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Tan, E.S.; Pua, F.L.; Verayiah, R.; Syazalina, N. Methodological Improvement in SF6 of Malaysia's National Inventory. Encyclopedia. Available online: https://encyclopedia.pub/entry/45471 (accessed on 13 April 2024).
Tan ES, Pua FL, Verayiah R, Syazalina N. Methodological Improvement in SF6 of Malaysia's National Inventory. Encyclopedia. Available at: https://encyclopedia.pub/entry/45471. Accessed April 13, 2024.
Tan, Ee Sann, Fei Ling Pua, Renuga Verayiah, Nurul Syazalina. "Methodological Improvement in SF6 of Malaysia's National Inventory" Encyclopedia, https://encyclopedia.pub/entry/45471 (accessed April 13, 2024).
Tan, E.S., Pua, F.L., Verayiah, R., & Syazalina, N. (2023, June 13). Methodological Improvement in SF6 of Malaysia's National Inventory. In Encyclopedia. https://encyclopedia.pub/entry/45471
Tan, Ee Sann, et al. "Methodological Improvement in SF6 of Malaysia's National Inventory." Encyclopedia. Web. 13 June, 2023.
Methodological Improvement in SF6 of Malaysia's National Inventory
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Sulfur hexafluoride (SF6) gas is one of the high global warming potential (GWP) gases regulated under the Kyoto Protocol. In Malaysia’s Biennial Update Report 3, the Revised 1996 Intergovernmental Panel on Climate Change Guidelines were followed to estimate the SF6 emissions in the country, including the time series from 1990 to 2016. The majority of SF6 emissions originate from the use of this gas in electrical equipment, where it is predominantly used in transmission switch gears, which have increased rapidly because of increasing electricity demand. SF6 gas plays a significant role in greenhouse gas emissions in Malaysia because this gas has a higher GWP than carbon dioxide.

sulfur hexafluoride greenhouse gas inventory electrical equipment

1. Overview of SF6 gas

Sulfur hexafluoride (SF6) gas has been utilized as an insulating medium for high-voltage circuit breakers since the 1950s because of its exceptional dielectric and arc-quenching properties, which stem from its high electronegativity and density. In addition, its high density has allowed the construction of smaller electrical equipment that is manageable and can bear safe high-voltage loads. However, SF6 gas usage has a few disadvantages and operational constraints. For example, maintaining the required dielectric properties means that SF6 gas needs to be kept at a minimum functional pressure. Operators must purchase additional gas to replace any leaked or lost SF6 gas, which adds to a facility’s costs. Moreover, exposure to moisture must be minimized because it can degrade the dielectric properties and cause dangerous by-products, such as hydrofluoric acid, to form from decomposed SF6 gas. Lastly, SF6 gas is a harmful greenhouse gas (GHG) that can persist in the atmosphere for up to 3200 years; 1 tonne of SF6 gas emission is equivalent to 22,800 tonnes of CO2.
Despite these concerns, SF6 has been used in electric power utilities for more than 40 years because of its remarkable electrical, thermal, physical, and chemical properties. To reduce SF6 emissions into the atmosphere, the industry continues to concentrate on improving its SF6 handling practices. Poor gas handling practices during equipment installation, maintenance, and decommissioning, as well as leakage from SF6 containing gas-insulated equipment, are the main sources of SF6 emissions. Closed-pressure equipment is prone to SF6 emissions, while emissions in sealed-pressure equipment are more apparent during the manufacturing process and disposal. Proper disposal procedures are needed to curtail leakages of SF6 gas into the atmosphere.
Typical equipment includes circuit breakers, switch gears, buses, compartments, and outdoor transformers. SF6 gas is purchased and used by utilities to top up or recharge their equipment. Therefore, leakages are common with electrical equipment, and utilities are required to recharge their equipment to make up for the SF6 gas that has escaped/leaked. Some fugitive SF6 emissions can potentially occur during/from gas handling and transferring operations, equipment operation, and mechanical failure. Over time, electrical equipment reaches the end of its service life and is then replaced rather than sent for repair because replacement is a more attractive SF6 gas mitigation strategy. Reduction of GHG are important as many countries [1][2][3] identify mitigation actions in their climate change policies for decarbonization.

