IEC TR 62933-4-200:2024

Electrical Energy Storage (EES) Systems - Part 4-200: Guidance on environmental issues - Greenhouse gas (GHG) emissions assessment by electrical energy storage (EES) systems

IEC TR 62933-4-200:2024 describes aspects on reduction of greenhouse gas (GHG) emissions associated with electrical energy storage systems (EES systems), and presents current practices, research activities and related researches in each country.
This document is intended to be used by those involved in design, development and use of EES systems, the grids and the renewable energy sources in the grids, where various applications, including but not limited to long term ones (peak shaving, load levelling, backup power, etc.) and short term ones (frequency regulation, renewable energy stabilization, etc.), are considered.

General Information

• Status: Published
• Publication Date: 17-Apr-2024
• ICS: 13.020.30 - Environmental impact assessment
• Technical Committee: TC 120 - Electrical Energy Storage (EES) systems
• Drafting Committee: WG 4 - TC 120/WG 4
• Current Stage: PPUB - Publication issued
• Start Date: 18-Apr-2024
• Completion Date: 03-May-2024

Overview

IEC TR 62933-4-200:2024 - "Electrical Energy Storage (EES) Systems - Part 4-200: Guidance on environmental issues - Greenhouse gas (GHG) emissions assessment by electrical energy storage (EES) systems" is a Technical Report from the IEC that provides guidance on evaluating and reducing greenhouse gas (GHG) emissions associated with electrical energy storage (EES) systems. It summarizes current practices, national case studies, research activities and example estimation methods for GHG reduction when integrating EES with grids and renewable energy sources.

Key topics

• Scope and definitions: clear terms such as EES, BESS (battery energy storage system), grid, and GHG reduction to ensure consistent assessment language.
• General guidance: conceptual approaches to how EES can reduce GHG emissions by enabling higher renewable penetration and displacing fossil generation.
• Country case studies: documented practices and analyses from Korea, Japan and Australia (including examples like frequency response EES and Hornsdale Power Reserve) illustrating operational strategies and lessons learned.
• Estimation methods: example calculation approaches and academic methodologies for quantifying GHG reductions (including use-case based and energy-chain/economic evaluations).
• Applications and use cases: long‑term services (peak shaving, load levelling, backup power) and short‑term services (frequency regulation, renewable energy stabilization).
• Supporting content: figures, operational scenarios, algorithms, and an informative annex template for recording related publications and practices.

Practical applications

• Assessing the net GHG impact of deploying EES within a power system or behind-the-meter application.
• Comparing operational strategies (e.g., frequency regulation vs energy shifting) for their emissions-reduction effectiveness.
• Informing design choices and operational algorithms for BESS to maximize carbon benefits when paired with variable renewable energy.
• Supporting project developers, grid planners and regulators with example calculation methods and national practice summaries.

Who should use this standard

• EES and BESS designers and manufacturers
• Grid operators, system planners and utilities
• Renewable energy project developers and VPP/aggregator operators
• Environmental analysts, lifecycle assessors and policy makers
• Researchers studying GHG impacts of energy storage technologies

Related information

• Part of the IEC 62933 series on Electrical Energy Storage (EES); this document is a Technical Report (informative) rather than a prescriptive standard, intended to guide assessment and harmonize practices for GHG emissions evaluation across projects and jurisdictions.

Keywords: IEC TR 62933-4-200:2024, electrical energy storage, EES, GHG emissions, greenhouse gas reduction, BESS, grid integration, frequency regulation, peak shaving, renewable energy stabilization.

