Life cycle energy and CO₂ emissions analysis of food packaging: an insight into the methodology from an Italian perspective

Abstract

Packaging is strictly connected to environmental issues as it is a product characterised by high material consumption rate; it is often transported over long distances and has a short life. Providing environmental analysis is, therefore, urgent to identify energy and resources efficient solutions. The paper, taking advantage of a real case study, presents a life cycle-based comparative analysis among three different food packaging systems. The paper compares the life cycle of tin steel, polypropylene and glass-based packaging of an Italian preserves producer. The analysis leads to the conclusion that, for the baseline scenario, polypropylene packaging represents the greenest solution, whereas glass packaging is the worst choice. The paper presents a scenario analysis varying both the method used for accounting for recycling as well as the recycling rates of the packaging materials. Changes in overall results with parameters analysis changing are calculated and highlighted throughout the paper. The impact of a reuse policy of the glass-based solution is also analysed; a model for disposable glass packaging is proposed and the obtained results are compared with the single use polypropylene and tin steel-based packaging. In order to analyse the impact of different End of Life scenarios on the present case study, collecting as well as recycling rates of some European countries have been used. The results revealed a significant fluctuation both in energy consumption and in CO₂ emission as the nation changes. Summing up, a methodology for packaging environmental impact analysis is applied to a real case study, some crucial aspects of the methodology have been analysed in depth in order to give a contribution in packaging environmental impact analysis.

Keywords:

• Industrial packaging
• life-cycle engineering
• sustainable packaging solutions

1. Introduction

Packaging is a straightforward example of a product with high material consumption. Making materials has a significant environmental impact: Ashby (2013) states that making materials consumes about the 21% of the global energy demand, and causes the 20% of the global CO₂ emissions. Approximately 40% of the municipal solid waste in Western Europe can be ascribed to packaging materials, along with at least 33% of all solid waste in the United States. As income levels increase and lifestyles change, packaging waste is likely to increase in developing countries as well (Worrell 2014). Moreover, the packaging is characterised by a brief life cycle significantly contributing to the overall material consumption; Shen and Worrell (2014), for instance, state that in the EU-15 member states, packaging accounts for the highest share accounting for 38% of the whole plastic consumption followed by building and construction sectors. Several materials are involved in packaging, Worrell (2014) reports a breakdown analysis showing that in EU for 2010, the 5 main packaging materials: wood, paper, plastics glass and the metal, accounted respectively for 15, 40, 19, 20 and 6% of the total packaging waste.

A large variety of policy instruments have been introduced in many countries to manage packaging waste, in fact in EU-27 countries, the recovery rates for packaging waste increased from 66.8% up to 78.5% over a 7 year period time (from 2005 to 2012) (Eurostat 2015a). Packaging has a strategic role in global environmental impact: besides the material consumption-related impact, the packaging affects also the impact of the transport sector (which account for 23% of the World CO₂ emissions (IEA 2014)). As a matter of fact, nowadays, because of globalisation products, and their packaging, are often transported over large distances causing CO₂ emissions. Developing Life cycle Assessment (LCA)-based analysis is, in consequence, mandatory to provide useful and reliable guidelines concerning the environmental impact of packaging.

Actually, when reliable environmental analyses of products have to be developed, LCA is a widely accepted approach to evaluate the environmental impact of a product by considering all its life cycle stages.

The present paper aims at offering a contribution to environmental analysis of packaging. The paper presents the results of a real case study and reports a comparative analysis among three different packaging systems providing in-depth analysis on different aspects of the methodology itself. In order to analyse the impact of End of Life (EoL) strategies, the paper presents a scenario analysis with both varying the used method for accounting for recycling as well as the recycling rates of the packaging materials. The present analysis includes the environmental impact caused by jar filling and sealing; such aspect, neglected by the scientific literature, was developed by developing experimental electrical energy measurements. Summing up, the paper, going through a thoroughly life cycle-based analysis of the three most used packaging systems (glass, metal and plastic), aims at offering a wide perspective on environmental analysis of packaging systems.

