Elsevier

Journal of Cleaner Production

Volume 229, 20 August 2019, Pages 680-694
Journal of Cleaner Production

Cost-benefit analysis of a circular economy project: a study on a recycling system for end-of-life tyres

https://doi.org/10.1016/j.jclepro.2019.03.223Get rights and content

Highlights

  • A crucial technological add-on to existing installations is illustrated.

  • The aim is to transform ELT textile fibre into a useful secondary raw material for different applications.

  • ELT fibre’s reuse presents a reduced environmental impact in comparison to the fibre’s incineration.

  • The high economic profitability makes this recycling system economically sustainable.

Abstract

End-of-life vehicles (ELV) represent a relevant waste source in Europe, even if ELV recycling is a priority of the European Union waste legislation and Environment Action Programmes (EAPs). End-of-Life Tires (ELTs) constitute a relevant portion of ELV waste. Textile fibre, which is a relevant portion of the ELT material, is considered as a special waste (European Waste Catalogue – EWC code 19.12.08). The main problem related to textile fibre is its contamination with rubber which does not allow to obtain a pure product economically and qualitatively useable.

The aim of this paper is to illustrate an innovative technology for ELT fibre's recycling, which allows to transform textile fibre into a useful secondary raw material for different applications.

In particular, the use of ELT fibre as additive for bituminous conglomerates has been investigated. The different processes have been analysed from an environmental point of view, applying the Life Cycle Assessment methodology. It came up there is an impact reduction in case the ELT fibre is reused as additive for bituminous conglomerates, instead of disposing it (through incineration).

Moreover, the financial and economic sustainability of the related technological process has been evaluated to check whether the process is sustainable in the long term. Starting from the results of the Life Cycle Assessment, economic performance indicators have been calculated, by applying the European Commission methodology for cost-benefit analysis. According to the present cost-benefit analysis, in the medium and long term the system is financially viable, and the high economic profitability makes the process economically sustainable. Furthermore, a sensitivity analysis as well as a risk assessment have been carried out in order to identify critical variables, evaluate risks and define risk mitigation measures. According to the sensitivity analysis performed, the project is not highly risky since even in the worst scenario the possible loss is moderate.

Based on the results of this analysis, it can be concluded that this ELT fibre's recycling system can be replicated across Europe, conveniently fostered by national policies (such as subsidies, value added tax etc.).

Introduction

Nowadays, end-of-life vehicles (ELVs) constitute a massive waste source in Europe, even if ELV recycling is a priority of Union waste legislation, as underlined in the ELV European Directive, 2000/53/EC (European Commission, 2000).

End-of-life tyres (ELTs) constitute a major portion of the ELV waste: every year, about 3.4 million tonnes of old tyres are disposed of in Europe, most being dumped or sent to landfill, in direct contravention of the EU rules banning landfilling of both whole and shredded tyres (EASME, 2015; ETRMA, 2015; European Directive, 2000).

The Italian law defines the legal framework and assigns the responsibility to the producers (tyre manufacturers and importers) to organise the management chain of ELTs (DM, 2011; DM, 2012). The crucial steps are collection, sorting, transformation and recovery in authorized treatment companies. The treatment and the recovery process of ELTs is primarily aimed at recovering triturated rubber in various sizes and types, which represents the main portion of the ELT material (Ramarad et al., 2015; Schnubel, 2014; WBCSD, 2010). During the treatment of tyres, two other sub-products are generated in significant quantities, namely steel and textile fibre (Pacheco-Torgal et al., 2012; Ecopneus, 2013).

Regarding the textile fibre's recycling, the main problem is the presence of rubber within the ELT fibre (40–60%), which makes it impossible to obtain a pure product economically and qualitatively useable. The cleaning practice is not commonly adopted due to the absence of a market that justifies the required efforts and resources. The main consequence is that both ELT treatment companies and end-users are discouraged to invest in fibre's recycling; thus, the dirty fibre goes to landfill or to waste incineration plants and cement production furnaces (ETRMA, 2015; Ecopneus, 2013).