Standards Content (Sample)

IEC TR 62933-4-200 ®
Edition 1.0 2024-04
TECHNICAL
REPORT
Electrical Energy Storage (EES) Systems –
Part 4-200: Guidance on environmental issues – Greenhouse gas (GHG)
emission assessment by electrical energy storage (EES) systems

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IEC TR 62933-4-200 ®
Edition 1.0 2024-04
TECHNICAL
REPORT
Electrical Energy Storage (EES) Systems –

Part 4-200: Guidance on environmental issues – Greenhouse gas (GHG)

emission assessment by electrical energy storage (EES) systems

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 13.020.30  ISBN 978-2-8322-8728-6

– 2 – IEC TR 62933-4-200:2024  IEC 2024
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 General . 7
5 Current practices of EES systems usage in relation to GHG emissions reduction . 10
5.1 General . 10
5.2 Korea case (KR) . 10
5.2.1 Case name . 10
5.2.2 Overview . 10
5.2.3 View points . 11
5.2.4 Economics . 12
5.2.5 FR EES systems GHG emissions reduction calculation formula . 12
5.2.6 GHG emissions reduction . 13
5.3 Cases in Japan (JP) . 17
5.3.1 Case name . 17
5.3.2 Overview of the case . 17
5.3.3 Utilization of conventional BESS . 17
5.3.4 Advanced use of BESS . 18
5.3.5 Application example on the grid side. 19
5.3.6 Application example on the demand side . 21
5.3.7 Examples of consideration of GHG reduction by EES systems . 22
5.3.8 Multiple use of BESS . 25
5.4 Cases in Australia (AU) . 25
5.4.1 Case name . 25
5.4.2 Overview of the case . 25
5.4.3 The NSW energy programs . 26
5.4.4 Hornsdale Power Reserve . 29
5.4.5 Examples of consideration of GHG reduction by EES . 29
6 Example methods for estimating GHG reduction . 29
6.1 General . 29
6.2 Estimation method of green house gas reduction for EES systems based on
a use case [17] . 30
6.3 Environmental and economic evaluation of the introduction of CO reduction
surcharge and storage battery considering the energy chain [18] . 30
Annex A (informative) Template for related publications and current practices . 31
A.1 General . 31
A.2 Related publication title (who, organization, YYYY) . 31
A.3 Current practices of EES systems usage in relation to GHG emissions
reduction . 31
Bibliography . 32

Figure 1 – Actions to take against frequency fluctuation (short duration) . 8
Figure 2 – Current FR EES sites in Korea . 11
Figure 3 – FR EES system commercial operation . 11
Figure 4 – Data of loads for every 5 min during the first week of April (one week) . 14

Figure 5 – Frequency scenario at intervals of 5 min (Case 1) . 14
Figure 6 – Frequency scenario at intervals of 5 min (Case 2) . 14
Figure 7 – FR EES system operation algorithm in the normal status . 15
Figure 8 – EES system charging/discharging scenario at intervals of 5 min (Case1) . 15
Figure 9 – EES system charging/discharging scenario at intervals of 5 min (Case2) . 16
Figure 10 – Application of behind the meter . 18
Figure 11 – Problems caused by large-scale penetration of renewable energy . 18
Figure 12 – Background of BESS utilization in the power system . 19
Figure 13 – BESS for reducing grid frequency changes at Nishisendai substation (S/S) . 20
Figure 14 – Large BESS demonstration at Minamihayakita substation (S/S) . 20
Figure 15 – Energy shift demonstration by large BESS at Buzen battery substation
(S/S) . 21
Figure 16 – Role of aggregator for demand response (DR) . 21
Figure 17 – Virtual power plant (VPP) demonstration example . 22
Figure 18 – High added-value of a BESS . 25

Table 1 – Example of the power generation sources for each fuel source . 13
Table 2 – Hornsdale Power Reserve . 29

– 4 – IEC TR 62933-4-200:2024  IEC 2024
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL ENERGY STORAGE (EES) SYSTEMS –

Part 4-200: Guidance on environmental issues –
Greenhouse gas (GHG) emissions assessment
by electrical energy storage (EES) systems

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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shall not be held responsible for identifying any or all such patent rights.
IEC TR 62933-4-200 has been prepared by IEC technical committee 120: Electrical Energy
Storage (EES) systems. It is a Technical Report.
The text of this Technical Report is based on the following documents:
Draft Report on voting
120/351/DTR 120/364/RVDTR
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Report is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts in the IEC 62933 series, published under the general title Electrical energy
storage (EES) systems, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