As packaging is strictly connected to environmental issues, over the past years several researchers have paid attention to this aspect and some comparative packaging LCA have been published. Dhaliwal et al. (2014) compare the environmental impact of two packaging options for contrast media: a polymer bottle and a traditional glass bottle. The authors state that using polymers rather than glass bottles allows to lower the environmental impact of contrast media packaging.

Albrecht et al. (2013) compare from environmental, economic as well as social impact point of view the most common European fruit and vegetable transport packaging: single-use wooden and cardboard boxes and re-useable plastic crates. Papong et al. (2014) deal with the bio polymer-based packaging, as a matter of fact they compare from an environmental perspective biopolymer (such as PLA) with fossil-based polymers such as polyethylene terephthalate (PET) as packaging solution for drinking water bottles. The authors states that PLA has better performance in most of the impact categories they consider. Barlow and Morgan (2013) present a review on polymer packaging for food and analyse potential environmental impact reduction strategies. They highlighted the importance of the amount of used material, in fact they state: that ‘moving towards packaging which is more recyclable should not be the highest priority. The results show that minimization of the material used whilst retaining mechanical and barrier properties is the best way to achieve a reduction in environmental impact’. The paper also discusses the advantages arising from the use of biodegradable polymers, the authors highlight that the benefits are currently the subject of debate.

Shen, Worrell, and Patel 2010 present the environmental impact of PET bottle-to-fibre recycling by means of LCA methods; several PET recycling approaches are considered and some general guidelines for environmental impact reduction are provided within the paper.

Toniolo et al. (2013) investigate the market segment of food packaging characterised by the employment of post-consumer PET bottles; the aim of this study was to compare the environmental performance of an innovative recyclable package with an alternative package that is not recyclable (both of the options are produced from recycling postconsumer PET bottles).

Kang et al. (2013), conduct a study to compare the environmental effect of weight reduction and of different material composition of packages for bacon packaging. Zampori and Dotelli (2014) focus on the LCA of two packaging alternatives of a poultry product, in particular, a polystyrene-based tray and an aluminium bowl were considered. The authors present a full life cycle analysis and underline the relevance of cooking step and how a specific design of the tray can allow significant lowering of the overall emissions. The authors also analyse the impact of the selected method for accounting for recycling on the final results. Detzel and Mönckert (2009) compare two different scenarios for the environmental performance of a refillable glass bottle and of an aluminium can for beer distribution, the author state that the overall result is strongly affect by the transport distance.

Accorsi, Versari, and Manzini (2015) propose a LCA approach to compare two different packaging solutions for extra-virgin olive oil. In this research, the authors propose a comparative environmental analysis of a glass bottle vs. a plastic one. The findings from the LCA revealed the potential of PET alternative in reducing the environmental impact.

Simon, Ben Amor, and Foldenyi (2016) develop a comparative LCA and analyse 11 different drink packaging solutions made out of five different materials. The authors point out that several variables affect the result and it is difficult identifying the overall best and the worst packaging material. The authors state that ‘only special case studies can support the decision-making to design an environmentally sound beverage packaging system’.

Bertoluci, Leroy, and Olsson (2014) propose LCAs of packaging design with varying both the household waste collection rates and the technologies for waste treatment (recycling and incineration). As a matter of fact, the authors analyse the waste treatment policy adopted by some European countries (corresponding to the national situation of five European countries: France, Germany, Italy, Spain, Sweden) and analyse the impact of such policy on the environmental performances of three different olive packaging solutions: daypacks, glass jars and steel cans. Wikström et al. (2014) analyse the environmental impact of six different packaging systems; the authors analyse the connection between packaging design and food waste underlining the food losses relevance in terms of environmental impact.

