power consumption of the project electrolyzer i during theperiod p [MWh/p]
SEC value of the reference electrolyzer i [kWh(DC)/tNaOH]
SEC value of the project electrolyzer i [kWh(DC)/t-NaOH]

EFelec:CO2 emission factor for consumed electricity [tCO2/MWh]i:

Identification number of project electrolyzer [-]G. Calculation of project emissions

𝑷𝑬𝒑 = ∑ 𝑬𝑪𝑷𝑱,𝒊,𝒑 × 𝑬𝑭𝒆𝒍𝒆𝒄𝒊𝑃𝐸𝑝:

Project emissions during the period p [tCO2/p]

𝐸𝐶𝑃𝐽,𝑖,𝑝:Power consumption of the project electrolyzer i during theperiod p [MWh/p]

𝐸𝐹𝑒𝑙𝑒𝑐:CO2 emission factor for consumed electricity [tCO2/MWh]i:

Identification number of project electrolyzer [-]H. Calculation of emissions reductions

𝑬𝑹𝒑 = 𝑹𝑬𝒑 − 𝑷𝑬𝒑
ERp
REp
PEp:::Emission reductions during the period p [tCO2/p]
Reference emissions during the period p [tCO2/p]
Project emissions during the period p [tCO2/p]4

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I. Data and parameters fixed ex ante
The source of each data and parameter fixed ex ante is listed as below.
Parameter
SECRE,iDescription of dataSource

SEC value of the reference electrolyzer i [kWhAdditional information(DC)/t-NaOH].

The default values areThe default value is set by the following table.

derived from theperformance guaranteed

CD [kA/m2]

SEC value of thevalue of possible model

corresponding toreferenceelectrolyzer available in

SEC performanceelectrolyzer [kWhguarantee of the(DC)/t-NaOH]

The SECRE,i should be
revised if necessary fromproject electrolyzer

SECPJ,iThailand.

4.0 ≤ CD < 4.5

2,013

survey result which is

4.5 ≤ CD < 5.0

2,038

conducted by the Joint

5.0 ≤ CD < 5.5

2,061

Committee or project

5.5 ≤ CD < 6.0

2,086

participants.

6.0 ≤ CD < 6.5

2,110

SEC value of the project electrolyzer iPerformance guaranteed[kWh(DC)/t-NaOH].

value provided bymanufacturer of the projectelectrolyzer.

𝐸𝐹𝑒𝑙𝑒𝑐CO2 emission factor for consumed electricity Case 1)[tCO2/MWh].

[Grid electricity]

When the project electrolyzer consumes only 1) The

mostrecentvalue

grid electricity, 2) captive electricity or 3) available at the time ofelectricity directly supplied from other sources validation is applied and(e.g. independent power producer (IPP), small fixed for the monitoring
power producer (SPP) and very small power period thereafter. The data isproducer (VSPP)) to the project site, the project sourced

from“Gridparticipant applies the CO2 emission factor Emission Factor (GEF) ofrespectively.

Thailand”,endorsedby

When the project electrolyzer may consume Thailand Greenhouse Gas
electricity supplied from more than 1 electric Management
source, the project participant applies the CO2 (TGO)
emission factor with the lowest value.

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instructed

Organization

unlessbyotherwise
theJoint

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Committee.
[CO2 emission factor]
Case 1) Grid electricity

Case 2)The most recent value available from the source [Captive electricity]
stated in this table at the time of validation

For Option a)Specification of the captiveCase 2) Captive electricity including

powergeneration

systemcogeneration systemprovided𝐸𝐹𝑒𝑙𝑒𝑐 is determined based on the following

manufacturer ( 𝜂𝑒𝑙𝑒𝑐 [%]).

options:

CO2 emission factor of thea) Calculated from its power generation

fossil fuel type used in theefficiency (𝜂𝑒𝑙𝑒𝑐 [%]) obtained from

captive power generation

manufacturer’s specification.

