How should spent medium and high voltage (MV and HV) equipment be properly recycled? It depends upon whether Sulphur Hexafluoride (SF6) gas is involved in the process.SF6 is a greenhouse gas used as an insulator and breaker medium within switches, circuit breakers, and other MV and HV electrical transmission and distribution equipment. While SF6 offers advantages in technological applications, it becomes a hazardous waste at the end of its life. Governments worldwide require strict adherence to equipment disposal regulations and impose severe penalties for noncompliance.
When electrical equipment reaches the end of its life, it contains solid and gaseous SF6 decomposition by-products as HF, SO2, SO2F2 and SOF2, which are toxic and corrosive. Molecular sieves placed inside SF6 compartments absorb most of these gaseous by-products. But a small amount of solid powder by-product can sometimes accumulate.
Why does the electrical industry use SF6?
Life-cycle analysis of SF6 and SF6-free technologies has shown that they have similar carbon footprint profiles. However, SF6-based technology has definite advantages in terms of safety, ease of maintenance, and operational continuity. In addition, SF6 allows for compactness and is effective in harsh environments. Forecasts indicate that SF6 consumption may grow 50% by 2030 within the electrical industry.
How does SF6 affect the environment?
In its pure state, SF6 is not a dangerous material, because it’s not an ozone-depleting substance, nor is it poisonous to human beings, plants or animals. However, it poses a threat as an enabler of global warming. A high Global Warming Power (GWP) classifies SF6 as a greenhouse gas; the Kyoto Protocol requires that nations around the world monitor its use.
SF6 has the highest GWP of all the gasses and has an atmospheric life span of 3,200 years. But due to the effective closed-cycle reuse process and aggressive recycling approach of the electrical industry, SF6 remains one of the least harmful technological solutions and is the lowest contributor to global warming of the greenhouse gases.
The right process: SF6 recycling for MV and HV equipment
Following the proper SF6 end-of-life process helps protect the environment and delivers a 98% recycling rate, making the substance available for reuse in electrical equipment. Compliance with regulations also contributes to carbon emission reduction.
Launching an SF6 disposal initiative begins by auditing equipment that is near its end of life; the audit is the basis for developing a disposal and recycling plan.
Electrical equipment owners select a trained and certified disposal/recycling partner to manage the process.
When dismantling equipment, waste managers segregate and store SF6, copper, aluminum and iron in separate containers. Using a vacuum pump and task-specific valves, operators can safely extract the SF6.
At a recycling center, purification processes remove water, air, and the remaining small quantities of toxic and corrosive by-products.
In accordance with national or regional regulation, only licensed, authorized hazardous waste managers may handle, transport, recycle or destroy SF6. Pickup, transport and dismantling of obsolete electrical equipment is subject to regulatory codes, with tight guidelines for documentation, labeling, packaging and safe handling.
What recycling assistance is available to electrical equipment owners?
The SF6 technology imbedded in electrical equipment is not a threat to the planet as long as electrical industry owners follow the proper closed-cycle process. Owners frequently subcontract the hazardous waste end-of-life process. In fact, involving a knowledgeable, experienced partner with a detailed end-of-life program in place eliminates worry and risk for the electrical equipment owner.