Besides the comparative analysis among packaging systems made of different materials, another interesting comparative approach, characterising the packaging environmental impact analysis, concerns the comparison between disposable and reusable solutions. Reuse of packaging allows to avoid the environmental burden of material and manufacturing steps of a life cycle, such an aspect might make the reusing strategy the best solution in terms of environmental impact for packaging. Both academic and industrial world started to analyse the benefits deriving from reusing. Aparecido et al. (2013) compare a disposable and returnable for an engine head packaging system, the paper particularly pay attention to the role of the reverse logistics, the authors found out that the returnable packaging results in economical as well as environmental gains. Mata and Costa (2001) compare the environmental impacts of the returnable and the non-returnable glass beer bottles, this study was performed for several reuse percentages and returnable bottle cycles. The research demonstrates that the relative importance of the impacts related to the use of returnable and/or non-returnable bottles depends on the number of cycles performed by the returnable bottles. Ashby (2013) reports two case studies concerning environmental impact of reuse namely: reusable grocery bag and reusable polycarbonate glass water.

Accorsi et al. (2014) compare a reusable system to traditional single-use packaging to quantify the economic returns and environmental impacts of the reusable plastic container in the field of food packaging. They apply a LCA analysis considering CO₂eq as environmental indicator. The authors underline that such kind of studies are case study dependent and that reusable packaging options deserve further attention.

Simon, Ben Amor, and Foldenyi (2016) compare reusable and disposable beverage packaging systems and identify a breakeven point (number of reuse to be developed to make the reusable packaging environmentally preferable). The breakeven point was reached after just one refill by the PET-bottle, glass needed two refills instead.

WRAP (2010), by presenting a review of several comparative LCA studies, provides general guidelines for properly dealing with reusable packaging LCA analyses.

As shown, the scientific literature concerning environmental impact of packaging is wide and diversified as these kind of studies are affected by the analysed case study. The present paper reports energy and CO₂ emissions life cycle results of a food packaging Italian case study. Specifically, following the aforementioned research trends, both comparative analyses among packaging systems made of different materials as well as comparisons between disposable and reusable solutions are developed. The analysed case study allowed to deal with several aspects concerning the environmental impact of packaging such us: material ecological properties, package weight, suitability for reuse. The research aims at contributing to create a base of knowledge in terms of energy and resources efficiency in the packaging sector.

2. Case study description and major assumptions

The case study is based on the production activity of a preserves production firm located in Palermo. The firm produces mainly typical Sicilian food and sells its products both in Italy and in some European countries. Among the several products the firm produce, in this study, the life cycle of caponata packaging is analysed. Caponata is a typical Sicilian food made mainly of aubergines, olives, onions, celery, tomato and olives oil. To be more specific, the packaging size able to contain 200 g of product is taken to account. Three different packaging alternatives are analysed: two traditional (widely used within the analysed sector) and an innovative one (still to be implemented by the firm). As far as the traditional ones are concerned, both Tin-steel and glass are taken into account, as for the innovative alternative a polypropylene-based one is considered. The three packaging alternatives are reported in the Figure 1; from now on in the paper, the three alternatives will be referred to as: TS = Tin Steel can; GL = Glass; PP = Polypropylene.

Figure 1. The analysed packaging options: (a) tin steel can (TS), (b) glass (GL); (c) polypropylene.

It is worth pointing out that the packaging suitable for containing caponata have to meet both economic and technical requirements. As a matter of fact, caponata is characterised by a pH value lower than 4.4, hence a pasteurisation process instead of sterilisation can be used to guarantee the proper food safety. The selected materials meet the requirements to bear the thermal cycle characterising caponata pasteurisation. Of course, the selected materials satisfy also the requirements for containing, protecting, storing and transporting the food.

2.1. Goal and scope

The aim of the present study is to characterise the life cycle primary energy and CO₂ emissions of three different food packaging systems. Namely, three different packaging options made out of three materials are considered: Tin Steel, Glass and Polypropylene. Moreover, the potential saving obtainable using a reusable glass packaging is analysed. An analysis with varying EoL strategy is also proposed.

2.2. Functional unit

Concerning the functional unit, the environmental impact arising from the life cycle of a packaging system containing a 200 g portion of food is considered. This choice was driven by the will to make the procedure, as well as the obtained results, more general as they don’t directly depend on the production volume of a given year. In fact, information related to the firm’s production volume refers to the year 2013. The amount of secondary packaging required by each packaging system was calculated and the environmental impact of cardboard ascribable to the functional unit was included in the analysis.