Besides these problems, the use of fibre as recovery material presents mechanical and technological limitations. After the process, the textile fibre takes the form of “soft bundles”, which poses numerous problems such as: 1) the fibre bundle materials cannot be mixed and dispersed uniformly within any material (such as plastic compounds or bitumen conglomerates); 2) due to the accumulation of electrostatic charge within the bundles, an electrostatic effect is generated (called “bridge effect”), which, together with the fibre morphology, tends to obstruct the loading and extruding phases; 3) the low specific weight of fibre bundles (140 kg/m3) makes their transportation too expensive, hence strongly limiting the possibility of selling them in the market. For these reasons, as mentioned, ELTs are usually disposed.

The present paper focuses on the use of the ELT fibre as reinforcement in asphalt. The value of roads and infrastructures realized with the reinforced asphalt mix is expected to be higher due to a longer lifetime (a lifetime of 40–50 years is expected, while the lifetime of “normal” asphalts is 6–7 years) (Gonzalez et al., 2012; Liang et al., 2015). Moreover, the new conglomerates can be used in different climatic conditions ensuring wider market opportunities as well as replication across the EU. Furthermore, due to its mechanical properties, the new asphalt will consistently reduce the public procurement costs related to the rehabilitation and maintenance of roads and infrastructures (Blessen et al., 2016).

Besides presenting this new technological process, the aim of this paper is to assess its environmental and economic sustainability, by conducting a Life Cycle Assessment (LCA) analysis as well as a cost-benefit analysis (CBA).

This research draws primarily on the European Commission's “Guide to Cost-Benefit Analysis of Investment Projects” and on the European Investment Bank's “Economic Appraisal of Investment Projects at the (EIB)”. The former illustrates principles and rules to apply the CBA approach in different sectors, while the latter presents the economic appraisal methods that the EIB adopts in order to assess the economic viability of projects.

The present paper is organized as follows: Section 2 illustrates the project background, the cost-benefit methodology and Life Cycle Assessment methodology. In Section 3 results of the two analyses are presented, while in section 4 the financial sustainability and the economic performance of the process are discussed, together with the results of the risk assessment. Lastly, in Section 5 conclusions and recommendations are drawn.

Section snippets

Background of case study

Three phases compose the usual ELT disposal process. The first phase is the production of ground particles accompanied by the removal of the metallic fraction. For this phase, a double shaft grinder (which includes single knife elements), as well as electricity, water and oil are employed. The second phase consists in grinding the ground particles to reduce their dimensions. The equipment used in this phase is a fixed external cylinder (equipped with blades) which contains a rotating cylinder

LCA: life cycle interpretation

In Fig. 5 and Table A1, the average contribution of both scenarios for each impact category is reported. At first sight, neither scenario presents a clear environmental benefit.

Solely specific impact categories have been considered in this analysis, as some categories have not gained a world-wide recognition in the scientific community, differently from “toxicity” category (Renou et al., 2008). Other categories related to terrestrial transformation and terrestrial occupation have not been taken

Financial sustainability

Financial sustainability is a key feasibility condition for any typology of project. More specifically, “a project is financially sustainable when the risk of running out of cash in the future, both during the investment and the operational stages, is expected to be nil” (European Commission, 2014). To assess the financial sustainability, inflows are measured against outflows.

In the present analysis, in the first year the net cash flow is negative, due to relevant disbursements occurred in this

Conclusions

End-of-life tyres are one of the main source of waste in ELV sector. One aspect of fundamental importance for ELT recycling and valorisation of recovered materials is the proper implementation of European legislation regulated at the Italian national level by the DM Environment April 11, 2011, n. 82. The European Directive, 2000/53/EC is aimed primarily at preventing the production of waste resulting from vehicles, including tyres (classified as CER160103), and to encourage the reuse, recycling

Acknowledgements

This study is part of the activities carried out in the context of the “REFIBRE” Project (LIFE14 ENV/IT/000160) funded by the European Union within the Life Framework Programme. Special thanks are expressed to Steca S.p.A, Tires S.p.A and Toto Costruzioni S.p.A for the precious contribution.

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