Insulator End of Life: Recycling or Disposal

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The focus when it comes to electrical products and components has traditionally been on quality and performance in service. Increasing public awareness of environmental issues, however, has now led both manufacturers and users to pay greater attention to the overall ecological impact of these products – from extraction of their raw materials to what happens to them at their end-of-life. Methodologies such as Life Cycle Assessment (LCA), which evaluate the full environmental impact of any product from ‘cradle to grave’, are therefore becoming ever more important to this industry. Indeed, a clause similar to the one below appears more and more these days in technical specifications for insulators and other apparatus, adding an environmental dimension to past requirements that talked only about manufacturing, testing and delivery: “Suppliers are required to comment on the environmental soundness of the design and on the materials used in the manufacture of the items offered. In particular, comments should address such issues as recyclability and disposability at the end of service life.”

Support toward development of this area has come from IEC TC 111, which dealt with Environmental Standardization for Electrical and Electronic Products and Systems and worked to produce relevant Standards, including:

• IEC Standard 62430:2009, Environmentally Conscious Design for Electrical and Electronic Products, specifying requirements and procedures to integrate environmental aspects into the design and development processes for electrical products;

• IEC Standard 62474, Material Declaration for Products for the Electro Technical Industry, moving toward a standardized declaration about the environmental compliance of all materials that make up the final product;

• IEC Technical Report 62635, Guidelines for End of Life Information Provision from Manufacturers and Recyclers, and for Recyclability Rate Calculation of Electrical and Electronic Equipment, intending to provide information to recyclers so as to enable appropriate and optimized end-of-life treatment. This report also evaluates recyclability and recoverability rates based on product attributes that reflect real end-of-life practices.

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One of the aspects that most affects the environmental impact of products such as insulators and related apparatus is the strategy usually adopted at their end-of-life, i.e. disposal versus recycling. Each year, power transmission and distribution utilities generate significant quantities of waste such as epoxy, silicone and porcelain materials, especially during any projects to renew ageing infrastructure. At the moment, this kind of waste frequently ends up only in landfills. But in recent years waste management directives in places such as Europe have encouraged recovery and recycling through more restrictive use of landfills. The European Parliament, for example, has issued directives on waste electrical and electronic equipment (WEEE) stating that all such equipment must be recycled and effectively banning the disposal of such waste in landfills. Greater restrictions on electrical waste, now and in the future, mean that producers as well as users of high voltage apparatus will increasingly have to identify alternative waste-management methodologies. Similar tendencies are evident in other areas of the world as well. Basically, there are four general classes of recycling techniques:

• Primary recycling, i.e. conversion of waste into materials having properties equivalent to those of the original materials;
• Secondary recycling, i.e. conversion of waste into materials having properties inferior to those of the original materials;
• Tertiary recycling, i.e. conversion of waste into chemicals or fuels, and
• Quaternary recycling, i.e. conversion of waste into energy

Most techniques when it comes to primary or secondary recycling involve mixing some waste with virgin raw material, which is then processed as if it were all virgin. Designation as primary or secondary recycling is then really a matter of how successful this process is. Tertiary recycling refers to chemical de-composition of the material (e.g. de-polymerization into chemicals and fuel) while quaternary recycling is synonymous with incineration and utilization of the energy released. From the viewpoint of material utilization, it is usually preferable to achieve the highest level of recycling possible, e.g. secondary better than quaternary recycling. However, from an economic and resource utilization perspective, this need not always be the optimal scenario. Secondary recycling might require excessive amounts of energy and other resources (e.g. facilities, manpower, additives, additional energy, etc.) whereas quaternary recycling may be simple and not require energy or any additional resources.

Primary, secondary and tertiary recycling processes all involve collecting materials, identifying them, reclaiming the remnants and then marketing them. For this process to be justifiable economically, the value of the reclaimed materials must of course be higher than the cost needed to recycle them. For example, secondary recycling of porcelain insulators (e.g. as fillers for concrete or roads after being treated in hammer-type grinders) is possible, but not especially advantageous. As a result, most ceramic material is still disposed of in landfills with only their metal parts recycled. In the case of glass insulators, secondary recycling is more viable. Composite insulators cannot easily be dismantled and re-processed for use in new products. Cost and environmentally efficient approaches for primary, secondary and tertiary recycling are therefore not yet feasible and only the metal fittings can effectively be recycled. As a result, apart from metal recovery, quaternary recycling (i.e. incineration with recovery of energy) is presently the most effective way to treat composite insulators at their end-of-life. At the same time, it should be noted that using polymeric waste as fuel for generating power or heat benefits from the fact that these materials have a high energy content to release. Due to the massive quantities of insulators, apparatus and other line components that will need to be replaced in the near term, there will clearly be a need to find clever recycling or re-utilization options. Achieving this goal will also contribute to greater sustainability of power transmission and distribution systems as a whole.