2.3. System boundaries

A comparative approach strategy was selected to better spot the strengths and the weaknesses of each option. Energy, resources and emissions have been monitored throughout the packaging life cycle. Actually, a cradle to grave approach (in most cases, the recycling was selected as EoL strategy) was followed. In Section 4, the assumptions and the details of the inventory step for each production stage are specified. The environmental impact of material production, product manufacturing, product use and product disposal were fully analysed. Also the transportation was analysed since such products are often exported and, therefore, the impact related to transportation could play a relevant role. Specifically, the impact related to packaging transportation from the manufacturing plant to food cooking firm (Contorno Ltd.) was considered, the transportation of products up to the points of sale was also included in the analysis. In fact, the outbound logistics impact was included in the analysis by an allocation procedure.

Environmental impact related to sealing and pasteurisation stages were considered. Namely, the electric energy for these two production stages was experimentally measured for the three packaging solutions.

Figure 2 shows the sketch of the selected system boundaries for developing the analysis, the main considered factors are also highlighted.

Figure 2. The system boundaries.

2.4. Selected indicators

To properly compare the packaging alternatives, two indicators were considered: Primary energy and CO₂ emissions. According to Ashby (2013), they can be monitored and collected in a straightforward and reasonable way. Even though CO₂ emissions represent the actual environmental sustainability indicator, the assessment of primary energy consumption is also useful because of the direct connection to economic concerns.

When electric energy was experimentally measured, it was converted into primary energy considering an average efficiency of the electric production equal to 35% to account for generation and transmission losses. When necessary, for converting the electric energy into CO₂ emissions CO₂/KWh coefficient characterising the Italian energy mix (IEA 2014) was considered.

3. Life cycle inventory

3.1. Material and EoL

As regards, the accounting for the environmental impact of the material stage, the first necessary input data is the bill of materials for each analysed packaging option. The amount of involved material for primary packaging as well as for secondary packaging is reported in the table 1. In order to take into account, the impact related to material production, the table reports embodied energy as well as the CO₂ footprint for the primary production of each material involved in the analysis. Recycling has been mainly considered in the present research as selected EoL strategy. Actually, the credit deriving from recycling are calculated and included in the analysis.

Table 1. Inventory data for material and End of Life steps.

Packaging ID	Bill of materials	Weight (KG)	Embodied energy. Primary production (MJ/kg)	CO2 footprint. Primary production (kg/kg)	Embodied energy. Recycling (MJ/kg)	CO2 footprint. Recycling (kg/kg)	r (%)	R (%)
TS	Tin steel including top and bottom caps	0.064	36.95	1.98	16.5	0.98	76	44
	Cardboard	0.009	51.50	1.15	19.5	0.76	85	40
GL	Glass	0.145	10	0.75	802	0.49	70	26
	Tin steel (top cap)	0.008	36.95	1.98	16.5	0.98	76	44
	Cardboard	0.010	51.5	1.15	19.5	0.76	85	40
PP	Polypropylene	0.019	79	3.85	20	2.1	37	6
	Polyamide film	0.001	122.5	7.95	42.5	2.55	37	5
	Cardboard	0.009	51.5	1.15	19.5	0.76	85	40

It is worth pointing out that there is no single universally acceptable criterion to account for recycling. Nevertheless, some useful guidelines are provided by Hammond and Jones (2010). Overall, it is worth pointing out that the directives strongly suggest to avoid double counting. In the present paper, the principal methods to deal with environmental credits arising from recycling are considered: (1) the recycling content approach and (2) the substitution method. The first one ascribes the full benefits of material recycling to the start of its life, neglecting the benefits arising from the end-of-life recyclability. Vice versa, the second one allocates the environmental credit of recycling to the end-of-life stage. Equations 1 and 2 represent the embodied energy calculation per kg of material for the recycling content approach and for the substitution method, respectively:(1) (2)

where

R = recycled content (fraction of recycled material in the input material)

r = recyclability (fraction of material recycled at the end-of-life);

E_R = embodied energy, secondary production;

E_V = embodied energy, primary production.

