The Members of European Parliament (MEPs), on March 30, 2023, voted in favour of proposed European Union’s (EU) revisions to legislative framework on fluorinated gases (F-gases) emissions with an aim to steeper phase-down of hydrofluorocarbons (HFCs) on the EU market from 2039 onwards, and a full HFC production and consumption phase-out by 2050. The next step will be negotiations with the EU Council to finalise the legislation.
Earlier in March 2023, the European Parliament’s Committee on Environment, Public Health and Food Safety (ENVI) voted in favour of the same to accelerate innovation in, and the development of, more climate-friendly solutions and to provide certainty for consumers and investors. These revisions prohibit the availability of single market of products containing F-gases and the use of F-gases for sectors where it is technologically and economically feasible to switch to alternatives to F-gases, such as electrical switchgear, refrigeration, air conditioning, and heat pumps.
F-gases, which include HFCs, perfluorocarbons (PFCs), sulphur hexafluoride (SF6) and nitrogen trifluoride, are a category of manmade gases used as electrical insulation solution for power systems in transmission and distribution (T&D). The most damaging is SF6 which has a Global Warming Potential (GWP) 25,200 times greater than carbon dioxide (CO₂).
Reducing the use of F-gas has been a focus area of EU since 2006 when the initial regulation was published. Revisions to the initial legislation followed in 2015 when a deadline of 2030 was set for cutting the region’s F-gas emissions by two-thirds compared with 2014 levels. On April 5, 2022, the EC proposed revisions to F-Gas emission regulations with gradual phase out. The European Network of Transmission System Operators for Electricity (ENTSO-E) and its transmission system operator (TSO) members (representing 35 countries) have endorsed the objective of proposal to reduce f-gases emissions and are committed to contributing to achieving climate neutrality.
The recent developments have put the spotlight on the deployment of SF6-free technology in T&D networks. While several applications have been developed over the years and available in the market, there are very few vendors offering such solutions and the application has been few and far in between. The latest regulation is expected to accelerate investments in building manufacturing capacity as well as in deployment of such products in transmission.
Revised F-gases emission regulations and related concerns
The recent regulatory proposal focuses on preventing additional emission and leakage from equipment also stimulate innovation and develop green technologies by improving market opportunities for alternative technologies and gases with low GWP. Once finalised and passed, the new revisions will stipulate more restrictions on using F-gases in grid technologies and ban using F-gases in switchgear with a GWP of more than 10 by 2026 to 2031 (high voltage), depending on the voltage of the switchgear. For instance, the new revisions stipulate the installation and replacement of medium voltage electrical switchgear up to 24 kV with GWP of more than 10 or GWP of 2,000 or more from January 1, 2026. Similar restrictions will be applicable to switchgear ranging from 24 kV to 52 kV voltages from January 1, 2030. Further, these restrictions will be applied on high voltage switchgear ranging between 52 kV to 145 kV from January 1, 2028 and that at voltages of more than 145 kV from 2031 onwards.
To accelerate energy transition and renewable energy integration, TSOs are already struggling with delays in grid development due to long permitting processes, changes in the environmental requirements and lack of public acceptance. The new regulation with ambitious targets not matched by realistic implementation approach can further add on to this challenge. TSOs use SF6 in several applications., in high voltage (52 kV to 170 kV) and extra-high voltage (above 245 kV), such as switchgear, instrument transformers, gas insulated substations (GIS) and gas-insulated transmission lines (GIL). Any barrier to procurement process or delay in the expansion or repair of such equipment, poses critical risks to the stability of the grid to ensure secure electricity supply and risks jeopardising decarbonisation targets. TSOs have been undertaking substantial efforts with suppliers to pilot alternative solutions and phase down the use of SF6 in their grid operations. However, the roll-out of a reliable and significantly more environmentally friendly SF6 solutions for the different voltage levels is a highly complex process which requires technical readiness and quality proofing to ensure smooth and dependable grid operation.
For this reason, ENTSO-E urged regulators to include explicit exemptions for spare parts and for the extension of existing assets. They have recommended to maintain the possibility of developing technical solutions within a range (10<GWP<2,000) for enhanced market availability and for enabling quickest implementation of alternatives. This will ensure security of current and future onshore and offshore applications and equipment.