– 6 – IEC TR 62933-4-200:2024  IEC 2024
ELECTRICAL ENERGY STORAGE (EES) SYSTEMS –

Part 4-200: Guidance on environmental issues –
Greenhouse gas (GHG) emissions assessment
by electrical energy storage (EES) systems

1 Scope
This part of IEC 62933, which is a Technical Report, describes aspects on reduction of
greenhouse gas (GHG) emissions associated with electrical energy storage systems (EES
systems), and presents current practices, research activities and related researches in each
country.
This document is intended to be used by those involved in design, development and use of EES
systems, the grids and the renewable energy sources in the grids, where various applications,
including but not limited to long term ones (peak shaving, load levelling, backup power, etc.)
and short term ones (frequency regulation, renewable energy stabilization, etc.), are considered.
The current version of this document is structured in as follows: Clause 4 describes the general
concept of GHG emissions reduction, Clause 5 describes the current practices, and Clause 6
describes academic approaches.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
battery energy storage system
BESS
electrical energy storage system with accumulation subsystem based on batteries with
secondary cells
Note 1 to entry: The battery energy storage system includes a flow battery energy system (IEC 62932-1:2020,
3.1.15).
Note 2 to entry: Batteries are defined in IEC 60050-482:2004, 482-01-04, and secondary cells are defined in
IEC 60050-482:2004, 482-01-03.

3.2
grid
particular installations, substations, lines or cables for the transmission and distribution of
electricity
Note 1 to entry: The boundaries of the different parts of this network are defined by appropriate criteria, such as
geographical situation, ownership, voltage, etc.
Note 2 to entry: The term grid is used as in 3.2 unless otherwise defined.
[SOURCE: IEC 60050-601:1985, 601-01-02, modified – in the term, “grid” has replaced “electric
power network” and note 2 has been added.]
3.3
greenhouse gas reduction
GHG reduction
calculated decrease of GHG emissions between a baseline scenario and the project
4 General
The promotion of renewable energy (RE) is a global agenda, and in particular the mass
introduction of solar and wind power is in progress. IEC White Paper “Electrical Energy
Storage [1] ” states that “Electrical Energy Storage, EES, is one of the key technologies in the
areas covered by the IEC. EES techniques have shown unique capabilities in coping with some
critical characteristics of electricity, for example hourly variations in demand and price. In the
near future EES will become indispensable in emerging IEC-relevant markets in the use of more
renewable energy, to achieve CO reduction and for Smart Grids”. Thus, this document tries to
address GHG (e.g. CO and others) emissions reduction associated with EES systems. For
example, EES systems contribute to the replacement of a number of thermal power generators
in the context of long and short duration application and grid frequency control where rapid
response and controllability as the major characteristics of EES systems are utilised (see
Figure 1).
• As renewable energy increases, some fossil fuel power plants should be shut down,
resulting in a decrease in the balancing power force.
• Frequency fluctuation becomes bigger issue because of insufficient balancing power force.
• Fast response EES systems could be a solution.
___________
Numbers in square brackets refer to the Bibliography.