E_d = energy for disposal of waste material.

It is worth pointing out that the CO₂ emissions can be computed accordingly. In order to properly account for material recycling benefits, reliable values of both R and r have to be identified. As for the input recycled content (R) of the involved materials, the values as reported by Ashby (2013) were used. As far as the recyclability (r) is concerned, the recycling-rated values available on Eurostat (2015b) were used. As a matter of fact the recyclability depends on recovery and sorting system characterising each country. Eurostat provides very detailed statistics about the packaging waste stream in all the European countries. The ones characterising Italy were used, such values are reported in Table 1.

Table 1 reports also energies and CO₂ emissions for both primary and secondary (recycled) material production, the reported values were found on the materials databases provided by Ashby (2013) and Hammond and Jones (2010).

Analysing the difference between the recovery rate and the recycling rate for polypropylene, it is possible to assume that about 30% of the plastic packaging waste are processed by combustion for heat recovering.

This EoL strategy allows to recover a certain amount of material embodied energy although an extra penalty in terms of CO₂ emissions arising from the waste combustion has to be considered. In this paper, the difference in terms of CO₂ emissions between the emissions caused by material combustion and by the national electrical grid for producing the same amount of electricity was considered. Summing up, in the present research, besides the recycling, the energy recovering from combustion is also considered when accounting for benefits deriving from EoL strategies.

The comparative analysis is first developed applying the substitution method; a digression on the influence the used method for accounting for recycling is instead presented in section. 5.1

3.2. Transport

Life cycle analyses of food and beverage packaging have to properly take into account the impact of transport. Actually, the food is often transported all over the world and the means of transportation cover long distances.

Often, two or three transportation means are involved for a single delivery. In this paper, taking advantage of a real case study, it was possible to thoroughly account for both inbound and outbound logistics.

Overall, the energy consumed and the CO₂ emissions emitted during shipment was considered. Concerning the inbound logistics, the shipment of the empty packaging system from the manufacturing firm was considered.

Table 2 reports, for each packaging solution, the necessary transport inventory input data.

Table 2. Inventory data for accounting for transport impact of the inbound logistic.

Packaging ID	Component	Transport distance (km)	Mean of transportation	Energy consumption factor (MJ/kg Ton)	CO2 emission factor (kg/kg Ton)
TS	Tin-steel can	675	14 tonnes truck	1.5	0.11
GL	Glass jar	1873	Coastal shipping	0.27	0.019
	Tin steel (top cap)	668	Coastal shipping	0.27	0.019
PP	Jar + top cap	1271	14 tonnes truck(580 km)/ Coastal shipping(691 km)	1.5/0.27	0.11/0.019

The environmental impact related to inbound logistics of the functional unit is, therefore, straightforwardly obtained for each packaging solution. Unlike inbound logistics, outbound logistics require an allocation procedure. In fact, the sales network is wide: clients of the considered company are spread out across Sicily, Italy and also some European countries. In consequence, depending on the final destination, each packaging can be characterised by very different delivery distances (distance between the Contorno Ltd. and the points of sale) and different means of transport (Truck or Ship).

Analysing the sales of the company, it is possible to notice that the company delivers its products to 45 different final destinations: 29 of them are Sicilian, 13 spread across Italy and 3 located in Europe. For the sake of secrecy, no further details can be provided about the sales of the Contorno Ltd.

Such diversity must be somehow reflected in the considered functional unit, which must represent the whole outbound transport scenario. To deal with this aspect, the overall environmental impact due to the outbound transportation ascribed to the single functional unit was calculated as reported in the Equation (3)

(3)

where

i = ith point of sales/destination

n = number of different point of sales

C_Etr = energy consumption factor for 14 tonnes truck diesel;

C_Esh = energy consumption factor for ship;

d_itr = distance covered by truck for destination i;

d_ish = distance covered by ship for destination i;

q_i = numbers of boxes delivered to destinations i;

q_tot = numbers of boxes sold in the reference year;

M_FU = mass of the functional unit for given packaging option.

It is worth pointing out that CO₂ emissions related to transport can be calculated accordingly using the related coefficient reported in Table 2.