2. Need for an Improvement Plan for SF6 Emission Estimation for the National Greenhouse Gas Inventory

In Malaysia’s Biennial Update Report (BUR3) to the United Nations Framework Convention on Climate Change (UNFCCC), SF6 gas is not considered a key category because the total emissions in this sector do not have a significant influence on the country’s total inventory of GHG in terms of absolute level.
The motivation for improving the national GHG inventory is to better understand the sources and magnitude of these emissions, which is essential for developing effective climate change mitigation and adaptation policies. The significant contribution of this research is the establishment of methodologies to estimate SF6 gas emissions from electrical equipment for Malaysia, which was achieved according to the requirement of IPCC 2006 Guidelines. Ultimately, this work fulfills the National Improvement Plan, which aims to uphold two main principles from the TACCC: transparency and accuracy.
Figure 1 shows the total emissions for the sector of Industrial Processes and Product Use (IPPU) for Malaysia on the basis of GHG emissions reported in BUR3 [4]. Among the various sub-categories in this sector, the use of SF6 gas is reported under the main category 2G: Other Product Manufacture and Use and within the specific sub-category 2G1b: Use of SF6 gas in Electrical Equipment. This category recorded less than 1% of the total GHG emissions for 2016. Category 2G1 is not a key category, which is why the development of a country-specific emission factor (CSEF) is not a priority because the emissions are not considered significant. However, inventory compilers need to estimate this category based on the 2006 IPCC Guidelines [5] to consistently measure the GHG emissions of the country by using the same basis for comparison.
Figure 1. Total GHG emissions for IPPU for Malaysia [4].
Similarly, in the BUR3 report, all GHG are estimated using the 2006 IPCC Guidelines, except for SF6 gas used in 2G1 Electrical Equipment, which requires the adoption of the Revised 1996 Guidelines based on limitations of activity data during that period [4]. Table 1 describes the scenario faced by the country during BUR3 reporting and evaluates it based on the SF6 emission estimation methodology available from the 2006 IPCC Guidelines.
Table 1. Status of accounting during BUR3 for sub-categories of SF6 gas methodology according to 2006 IPCC Guidelines [4].
Many sub-categories such as 2B9: Fluorochemical Production, 2C4: Magnesium Production, 2E2: TFT Flat Panel Display, and 2G2, namely, SF6 and PFCs from Other Product Uses such as military and accelerators, among others, were not accounted for because no activities occurred pertaining to those industrial processes and use in Malaysia for that duration. In addition, categories such as 2E1: Integrated Circuit or Semiconductor and 2E3: Photovoltaics under the Electronics Industry were successfully estimated using the 2006 IPCC Guidelines based on default Tier 1 methodology. Hence, the only remaining sub-category using the Revised 1996 Guidelines in the national GHG inventory is this category because inadequate data were collected, given that the newer guidelines require more detailed activity data, as will be explained in the subsequent sections. In view of this situation, Malaysia initiated the National Inventory Improvement Plan for SF6 emission estimation, concentrating on 2G1, because it is the only remaining sub-category that has yet to transition to the newer methodology of GHG emissions.