– 8 – IEC TR 62933-4-200:2024  IEC 2024

Figure 1 – Actions to take against frequency fluctuation (short duration)
As more RE has been promoted, electrical energy storage (EES) systems have become
indispensable. [2] The recent key usages of EES systems, for example battery-based energy
storage systems (BESS), aimed at the GHG reduction are listed below:
NOTE The terms used in the list below and in Clause 5 and Clause 6 are sometimes different from the definitions
in IEC 62933-1, but the terms used in the cited references are used "as is" to avoid mistranscriptions in their inclusion
in this document.
• Mobile battery loaded in electric vehicles (EVs) [3]
The widespread use of battery-powered EVs potentially contributes to the reduction of GHG
emissions in the transportation sector. In addition, EVs’ contribution to GHG reductions
depends on the power supply configuration when charging the EVs.
• Store surplus energy of photovoltaic (PV) power [4] [5]
If abundant PV will be installed in a grid, its surplus energy is suppressed to maintain
stability of the grid and to make effective use of excess energy. Without BESS, such
curtailment means waste of energy. The BESS provides storage function of energy and
addresses duck curve issue (shifting the daytime energy to night time).
• Regulation/reserve for frequency control [6] [7] [13]
In the grid, regulation/reserve is used to balance supply/demand and maintain frequency.
This regulation/reserve is supplied by a fossil fuel power plant and a pumped storage hydro
power plant. BESS also has a potential to provide the regulation/reserve. EES systems can
potentially replace the balancing and system services of a fossil fuel power plant and
thereby enable reduction of GHG emissions in combination with RE sources.
• Load levelling (LL) and load shift [8] [9]
One of the potential usages of BESS is load levelling (LL) and load shift. Peak demand has
traditionally been served by fossil fuel power plant, while BESS has a potential to assist the
peak demand. BESS contributes to reduction of the fossil fuel power plant (and thus
contributes to GHG emissions reduction).
• Smart grid with BESS in physically isolated grids, for example in islands [4] [10] [11]
100 % RE power supply is possible on isolated islands by using BESS.
• Miscellaneous assist by BESS to promote RE [12] [13]
GHG can be reduced by BESS, since BESS enhances the introduction of RE. Distributed
BESS improves the congestion of grids and compensates the imbalance caused by RE.
Dynamic stability can be improved by a virtual synchronous generator which is realized by
a BESS with a special power conversion system (PCS). Emergency power supply by diesel
generators can be replaced by the BESS.

The tasks that are desired to be solved are:
– cost down of the BESS;
– development of more effective operation of the BESS which realizes the multiple purpose
use;
– GHG emissions throughout the lifecycle of BESS.
In the following clauses, this document describes the current practices in Clause 5 and the
academic approaches in Clause 6.
As for the current practices of Clause 5, it was not possible to confirm the practices aimed at
contributing directly to GHG emissions reduction at the time of drafting this document. Therefore,
the practices are picked up that are supposed to contribute to GHG emissions reductions.
As for Clause 6, this field is at the academic stage because it is necessary to estimate GHG
emissions reduction by combining the following various conditions:
• current power supply configuration;
• power supply configuration assuming replacement by EES systems;
• usage of EVs and EES systems;
• type of energy storage technology.
In Clause 6, representative examples of papers or articles that are expected to contribute to
GHG emissions reductions are given.
Furthermore, the life cycle of EES systems, as shown in IEC TS 62933-4-1, consists of four
stages: acquisition, installation, operation and maintenance, and disassembly. The product
state is out of the scope of the IEC TS 62933-4 series since it is before acquisition or after
disassembly. The current version of IEC TS 62933-4-1 describes the “operation and
maintenance” stage of the EES systems. For the “acquisition”, “installation” and “disassembly”
stages, the current version of IEC TS 62933-4-1only describes the potential for GHG emissions
as indicated below.
• Acquisition:
GHG emissions occur when purchasing the products “battery”, “PCS”, and “auxiliary
equipment” that make up the EES systems and transporting them to the location where the
EES systems are installed. Acquisition requires communication and GHG emissions
associated with those social activities. There is also GHG emissions from the transport
sector in the transportation of the products that make up the EES systems.
• Installation:
There are GHG emissions associated with the use of assembly equipment on site. There
are GHG emissions associated with the use of test power sources on-site.
• Disassembly:
There are GHG emissions associated with the use of disassembly equipment on site.
Furthermore, the environmental aspect is required to be described in IEC documents, as stated
in IEC Guide 109 and ISO Guide 64.
For more information about GHG emissions/sinks inventory, there are various documents
available. For example, there is one compiled by the United States Environmental Protection
Agency. [14]
The information in Clause 5 and Clause 6 is obtained using the example presented in Annex A,
which is considered useful for the further development of this document in a future edition.