3.3. Manufacturing

The main manufacturing steps regarding jar and can manufacturing were included; in particular, this life cycle phase accounts for the environmental impact related to transform the raw material into the final desired shape. In Table 3, the considered processes, as well as the corresponding energy intensity and CO₂ emissions, are reported. Of course, the reported values have to be multiplied by the masses reported in the Table 1. It is worth pointing out that also the manufacturing steps of the secondary packaging material (cardboard) were included in the analysis. All the eco-properties of the manufacturing step have been found in Ashby (2013); for the resistance welding the emissions due to the electric energy have been calculated considering the Italian electric grid footprint.

Table 3. Inventory data for manufacturing step.

Packaging ID	Bill of materials	Manufacturing process	Energy	CO2 emissions
TS	Tin steel	Forming	4.5 (MJ/kg)	0.34 (MJ/kg)
		Resistance welding	2 (MJ/m)	0.175 (kg/MJ)
GL	Glass	Glass moulding	8.7 (MJ/kg)	0.69 (kg/kg)
	Tin steel (top cap)	Forming	4.5 (MJ/kg)	0.34 (kg/kg)
PP	Polypropylene	Polymer moulding process	21.5 (MJ/kg)	1.6 (kg/kg)
	Polyamides	Polymer extrusion process	22 (MJ/kg)	1.625 (kg/kg)
TS/GL/PP	Cardboard	Cardboard production process	0.5 (MJ/kg)	0.026 (kg/kg)

3.4. Use

As far as the use phase is concerned, the environmental impact that can be ascribed directly to the packaging features has to be identified in the sealing and pasteurisation stages. Even though these steps don’t represent the classic consumer use impact, the authors decided to include this impact in the use phase to better differentiate this stage form the packaging manufacturing step.

The sealing and pasteurisation stages are the final manufacturing steps of the production line of the food cooking and packaging procedure set up by the Contorno Ltd.

The sealing as well as the pasteurisation steps differ with packaging material changing. Using different packaging materials results in different machine as well as different production times. The electric energy consumption therefore absorbed by these operations changes together with the related CO₂ emissions. To calculate the electric energy consumed by these two production stages time as well as the absorbed power of the involved machines were monitored and collected for three different packaging solutions.

The material of the packaging strongly affects the pasteurisation thermal cycle; as a matter of fact such production step depends on the material thermal property and particularly on its thermal conductivity. In this step, the temperature of the food contained has to reach an assigned value and such temperature has to be kept constant for a given time span. The pasteurisation times have been optimised for the three packaging solutions and they are equal to 50, 35 and 15 min respectively for glass, tin-steel and polypropylene packaging. Since it is a continuous production process which starts with ingredient cutting and finishes with the pasteurisation step, the observation time span related to the entire production batch processed by the firm (1200 kg of food corresponding to 6000 FU) was considered. Finally, the environmental impact of each functional unit was obtained, the primary energy as well as the CO₂ emissions for each packaging solution is reported in Table 4.

Table 4. Energy and CO₂ emissions during the use phase for single functional unit.

Packaging solution	Primary energy (MJ)	CO2(kg)
TS	0.028	0.003
GL	0.035	0.003
PP	0.028	0.003

It is possible to observe that the TS and PP measurements have the same values; such a result is due to the fact that the pasteurisation time reduction is neutralised by the energy consumed by the sealing machine; in fact, the polypropylene sealing machine absorbs higher power level when compared to the sealing machine of the traditional packaging.

4. Life cycle inventory results

To present the comparative results, a baseline scenario characterised by a substitution approach method implementation (Equation (2)) was considered. Figure 3(a) and (b) reports primary energy and CO₂ emissions life cycle inventory results. The Energy consumption as well as the CO₂ emissions for each life step and for each packaging solution are detailed. Under the item material, it is reported the impact of the material without considering the credit deriving from EoL step (recycling/incineration), which is, in turn, separately reported. Overall, it is possible to notice that the polypropylene packaging is the greenest solution for both the indicators. On the contrary, the glass packaging is always the worst choice. This is mainly due to the higher weight characterising the glass packaging; such an aspect, in fact, badly affects the environmental impact of all the three mains life cycle stages (material, manufacturing and transport). It is worth pointing out that the glass manufacturing step has a very bad impact in terms of CO₂ emissions; this aspect further worsens the overall performance of the glass packaging environmental impact when compared with the other solutions with respect the CO₂ emissions indicator.

