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Are PP TPE cables more recyclable than XLPE?

A fact based study comparing market sourced MV XLPE and PP TPE insulated cables

PP TPE vs XLPE cables

On the market, there are solutions promoted as more recyclable than others, and it is often difficult to judge as analytical data are lacking.

Specifically, one of the main biases is that PP-TPE cables would be fully recyclable and XLPE ones would rather not be recyclable.

Another important aspect still to be analysed in detail is also the re-use value potential of the different cable insulation options and their fit for efficient recyclability streams.

Objective study by RISE

By staying true to our EverMinds™ ambition of accelerating action on circularity, we at Borealis commissioned this first independent study to the research institute RISE to perform an equal evaluation of the recyclability properties.

The study was conducted starting from two 20 kV cables purchased on the cable market which then got dismounted and recycled, simulating current cable recyclability practices, but also future streams where, perhaps, a better separation process of the different plastic materials will be possible.

Fact and analytical-based

Technical, environmental, and economic aspects have been considered in order to provide new valuable information to Market Operators.

These can help support and enrich the relevant European debates or specific commercial tenders issued by European Distributor Service Operators, where sustainability properties of materials have started to be analysed in more detail.

The study has been made easy to read, and it is enriched with several comparative charts and pictures.

“We have been excited to conduct this first of a kind recyclability study starting from real cables purchased on the market. By assessing in depth and comparing the recyclability properties and the environmental and economic impacts of the different materials combinations, I think we have provided a very useful starting point based on facts that the Industry can use to rightly address the dialogue related with cables recyclability and to make the best of current and future recyclability streams. ”

Senior Researcher & Project Manager, Material and Production, Department Polymer materials and composites Annika Boss

Materials, methods and performance

The plastic materials coming from the following cables are analysed in the study:
– ARP1H5EX 1×185 mm2 12/20 kV
– ARE4H5E 1×185 mm2 12/20 kV

Both the cable insulation core alone (insulation + semi-conductive layers), and the total cable plastics including the cable jacket (outer sheath) for the 2 different cable are studied in detail and their properties are compared.

The different materials mixes obtained from the two cables were shredded, milled, fine milled, and compounded together with different blending materials.

Moreover, in order to simulate repeated recycling after use, heat ageing and repeated reprocessing was performed.

Test samples were injection moulded for tensile and impact testing according to ISO 527-2 1A.

Sheets were extruded and the obtained sample specimens prepared to perform the different tests and re-use simulations.

Environmental and economic impact of applications

The study provides 14 different options on how to re-use the materials coming from the cables looking at 3 main new potential applications: cable drum, cable channel for automotive, and extruded pipe.

The climate impact, CO2 savings have been calculated for the different options.

The economic savings when using the different recycled cable plastics in different end products to replace virgin plastic have been estimated. The costs of the recycling steps were estimated from data coming from recyclers and manufacturers of shredders and milling equipment. The estimated figures also include machinery costs and operator costs.

Main findings and conclusions

1) Getting specific on cables is fundamental for a proper assessment:

🍃 The recyclability properties of plastic materials contained in cable products require in-depth analysis conducted by recyclability experts. The current recyclability practices and their practical implications like, for example, cable dismounting process, cross-contamination of materials (e.g. the carbon black contained in the semiconductive materials), or a mix of the plastics contained in the insulation and in the jacket, have to be considered carefully.

2) For the cable recyclability practices currently in use, a cable with XLPE insulation and HDPE jacket has the best fit for recyclability:

🍃 In current mechanical recyclability processes, the plastics from the insulation and the cable jacket get mixed together.

🍃 Designing the cables for recycling is important: the study shows that the best is to have the same type of polymer in the insulation and in the jacket. Thus, the cable plastics can be recycled together: various polyethylenes with different densities and crosslinked XLPE can be recycled together. If the same type of polymer is used in the core and jacket recycle them together, if not recycle them separately.

🍃 The blends with XLPE Cable plastic (insulation + jacket) have excellent impact resistance, even at low temperatures. The XLPE works indeed as an impact modifier in the obtained blends, and a new valuable polymer material is obtained!

🍃 Heat aging and reprocessing have instead mixed influence on the PP-TPE Cable Plastic blends (mix of PP-TPE insulation and PE jacket). The recyclability of these blends is precarious.

3) The economic saving when replacing virgin plastic with recycled cable plastic is estimated to be between 0,6 and 1,3 €/kg, depending on the final application and recycling methods used.

4) Beyond recyclability and circularity there are other key elements to come to a complete Sustainability assessment on cables: accordingly to the international standard IEC 621251 the summary LCA2 indicator for XLPE is 59% (avg.) and for PP-TPE is 100% (avg.), this shows how XLPE is overall a more sustainable solution

5) XLPE is excellent for recyclability and circularity, today and even more in the future:

🍃 The huge amount of XLPE in high, medium and low voltage cables already installed worldwide constitutes a significant source of valuable material for recycling after end-of- life.

🍃 The new XLPE recyclability technologies beyond mechanical recycling under development will further boost the possibilities and the value of this material for future recyclability streams.

1International standard: Environmental considerations specific to insulated electrical power and control cables

2Source: Third party LCA by Denkstatt 2021

* Based on market sourced XLPE and PP TPE cables
** Based on third party study- RISE, 2021
*** Based on third party LCA- Denkstatt 2015, review 2021: The data expressed are relative to the ARP1H5EX (PP TPE) / ARE4H5E (XLPE) 185Al 20kV cable according to HD 620-10I1 (Italy).
For other MV cables designs results (e.g. 20kV cable based on HD 620-10C, Germany), get in contact with Borealis.

Note: High deviations between the different existing methodologies can be seen. The final single score is based on the average of the Ecoscarcity and the EF weighting approach. The XLPE cable is advantageous over the PP TPE version in all cable types and regarding (case 1) 100% recycling and (case 2) one third share recycling, one third incineration, one third landfill. E.S = Swiss Eco-Factors 2013 according to the Ecological Scarcity Method (Ecoscarcity), published by Federal Office for the Environment (FOEN) which is an office of the Federal Department of Environment, Transport, Energy and Communications (DETEC). EF= Normalisation and Weighting based on the technical report by the Joint Research Centre (JRC), the European Commission’s science and knowledge service.

“It was interesting to see that the USE phase is the most relevant influence in the LCA. XLPE cable insulation enables lower electric losses in the cable and an increased energy efficiency in electric networks using vs PP in insulated MV cables. The recycling assessment for XLPE and PP lead to comparable net-benefits, which means that both cable insulation materials are 100 % qualified for recycling and therefore for circularity. Nevertheless the relevance of recycling should not be overestimated, as the respective net-benefits reduce the total environmental impacts along the full life cycle by only 1 %.”

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Borealis EverMinds™

Launched in 2018, EverMinds™ is an umbrella brand uniting the wide range of Borealis activities and initiatives aimed at making plastics more circular. As a dedicated platform, EverMinds promotes a circular mind-set among all Borealis stakeholders. The platform encompasses proprietary Borealis technologies as well as established brands such as Purpolen™ and Dipolen™. It facilitates deeper collaboration between Borealis and its partners in order to develop innovative and sustainable polyolefins solutions based on the circular model of recycling, re-use and design for circularity. EverMinds also extends to pioneering corporate programmes such as Project STOP, and engagement in industry initiatives like the the Polyolefins Circular Economy Platform (PCEP), and our project “Circular Economy for Flexible Packaging”.