– 10 – IEC TR 62933-4-200:2024  IEC 2024
5 Current practices of EES systems usage in relation to GHG emissions
reduction
5.1 General
Clause 5 describes the cases in each country, focusing on cases aimed at contributing to GHG
emissions reduction. However, no case has been identified that directly contributes to GHG
emissions reduction at the time of drafting this document.
NOTE The terms used in Clause 5 are sometimes different from the definitions in IEC 62933-1, but the terms used
in the cited references are used "as is" to avoid mistranscriptions in their inclusion in this document.
5.2 Korea case (KR)
5.2.1 Case name
Korea case.
5.2.2 Overview
An electrical power company in Korea started the development of EES systems technologies
for the frequency regulation (FR) service in 2014 (see Figure 2 and Figure 3).
At the demonstration stage, an EES system was installed at Jocheon substation on Jeju Island
that consists of four PCSs with a rated power of 1 MW and four Li-ion batteries with 2 MWh
capacity. A control system of the Jocheon EES system was repeatedly simulated and improved,
and then its applicability as the fundamental control system for a FR EES system was verified.
The subsequent FR EES system started to be developed in units of 4 MW PCSs and with the
fundamental control system.
At the expansion stage, two large-scale FR EES systems were installed at Seo-Anseong and
Shin-Yongin substations, the rated power of which are 28 MW and 24 MW, respectively. The
former is for the primary frequency control (G/F, governor free) and the latter is for the
secondary frequency control (AGC, automatic generation control).
After that, 11 additional FR EES systems were installed up to 2017, and as of 2019, a total of
13 FR EES systems have been in commercial operation in different places (i.e., substations).
Their total rated power is 376 MW based on the rated power of the PCS and the largest rated
power of the PCS is 48 MW.
Figure 2 – Current FR EES sites in Korea

Figure 3 – FR EES system commercial operation
5.2.3 View points
The fundamental control system of FR EES systems has a basic unit of 4 MW and controls four
1 MW PCSs, and it is called frequency regulation controller (FRC).
At first, the FRC measures the system frequency. Based on this, it calculates the required output
of each PCS and sends a control signal to each PCS, and then the PCS discharges or charges
the output from the battery according to the received control signal.