Another concern is ban on spare parts. The ban on placing SF6-containing products and equipment on the market should not prevent the possibility of acquiring or using SF6-containing spare parts to repair existing SF6-containing equipment, which has an expected lifetime of over 50 years. To ensure a safe power supply, TSOs need to be allowed to maintain their existing SF6 equipment until their technical end-of-life has been reached. This will ensure reduction in repair time to a minimum. Any delay in timely repair of equipment can weaken the electrical system and may cause significant redispatch costs and prevent renewable energy sources from being injected into the grid. Besides, in the case of SF6 leaks, early acting is essential to minimise emissions. Therefore, spare parts need to be quickly available to conduct the necessary repairs.
Hence, exemptions should be unambiguously applicable and allowed until the end of the technical life span of the equipment. If this is not done, it will result in the production of waste, delays in the grid development needed for the energy transition, and disproportionate costs due to the premature replacement of electrical equipment.
Also, in the past, TSOs have been supporting the development of SF6-free technological alternatives, which are promising for the reduction of the global carbon impact of high and extra-high voltage electrical equipment. ENTSO-E suggests an enhanced market availability of technologies is needed. Thus, it should be essential for any new technology to pass the required certification tests and at the same time demonstrate competent performance in real service i.e., pilot equipment under real operating conditions for 3 years should be considered. Also, the risk of dependency on one solution not yet fully tested for high voltage applications needs to be avoided.
Against this backdrop, in the latest round of innovation, technology providers have been working on finding eco-efficient alternatives to SF6 in GIS substations while retaining their technical performance. The key technical parameters for an insulation gas for use in switchgear are its dielectric strength and arc-quenching capabilities. Other equally important properties are low boiling point, low toxicity, stability, low flammability, zero ozone depletion potential (ODP) and very low GWP. Lower GWP means lower CO₂ equivalent emissions throughout the life cycle of the equipment.
Eco-efficient alternatives to SF6
Based on their respective research and development (R&D) in this area, the top three technology providers in the industry have developed their own proprietary eco-friendly GIS products, which deploy low GWP alternatives to SF6. While GE calls it g3 (g-cube: green gas for grid) gas, Hitachi Energy uses the EconiQ™ trademark and Siemens markets it under the ‘Blue’ portfolio. All the three technology providers have implemented multiple projects or prototypes (mostly in Europe) using their respective eco-efficient alternatives to SF6 in medium voltage (MV) and HV GIS projects.
In 2014, GE had developed a breakthrough technology that replaces SF6 for HV application with g3. The g3 mixture is based on 3M Novec 4710 molecule [trademark compound of 3M registered accordingly to European REACH process for chemicals; fluorinated nitrile C4F7N (4-10%vol)] with a carefully balanced percentage of carbon dioxide (CO2, 90-96%).
GE pitches g3 as an environmentally friendly alternative to SF6 that provides several technical, environmental and financial advantages. Presently, the commercially available for applications ranges from GIS up to 145 kV (-25°C), GIL and gas-insulated circuit breaker (GIB) up to 420 kV (-25°C) and air-insulated switchgear (AIS) current transformers (CTs) up to 245 kV (-30°C). The company is aiming to offer SF6-free GIS up to 420 kV, dead tank and live tank circuit breakers up to 550 kV, as well as instrument transformers up to 420 kV between 2023 and 2025.
Notably, the EC has supported GE in accelerating the development of its SF6-free portfolio, particularly for higher voltages. For instance, in 2020, the EC awarded EUR2.2 million to GE Grid Solutions, through the L’Instrument Financier pour l’Environnement (LIFE) climate action programme, to facilitate the development of a SF6-free, 420 kV GIS circuit-breaker. More recently in August 2022, the EC awarded EUR3 million to GE Grid Solutions for the development of SF6-free, 245 kV GIS substations for onshore and offshore applications.
In 2022, the company unveiled the world’s first 420 kV, 63 kA g3 GIS circuit-breaker prototype, which is expected to be commercially available this year. It is fully type-tested; applicable in the same environmental conditions and at the same ambient temperature ranges as SF6; compatible with switchgear material; fits with indoor and outdoor applications down to -30°C; and is nontoxic and falls in the same safety class as SF6. Further, g3 HV equipment features the same dimensional footprint as SF6 equipment. Notably, g3 has 98 per cent less impact on GWP as compared with SF6 gas. While one kilogram (kg) of SF6 gas will have 23,500 kg of CO2 emissions, one kg of g3 will have only 400 kg of CO2 emissions. Other environmental benefits include safe and easy handling for filling and topping up; no impact on ozone depletion; not inflammable; and there is no risk of soil pollution. Financial benefits could be derived as utilities could qualify for tax reductions or incentives related to greenhouse gas (GHG) emissions reduction.