3. SF6 Sources in Malaysia

The electricity sector in Malaysia covers the generation, transmission, distribution, and sales of electricity in the country. The country has three main utility providers: Tenaga Nasional Berhad, Sabah Electricity Sdn. Bhd., and Sarawak Electricity Support Corporation (also known as Sarawak Energy). On the basis of the generation mix until the end of 2010, the total plant generating capacity is estimated at 26,265 MW, constituting 57% natural gas, 24.1% coal, 8.4% hydro, 6.4% oil/diesel, and 4.2% biomass/others [6].
According to the 2006 IPCC guidelines, SF6 gas was emitted in each phase of the electric equipment life cycle, specifically during the manufacturing, installation, use, servicing, and disposal stages. A large quantity of SF6 gas is usually used in gas-insulated transformers (GITs) in Asian countries. SF6 gas is used in the power industry because of its exceptional electrical insulation and arc-quenching properties. However, the management and handling of SF6 gas must be conducted properly because SF6 gas is a GHG with a higher global warming potential (GWP) than CO2 [7][8].
SF6 gas is also heavily used in gas-insulated substations, where SF6-insulated circuit breakers, busbars, and monitoring equipment are housed. Among the most significant use of SF6 gas is in high-voltage circuit breakers, where it serves as insulation and helps extinguish the arc from occurring when an energized circuit breaker operates. The quantity of SF6 gas emissions from electric power systems is influenced by various factors, such as the type and age of the SF6-containing equipment and the handling and maintenance operating standards followed by utility providers. With its prolonged life span and high GWP, even a small amount of SF6 gas can have a strong effect on the environment [9].
The gas is also used to detect a direct leak in an enclosed GIS substation. Indirect leak detection solutions are expensive because they require one monitoring device per gas compartment. Furthermore, the pressure/density switches that are currently used to monitor the SF6 gas compartments for safety consideration lack sensitivity for rapid leak detection. Direct detection is normally preferred and more reliable because it relies on measuring trace concentration for leaking gas in the ambient air [10].
Poor and improper handling means that SF6 emissions have the potential to occur during installation, maintenance, disposal, and equipment leakage. Leakages in closed-pressure equipment predominantly occur during the manufacturing and disposal processes, while all equipment will release SF6 gas at the disposal stage. Proper disposal procedures will be able to help reduce the emission of SF6 into the atmosphere. In the manufacture of equipment, several process steps are performed, such as installing and testing the components and equipment. During the manufacture of electrical equipment, SF6 emission is likely to occur while assembling and testing components before switch gears are obtained. To maintain the pressurized SF6 gas, the manufacturer must first conduct the volume tightness test to test the circuit breaker capability.
The next potential SF6 gas leakage can occur during the delivery of equipment or cylinders. This dry gas must be placed in the correct and safe position to ensure that no leakage occurs during the delivery process. During equipment installation, SF6 gas can also be released without proper handling or if the refilling equipment is damaged. Electrical equipment, including closed-pressure equipment, should be disposed of meticulously. This equipment needs to be deactivated properly to reduce SF6 gas leakage into the atmosphere. Used gas can only be either disposed of or reused. This process requires qualified workers from gas producers or specialized services. The risk of gas emissions is very high if untrained parties or different groups perform this process for closed-pressure and sealed-pressure equipment [11].