– 12 – IEC TR 62933-4-200:2024  IEC 2024
Generally, FR EES systems consist of many PCSs controlled by several FRCs. In order to
control them appropriately, a control system at the upper layer called FRC master (FRCM) was
developed. The FRCM monitors the status of individual FRCs and cooperates with the control
function, if required. Under any situation where some FRCs are faulted, in order to satisfy the
original requirement, the FRCM can make the available (or remaining) FRCs be operated for
more output.
The FR EES systems in the Korea case output the assigned power within 200 ms, from the time
when the system frequency is measured.
5.2.4 Economics
In the past, the FR service in KOREA was mainly provided by coal-fired power generators that
have relatively inexpensive cost and proper response ability.
They were outputting less power (0,95 p.u.) than their own rated power, and the remaining
power (0,05 p.u.) was in stand-by at ordinary times and was only used at times when he FR
service was required.
The amount corresponding to the remaining power (0,05 p.u.) was solved by other generators
which have more expensive cost; as a result, the total operation cost of whole grids used to
increase.
EES systems can replace the conventional means for FR service, coal-fired power generators.
In other words, an FR EES system makes the coal-fired generators able to output their rated
power and also makes generators with expensive cost be less operated.
It is expected that this representative merit of FR EES systems results in the decrease of the
total operation cost for the whole system.
5.2.5 FR EES systems GHG emissions reduction calculation formula
For the purpose of frequency regulation, pre-designated existing generators such as coal, oil,
gas and so on, usually operate in a stand-by way during an entire year and then consume fuels
as much as allocation outputs according to the types of generator units. If EES systems are
replaced with them, reduction in CO emissions can be expected because they are operated
only if necessary. Therefore the estimation of GHG reduction during a year can be quantified
as follows.
T n T
GHG y P t* x− P t*ηγ*
( ) () ()
∑∑ ALLOi i ∑ ESS in,out ESS
ti11 i 1
Subj. to
n
PP− =0
∑ ALLOi ESS
i=1
where
GHG(y) GHG reduction amount a year,
Pt allocation output (kW) according to generator types,
()
ALLOi
P t charging and discharging output of EES system,
()
ESS
x CO emission coefficient of existing generators,
i 2
= = =
=
CO emission coefficient of EES system,
γ
ESS 2
I generator types,
t time interval,
T target year,
η charging and discharging efficiency (loss) of EES system.
in,out
In the above formula, the difference between the output of the fossil fuel generator for FR
replaced by the EES system and the carbon emission coefficient multiplied by the loss
(reduction) generated by the charging and discharging power of the EES system and the
charging efficiency of the EES system are proposed as the GHG reduction. Note that γ can
ESS
be a variable depending on the operation mode.
5.2.6 GHG emissions reduction
5.2.6.1 General
Based on the analysis of power generation source and load data, the amount of green house
gas reduction was calculated by each scenario Case 1 (see Figure 5) and Case 2 (see Figure 6),
in order to estimate the amount of GHG emissions reduction of the FR EES system. Since the
amount of GHG reduction was calculated on the assumption of Case 1 and Case 2, the amount
of GHG reduction can be estimated with actual data in the future.
5.2.6.2 Power generation sources
On the basis of the 2019 organization (draft) of electric power sources as part of the fifth basic
plan for electric power supply in Korea, the following power generation sources were organized
for this case study, see Table 1 (excluding hydraulic and pumped storage generation and other
new and renewable generation sources).
Table 1 – Example of the power generation sources for each fuel source
Type Total capacity Percentage Carbon emissions
(MW] (%) (kg)/1 MWh
LNG 32 251 31,6 46,62
Soft coal 32 644 32,0 153,07
Anthracite coal 725 0,7 172
Heavy oil 3 258 3,2 82,69
Nuclear power 32 162 31,5 0
Others (by- 936 0,9 109,56
product gases)
Total 101 996 100,0
5.2.6.3 Basic load data (prior to EES system operation)
The reference to “data of estimated demands for each 5 min” was reported by Korea Power
Exchange.
The following graph shows the load data for every 5 min for the first week of April, 2020 (for the
whole week), see Figure 4.
– 14 – IEC TR 62933-4-200:2024  IEC 2024

Figure 4 – Data of loads for every 5 min during the first week of April (one week)
• Frequency scenario (assumed)
On the assumption of the regular distribution that the average was 60,0 Hz and the standard
deviation was 0,02 based on actual domestic frequency data, the following two frequency
scenarios (Case 1, Case 2) were created and applied (see Figure 5 and Figure 6):

Figure 5 – Frequency scenario at intervals of 5 min (Case 1)

Figure 6 – Frequency scenario at intervals of 5 min (Case 2)

• FR EES system charging/discharging scenario
EES system configuration: 376 MW / 94 MWh (4C).
FR EES system operation algorithm in the normal status (see Figure 7).

Figure 7 – FR EES system operation algorithm in the normal status
In consideration of the operation algorithms above, the EES system charging/discharging
scenarios for each frequency scenario of Case 1 and Case 2 were created as shown in Figure 8
and Figure 9:
Figure 8 – EES system charging/discharging scenario at intervals of 5 min (Case1)