Siemens’ Blue portfolio
During 2016, Siemens had developed a breakthrough technology that replaces SF6 for HV application using its vacuum technology and so-called clean-air technology up to a voltage of 145 kV. With this technology, a vacuum interrupter unit performs the switching and arc extinguishing activities. Technically processed and purified air (free of humidity) with a mixing ratio of 80 per cent N2 to 20 per cent O2—called clean air—provides the insulation for the current-carrying conductors inside the metal-encapsulated GIS. Presently, the commercially available for applications ranges from GIS up to 145 kV, dead tank and live tank circuit breakers up to 145 kV, as well as instrument transformers up to 420 kV.
With the new CBs and switchgear, Siemens is extending the use of vacuum switching technology up to a rated voltage of 145 kV, a rated short-circuit breaking current up to 40 kA, operating temperatures from -55°C up to +55°C. This makes it suitable for both outdoor and indoor applications. The GWP of the switching and insulation technology is zero. The lower insulating capability of natural gases results in slightly larger dimensions compared with GIS with SF6. However, power transmission efficiency in practice remains as high as before. Vacuum switching technology provides advantages for the operator including easier handling during transport, installation, operation, maintenance and recycling. Further, there is also no obligation to report the volumes of gas used. It has already launched the 8VM1 GIS of 72.5 kV, which is especially designed for application in offshore wind (OSW) turbines using the above technology.
Recently, Siemens’ Blue portfolio also added trench clean air instrument transformers up to 420 kV. This is based on proven trench SF6 designs but uses clean air as the insulation medium. The first switchgear for primary technology for line voltages up to 12 kV was launched by Siemens in 2018 as type 8DAB 12. This was followed by variant 8DJH 12 in 2019 for the secondary distribution level. The NXPLUS C 24 unit with a rated voltage of 24 kV was introduced in 2020. As a next step, Siemens plans to complete its F-gas-free MV portfolio with products up to the 36 kV voltage level.
In 2021, Siemens Energy bagged a contract from Finnish TSO Fingrid for delivery of 10 bays of SF-6- free GIS as part of the TSO’s efforts to modernise the 110 kV-switchgear in Virkkala substation in Lohja, located 60 km west of Helsinki. Siemens delivered GIS of 8VN1 type which uses vacuum interrupters for switching and clean air as insulation medium.
Siemens Energy is investing over EUR60 million in a new factory, where SF6-free vacuum interrupters will be manufactured within the company’s switchgear plant. The new facility is scheduled start production in 2023.
Hitachi Energy’s EconiQ portfolio
Hitachi Energy’s new eco-efficient switchgear uses an SF6-alternative gas mixture, EconiQ™ (formerly known as AirPlus™), as the insulation medium for HV switchgear and has been proven to more than halve CO2 equivalent emissions throughout the total lifecycle. The use of EconiQ will help avoid regulatory procedures related to SF6 such as maintaining inventory, special requirements in gas handling, filling and decommissioning of the equipment as well as savings made in SF6-related taxes, which are applicable in some countries.
In November 2022, Hitachi Energy won a contract from German Dutch TSO, TenneT, for supply of world’s first SF6-free 420 kV GIS from its EconiQ portfolio. Hitachi Energy will provide a modular prefabricated grid connection solution at a key node at TenneT’s German power grid by 2026. This eco-efficient innovation remains similar in size while being 100 per cent as reliable as the conventional GIS solution based on SF6. This installation will effectively avoid the addition of nearly 2,300 kg of SF6.
Significantly, in December 2022, Hitachi Energy bagged another order from UK’s National Grid to deliver EconiQ 420 kV GIS and GIL to strengthen the London Power Tunnel (LPT), a key infrastructure project that will ensure reliable, clean electricity supply for the capital city, by 2027.
The way forward
Technology providers have been successful in developing alternative technologies that can significantly reduce GHG emissions in transmission. This gives confidence to TSOs the that manufacturers can deliver new alternatives, potentially even more sustainable and efficient. That said, replacing the existing infrastructure will remain a challenge as the proposed phase down interferes with their existing planning and future investments. Net net, while Europe is headed in right direction towards decarbonisation, taking all stakeholders along is highly critical for seamless implementation.