4. Review of the SF6 Regulation and Policy around the World

SF6 gas contributes to the high GWP of the power and semiconductor industries. As its application increases, countries have started planning to regulate this gas in various ways.
The European Union (EU) has planned precautionary measures to decrease SF6 gas because the emissions of fluorinated gases (F-gases) doubled from 1990 to 2014 [12]. In 2014, the European Commission enacted Regulation No. 517/2014, commonly referred to as the “2014 F-gas Regulation”. The latest regulation sets requirements for products and sectors beyond the power industry and all hydrofluorocarbons; however, the following discussion focuses on the SF6 gas requirements used in switch gears. According to the regulation, electrical switchgear is defined as “switching devices and their combination with associated control, measuring, protective and regulating equipment, and assemblies of such devices and equipment with associated interconnections, accessories, enclosures and supporting structures, intended for usage in connection with the generation, transmission, distribution, and conversion of electric energy” [13]. The EU is currently reviewing the effectiveness of the F-gas Regulation and exploring options to improve it. The Commission’s proposal for a new regulation, which was expected by April 2022, includes a phase-out plan for SF6-, especially for medium-voltage applications.
The U.S. Environmental Protection Agency (US EPA) required reports on large SF6 emissions in 2009. The California Air Resources Board (CARB) and the Massachusetts Department of Environmental Protection strengthened their SF6 emission regulations, including emissions reporting standards and requirements for emission reduction. In 2009, in addition to the effort to reduce the emission rates, the US EPA established a Greenhouse Gas Reporting Program, which requires major suppliers and contributors of emissions to monitor and report their GHG emissions annually [14]. In addition, the CARB is tasked with protecting the public from air pollution and developing climate change programs. Their regulation was emulated by 14 other US states, where an SF6 phase-out program will be enforced by 2025. In 2015, the Massachusetts Department of Environmental Protection enacted a regulation to ensure that all state utilities monitor and report their SF6 emissions and inventory.
No SF6 legislation in Asia specifically targets transmission and distribution businesses. Manufacturers and importers of fluorocarbon gases are urged to minimize their production and distribution while recycling fluorocarbon gases are recycled wherever practical in Japan. Through a national GHG inventory, South Korea maintains records of its yearly SF6 emissions from the energy sector. In Japan’s Fourth Biennial Update Report, filed in January 2019, SF6 emissions declined by 83.4% from 1990 levels to 2.1 million tonnes of CO2eq in 2017. This reduction is attributed to the improvements in gas recovery and management systems within the electrical utilities sector [15]. Japan has no laws that forbid the use of SF6 gas in the power sector or that require the tracking and reporting of emissions. Instead, Japan established a voluntary action plan in the late 1990s for electric utilities and switchgear OEMs, with the goals of lowering emissions throughout the SF6 life cycle, establishing and promoting recycling, improving SF6 inventory tracking, and creating an alternative insulation technology [16].
In South Korea, SF6 emissions were about 6.8 million tonnes of CO2eq., constituting at least 1.0% of the national GHG emissions in 2016. This value implies an increase of 3810.5% compared to 1990 [17]. This significant spike in percentage was due to the rapid development of various technology manufacturing subsectors over time, which called for the expansion of the electrical infrastructure. One subsector is the semiconductor industry, which uses SF6 gas in its operations. South Korea also introduced a GHG emissions trading scheme in 2015, which also involves SF6 gas. From an emissions baseline of the 2011–2013 levels, Phase 1 (2015–2017) requires 100% free allocations for the majority of the sectors; Phase 2 (2018–2020) requires 97% of the total allowance; and Phase 3 (2021–2025) will require around less than 90% free allowances [18]. The state-owned utility of South Korea, Korean Electric Power Corporation (KEPCO), reportedly signed a contract for joint usage of an SF6 gas decomposition facility with the Korean National Railway, indicating the country’s determination to shift away from SF6 [19]. The manufacturing facility will have a production capacity of 60 tonnes per year when finished, which was anticipated in June 2022. These six decomposition facilities, which would each process 300 tonnes annually, are all being built by KEPCO. The 6000 tonnes of SF6 gas that KEPCO reportedly releases are intended to be destroyed by these facilities by 2050.
In China, according to China’s National Emission Inventory, the total amount of SF6 emissions from 2012 reached 1000 tonnes, which is more than two times that in 2005 [20], 95% of which was attributed to electrical equipment [21]. The use of SF6 gas in semiconductor production has been phased out to comply with environmental regulations, and the use of SF6 gas as a safeguarding gas in magnesium manufacturing in China was stopped in 2010. Furthermore, given recent advancements in management and technology, leaking during SF6 gas manufacturing might be insignificant. Electrical equipment continues to be the principal consumer of SF6 gas and will be the primary contributor to SF6 emissions in the future.
Limited information on SF6 emissions is available in China’s Second Biennial Update Report. However, China has shifted away from using SF6 in GIS over the past 10 years. For instance, within the 12 kV voltage spectrum, including both primary distribution and secondary distribution, they have started to shift away from using SF6 gas. While solid-insulated switchgear made up the first generation of SF6-free switchgear, the current trend is moving back to gas-insulated switchgear that uses substitute SF6 gases. China is now exploring new rules or guidelines to further cut SF6 petrol usage and emissions after the 2018 report. This approach involves a focused working group composed of utilities, oil and gas companies, and some of the top switchgear OEMs. This focused working group was established in October 2021 and is charged with investigating the application of SF6 gas in the energy sector and possible approaches for regulating SF6 and its substitutes. This working group is coordinated by China’s Energy Research Society and the Ministry of Ecology and Environment [22].
An analysis of SF6 gas emissions in Malaysia indicates that the country currently has no appropriate disposal option for reducing SF6 gas [23]. Thus, at end-of-life, all the gases are released. Although the regulations mention the emission standard, the absence of containment and disposal facilities will eventually cause problems. Malaysia pledged at the UNFCCC 21st Conference of Parties to decrease its GHG emission intensity by 35% by 2030 when compared with the GDP in 2005. On the basis of the Third National Communication and Second BUR to UNFCCC, which was submitted in September 2018, the total national emissions and removals of SF6 gas were 13,240.59 kg, which corresponds to 316.45 million kg of CO2eq in 2014 [4]. The semiconductor industry and other businesses that largely rely on gas-insulated electrical equipment are the principal producers of products that consume and emit SF6 gas.

References

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