system (𝐸𝐹𝑓𝑢𝑒𝑙 [tCO2/GJ])

bytheThe power generation efficiency based on lowerFor Option b)
Generated and supplied
generation system from the manufacturer’s
electricity by the captive
specification is applied;
power generation system(𝐸𝐺𝑃𝐽,𝑝 [MWh/p]).
100
𝐸𝐹𝑔𝑒𝑛 = 3.6 ×× 𝐸𝐹𝑓𝑢𝑒𝑙
Fuel amount consumed by𝜂𝑒𝑙𝑒𝑐
the captive power generation
system ( 𝐹𝐶𝑃𝐽,𝑝 [mass orb) Calculated from measured datavolume/p]).
The power generation efficiency calculated from Net calorific value (𝑁𝐶𝑉𝑓𝑢𝑒𝑙heating value (LHV) of the captive powermonitored data of the amount of fuel input for [GJ/mass or volume]) andpower generation ( 𝐹𝐶𝑃𝐽,𝑝 ) and the amount of CO2 emission factor of theelectricity generated (𝐸𝐺𝑃𝐽,𝑝 ) during the period p fuel ( 𝐸𝐹𝑓𝑢𝑒𝑙 [tCO2/GJ]) inis applied. The measurement is conducted with order of preference:
the monitoring equipment to which calibration 1) values provided by thecertificate is issued by an entity accredited under fuel supplier;national/international standards;

2)

𝐸𝐹𝑒𝑙𝑒𝑐 = 𝐹𝐶𝑃𝐽,𝑝 × 𝑁𝐶𝑉𝑓𝑢𝑒𝑙 × 𝐸𝐹𝑓𝑢𝑒𝑙 ×1
𝐸𝐺𝑃𝐽,𝑝Where:measurement

bytheproject participants;
3)

regionalor

national

default

valuesdefault values;

𝑁𝐶𝑉𝑓𝑢𝑒𝑙 : Net calorific value of consumed
fuel [GJ/mass or volume]4)

IPCC

provided in tables 1.2 and 1.4
of Ch.1 Vol.2 of 2006 IPCC

Note:

Guidelines on National GHG

In case the captive electricity generation system

Inventories. Lower value is6

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meets all of the following conditions, the value

applied.

in the following table may be applied to 𝐸𝐹𝑒𝑙𝑒𝑐
depending on the consumed fuel type.

[Captive electricity with⚫

The system is non-renewable generation

diesel fuel]system

CDM approved small scale

Electricity generation capacity of the system

methodology: AMS-I.A.

⚫

is less than or equal to 15 MW[Captive electricity withfuel type

Diesel fuelNatural gas

𝐸𝐹𝑒𝑙𝑒𝑐

0.8 *10.46 *2natural gas]
2006 IPCC Guidelines on*1 The most recent value at the time of

National GHG Inventories

validation is applied.

for the source of EF of*2 The value is calculated with the equation in the natural gas.
option a) above. The lower value of default CDM Methodological tool
effective CO2 emission factor for natural gas "Determining the baseline(0.0543tCO2/GJ), and the most efficient value of efficiency of thermal ordefault efficiency for off-grid gas turbine systems electric energy generation(42%) are applied.

systems version 02.0" for thedefault efficiency for off-Case 3) Electricity directly supplied fromgrid power plants.

other sources including cogeneration systemwith the evidence;

Case 3)[Electricity directly supplied
from other sources including
cogeneration system]
For Option a)b) The value calculated in the same manner forThethe option a) of 2) captive electricity as

information relevant to theinstructed above;

value of emission factor (e.g.

c) The value calculated in the same manner fordata of power generation,

the option b) of 2) captive electricity as

type of power plant, type of

instructed above;fossil fuel, period of time).

𝐸𝐹𝑒𝑙𝑒𝑐 is determined based on the following
options:a) The value provided by the electricity supplier

When the project electrolyzer may consume
electricity supplied from more than 1 electricsource, the project participant applies the CO2
emission factor with the lowest value.

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evidence

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History of the document
Version01.0

Date
20 September 2021Contents revisedElectronic decision by the Joint Committee
Initial approval.

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