– 16 – IEC TR 62933-4-200:2024  IEC 2024

Figure 9 – EES system charging/discharging scenario at intervals of 5 min (Case2)
The EES system charging/discharging scenarios determine the final load for the two cases on
the basis of the basic load.
5.2.6.4 GHG emissions reduction for FR EES system
EES systems can maintain power quality such as voltage and frequency, by supplying or
absorbing power from or into EES systems when necessary. In addition, the penetration of
renewable energy requires more frequency control capability in the power system. EES systems
can be used to enhance the capability through the control of charging and discharging from
network operators, so that the imbalance between power consumption and generation is
lessened.
For the purpose of frequency regulation, pre-designated existing generators such as coal, oil,
gas and so on, usually operate in a stand-by way during an entire year and then consume fuels
as much as the allocation outputs according to the types of generator units which are 888 tonnes
CO /GWh for coal, 29 tonnes CO /GWh for nuclear, and so on according to the WNA Report
2e 2e
2011 [15]. If EES systems are replaced with them, reduction of CO emission can be expected
because they are operated only if necessary. Therefore the estimation of GHG reduction during
a year can be quantified in the formula given in 5.2.5.
If the existing plants of coal generation used for frequency regulation are replaced by EES
systems, the CO emissions can be reduced by avoiding stand-by operation of coal generator.
The amount of GHG reduction during a year can be calculated by:
T n T
GHG y P t* x− P t*ηγ*
( ) () ()
∑∑ ALLOi i ∑ ESS in,out ESS
ti11 i 1
Here, the total amount of the EES system is assumed as 1 000 MW(4 000 MWH) and the
efficiency of the EES system is also 85 % for frequency regulation application. The allocation
unit of nuclear, which does not emit CO , is used as the one for the EES system.
-6
P / year = 365 d × 1 000 MW × 24 h × 888 kt/MWh × 10 = 7 779 kt
ALLO
i
-6
P t η /year = 365 d × 4 000 MW × 29 kt/MWh × 10 × 85 %= 36,3 kt
()
ESS in,out
GHG(y) = 7 742,9 kt
= = =
=
5.3 Cases in Japan (JP)
5.3.1 Case name
Japan case.
5.3.2 Overview of the case
In Japan, large capacity BESS such as sodium sulfur (NaS) battery systems, redox flow battery
systems, and lithium-ion battery (LiB) systems have been utilized at consumer sites as load
levelling and emergency power supply/voltage dip measures. By doing this, they discharge at
the peak in the daytime with electricity charged with a relatively environmentally friendly power
source at night, and they use charged electricity as an emergency power source without using
the on-site fossil fuel system generator at the time of power failure or dips.
Recently, as measures against the negative impact of massive penetration of renewable energy
surplus
(RE), attention has been paid to utilizing BESS for system frequency fluctuation, store
power of RE, measures against voltage of distribution lines, etc. Demonstration projects at
substations and customer sites have been advanced. In this way, the adjustment power of the
thermal power plant on the grid side for frequency fluctuation can be replaced with the BESS.
In addition, the surplus power of the RE can be stored by the BESS without suppressing the RE
output. These measures have been verified, and institutionalization for practical use is in
progress.
There is a possibility that the power source derived from fossils will be reduced and these will
lead to GHG reduction.
5.3.3 Utilization of conventional BESS
Japan's peak demand is sharp throughout the four seasons, including hot and humid in the
summer and severe cold in the winter. In addition, Japan relies on imports from overseas for
most energy resources. For this reason, load levelling has been required for a long time. For
this purpose, researches for energy conservation and new energy have been promoted. Since
1980, large-capacity BESS have been developed nationwide. As a result, the development and
commercialization of BESS has advanced. These BESS have been applied for single or multiple
purposes such as load levelling, emergency power supply, and voltage dip countermeasures.
With these applications, electricity charged by a relatively environmentally friendly power
source is discharged as necessary. For example, it is used as an emergency power source
without using fossil fuel-based private power generation facilities in the event of a power outage
or voltage dip (see Figure 10).

– 18 – IEC TR 62933-4-200:2024  IEC 2024

Figure 10 – Application of behind the meter
5.3.4 Advanced use of BESS
Large-scale penetration of renewable energy such as solar power generation and wind power
generation has caused problems such as frequency fluctuations, surplus power, and distribution
line voltage fluctuations (see Figure 11).

