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A Life Cycle Assessment methodology is applied to the manufacturing of shoping trolleys, as well as the impact of their abandonment through the use of collection vans and subsequent refurbishment operations.
Tackling the issue of shopping trolley abandonment addresses circular economy principles, in that valuable resources are maintained and used as long as possible. This paper seeks to evaluate the environmental impact of collecting and processing abandoned trolleys and subsequently returning them into use. The number of abandoned trolleys is not insignificant. In 2017, 520 000 trolleys were reported as abandoned in the UK [1]
This study presented in this paper used a methodology standardised by the International Standardisation Organisation (ISO), known as Life Cycle Assessment (LCA) to analyse the potential environmental impact of collecting and handling abandoned shopping trolleys within a specific area of the City of Coventry, UK. The study aims to quantify the environmental impact of trolley abandonment, providing inputs to policymakers, shop owners as well as guidance to the general public.
The Cannon Park Shopping Centre and surrounding suburban area within the City of Coventry, UK, was chosen as a case study. The shopping centre contains a "superstore” supermarket serving the local populace, as well as the local student population of the neighbouring Warwick University.
Retail establishments such as Cannon Park make use of specialist trolley collection services. These services, henceforth referred to as “commercial collection services” or CCS, offer a downloadable app, which the public can use to notify the CCS drivers of abandoned trolleys. The drivers collect the reported trolleys and return them to the retail establishments, or for refurbishment, if required.
The local university Estates department also collects abandoned trolleys around campus, stores it in a central holding pen and notifies the CCS for collection. Approximately 20 trolleys are collected and stored in the central holding pen each week by Estates, with a weekly mass collection from the holding pen by the CCS. The Warwick University Estates department uses a diesel Transit Tipper 350 RWD 2.0 TDCi with a tail lift to collect trolleys. The diesel van collects abandoned trolleys as parts of its daily movements around campus. The CCS also use a similar vehicle, confirmed by a personal communication.
The CCS also offer trolley refurbishment services. At the refurbishment process depot, the trolleys are stripped of components (wheels, handlebars, etc.) and steelwork is repaired (weld repair). The trolleys are put through a pyrolysis process to remove existing zinc coating and lacquer. Finally the trolleys are electro-plated with zinc and have a lacquer applied to protect the zinc coating.
The considered life cycle is shown in Figure 1 below. The number of trolleys collected in each of the driving scenarios is shown in Figure 2.
Figure 1. Life Cycle stages of shopping trolley study.
Figure 2. Number of trolleys collected per week for each driving scenario, centered on the originating supermarket “Tesco".
The goal of the presented study is to evaluate the environmental impact of collecting and processing abandoned shopping trolleys around the Canley and Warwick University area of Coventry, UK through a hot spot analysis.
The study consisted of the following life cycle stages:
The function of a shopping trolley is to transport products around a store and to the customers vehicle. The reference flow (which is the amount of product required to meet the function) is one shopping trolley.
The Life Cycle Inventory (LCI) consists of an inventory of all relevant flows in the system boundary. Use was made of the GaBi life cycle inventory, which contains data on energy production, use and distribution. Other data includes raw material extraction and transport. The GaBi software provides supporting documentation to its database sets and references to the source of the data. Data which was not available through the GaBi database was collected from literature sources.
The LCI model was divided into the three stages shown in Figure 3 below.
Figure 3. LCI model of trolley manufacture, collection and refurbishment.
The Life Cycle Impact Assessment (LCIA) was informed by previous transport-related LCA studies [2][3]. The ReCiPe Midpoint method[4] was selected due to covering midpoint indicators. A midpoint method evaluates environmental impacts earlier along the cause-effect chain than endpoint methods. Endpoints methods are generally considered to have a higher statistical uncertainty than midpoint methods[5]. The hierarchist perspective for the characterisation model was selected, using a 100-year time horizon for climate change and falls between the Individualist (20-year time horizon) and Egalitarian (1000-year time horizon).
The impact categories selected for this investigation includes the well-known Climate Change (characterised as Global Warming Potential (GWP)), used in transport related studies[3]. Fossil Depletion (FD) and Metal Depletion (MD) captures the impact of extracting minerals and fossil fuels. Fine Particulate Matter Formation (FPMF) captures the impact of air pollutants through vehicle use and is used in transport related studies[6]. Photochemical Ozone Formation (POF) assesses the impact of photochemical ozone pollution through vehicle use.
The impact of water pollution was accounted for through Freshwater Eutrophication (FE) and Marine Eutrophication (ME).
Table 1 shows the sum of environmental impacts for each life cycle stage (manufacturing stage, collection stage and finally the transport and refurbishment stage). All data have been normalised to the manufacturing phase for each environmental impact. It is clear that the manufacturing phase dominates by orders of magnitude across all environmental impacts. The “transport and refurbishment” phase is consistently the second largest impact life cycle phase. The collection stage consistently shows the least impact across all categories.
Overall, the manufacturing phase showed the highest impact across all life cycle stages, with the steel wire basket contributing the largest amount to manufacturing environmental impact. The relative magnitude of the impact of steel may be attributed to mining and processing being included in the model.
The collection phase showed the least impact compared to manufacturing and “transport and refurbishment” phases. A modelling approximation was necessary to use a diesel passenger vehicle instead of a van; however the appropriate fuel and vehicle mass were incorporated into the model. Given that the overall use phase results were two to five orders of magnitude less than the manufacturing phase, a clear ranking of magnitude of impact for the use phase can be established.
The “transport and refurbishment” phase was the second highest contributor to environmental impacts of the three life cycle stages, with hot dip galvanisation being the main contributor across all environmental impacts.
Table 1. Environmental impact of the 3 life cycle phases.
Manufacturing stage (normalized) |
Collection stage (normalized) |
Transport and refurbishment stage (normalized) |
|
Climate Change |
1.0E+00 |
1.1E-02 |
8.4E-02 |
Photochemical Ozone Formation, ecosystem |
1.0E+00 |
3.7E-03 |
9.9E-02 |
Fine Particulate Matter Formation |
1.0E+00 |
2.0E-03 |
8.0E-02 |
Metal depletion |
1.0E+00 |
3.5E-05 |
1.6E-01 |
Fossil depletion |
1.0E+00 |
1.2E-02 |
8.6E-02 |
Freshwater Eutrophication |
1.0E+00 |
2.2E-03 |
5.7E-02 |
Marine Eutrophication |
1.0E+00 |
8.2E-04 |
3.3E-02 |
A case study of the environmental impact of collecting abandoned trolleys in the Canley suburban area of Coventry city was presented. While focused on a specific suburban area, the results are easily transferable to other similar cities within and outside the UK.
The LCA results have shown that the environmental impacts of manufacturing shopping trolleys dominate all other life cycle stages. It may be concluded that any environmental impact caused by collecting and refurbishing abandoned trolleys are minimal compared to the impact of losing the trolleys through abandonment, which may result in new trolleys being manufactured to replace them.