Figure 11 – Problems caused by large-scale penetration of renewable energy
The spread of renewable energy increases frequency fluctuations. As a countermeasure, both
the grid side and the customer side are considering the use of storage batteries to stabilize the
power system, such as frequency fluctuation mitigation (see Figure 12).

Figure 12 – Background of BESS utilization in the power system
5.3.5 Application example on the grid side
In Japan, many projects are being carried out on the utilization of BESS on the grid side, and
representative examples are introduced as follows (see Figure 13, Figure 14 and Figure 15).

– 20 – IEC TR 62933-4-200:2024  IEC 2024

(SOURCE: IEEJ Technical Report No 1403:2017 [19] )
Figure 13 – BESS for reducing grid frequency changes at Nishisendai substation (S/S)

(SOURCE: Hokkaido Electric Power Co, Inc. )
Figure 14 – Large BESS demonstration at Minamihayakita substation (S/S)
___________
Reproduced from IEEJ Technical Report No 1403:2017, with the permission of Tohoku Electric Power NW.
Reproduced with the permission of Hokkaido Electric Power Co, Inc.

(SOURCE: IEEJ Technical Report No 1403:2017 [19] )
Figure 15 – Energy shift demonstration by large BESS at Buzen battery substation (S/S)
5.3.6 Application example on the demand side
Supply and demand adjustment such as frequency fluctuation is usually done by the system
side, but supply and demand adjustment can be similarly made by increasing or decreasing the
load on the demand side (negative watt / positive watt). As a demonstration test, an aggregator
that bundles BESS, generators, loads, and the other system components on the demand side
adjusts supply and demand according to system commands (see Figure 16).

Figure 16 – Role of aggregator for demand response (DR)
___________
Reproduced from IEEJ Technical Report No 1403:2017, with the permission of Kyushu Electric Power NW.

– 22 – IEC TR 62933-4-200:2024  IEC 2024
In supply-demand adjustment, the certainty of negative watt and positive watt is required. The
requirements are confirmed in a demonstration test on the customer side utilizing the high
speed and high precision controllability of the BESS (see Figure 17).

Figure 17 – Virtual power plant (VPP) demonstration example
By utilizing the BESS for supply and demand adjustment, it becomes possible to reduce or stop
the thermal power generator which had to perform partial load operation or standby operation
as a conventional adjustment force. This will reduce fossil power sources and reduce GHG
emissions.
Also, when there is a surplus of renewable energy, the power generation output will be
suppressed. By storing and using this surplus power in a BESS, environmental friendliness is
improved.
5.3.7 Examples of consideration of GHG reduction by EES systems
A first order assessment of the environmental effects indicates that the introduction of BESSs
increases GHG emissions by the amount of charge-discharge losses if the energy source is
carbon based, and not solar or wind. But because batteries can change the time energy is taken
from and released back to the grid and also the time it is used locally there, significant economic
and GHG benefits can be realised especially through the coordination of supply and demand.
An example of this is found in the Kyushu region of Japan where there are many PV installations.
In Kyushu PV power generation output has been curtailed according to supply and demand
conditions. Modelling and simulations were carried out with the assumption that industrial and
commercial users will install BESSs for the purpose of reducing the maximum power and
contract demand to reduce electricity costs, and also that PV owners will install BESSs in order
to increase revenue from sales when the feed in premium (FIP) system is introduced.
For the case where the total power supply cost is minimized in the energy chain, CO emissions
were calculated both before and after the BESS was installed, and the amount of reduction was
calculated from the difference (see [18] for details).
CO emissions were reduced from 26,7 million tons/year to 25,8 million tons/year by the
introduction of BESSs, and the reduction rate in this region was 3,3 %.

The following is an overview of the simulation method.
: Minimizing the total cost related to thermal power and EES system
OBJ fixc i⋅ CAP i+ u+ c⋅ x⋅ F f , t
() () ( )
{ }
...