Figure 3. Life cycle inventory analysis results: (a) primary energy consumption, (b) CO₂ emissions.

To better understand the significance of each life cycle stage on the whole life cycle, the CO₂ emissions shares are reported in Table 5. It is possible to notice that material manufacturing steps have a significant impact across the three analysed alternatives. The material phase is the dominant phase for the tin steel can and for the polypropylene solution, whereas for the glass-based packaging, the manufacturing step is the dominant phase exceeding the material one by about 1%. It is worth pointing out that, for the analysed case study, the transport phase is still a relevant one accounting for up to 18% for the Tin Steel packaging.

Table 5. CO₂ emission shares for the three packaging solutions.

TS	GL	PP

5. Scenario analyses

In order to offer a wider perspective on the applied methodology, in-depth analyses on some aspects have been developed. Concerning the methodology, the influence of the used method for accounting for recycling is analysed and the results are reported in Section 5.1. Moreover, two different scenario analyses are presented: one concerning the reuse policy (Section 5.2) and another varying the material recycling rates (Section 5.3) as they vary across European nations.

5.1. Analysis with methodology for accounting for recycling credit changing

Analysing the results form Section 4, it is possible to state that the material production impact, under its effective contribution (i.e. including the credit from recycling), plays a relevant role within the life cycle impact of a packaging system. As a consequence, aside from recycling performance characterising each material, the applied methodology to account for recycling could strongly affect the analysis and the overall results. As described in Section 3.1, there is not a single recognised method but mainly two approaches: the recycled content which considers the fraction of recycled material at the start of its life (R) and the substitution approach which, instead, considers the recyclability (r = fraction of material recycled at the End-of-Life). In order to analyse the impact of the methodology on the analysed case study, both the approaches were implemented (by applying Equations (1) and (2)); R and r values as reported in Table 1 were used. Results, in terms of primary energy and CO₂ emissions, are reported in Figure 4(a) and (b).

Figure 4. Life cycle inventory results with varying the method for accounting for recycling benefits: (a) primary energy consumption, (b) CO₂ emissions.

It is possible to notice that the recycling content approach and the substitution method lead to substantially different results; nevertheless, the mutual result between the considered packaging is not affected. In particular, it is possible to state that the substitution method gives better results for all the three packaging solutions and for both the considered indicators. This result can be explained by realising that the recycled contents (R) for each material are always lower than the r values.

Since it has been demonstrated that the selected method does not affect the overall analysis, from now on, the substitution analysis is considered as method. This choice was driven by the fact the packaging life style is quite short and, although the substitution approach neglects the credit form recycling related to the input material, the end life phase (and its related benefits) is close enough to consider such an assumption acceptable (Hammond and Jones 2010.)

5.2. Glass packaging reuse

It is worth underlining that the global performance of a product strongly depends on the EoL strategy.

Reuse is certainly one of the most promising option, as reusing allows the saving of energy and emissions and avoids primary and secondary material production as well as the product manufacturing step. Actually, reusable packaging systems are often typically heavier than single use packaging, but such a higher burden is shared among number of trips/reuses. The overall environmental impact associated with raw materials and energy used in manufacture is usually lower than the case of single-trip packaging.

Some studies (Aparecido et al. 2013; Ashby 2013; Mata and Costa 2001; WRAP 2010) demonstrated that reusing in the food/beverage sector is often the most environmentally friendly solution. It is clear that higher the number of jar is reused, the lower the environmental impact of each jar trip is. On the contrary, within each reuse, the reverse logistics environmental impact as well as the energy related to jar washing and sanitation has to be included. In order to quantify the environmental impact of a reusable packaging system, the Equation (4) is proposed:

(4)

where

i = number of reuses;

E_Ri = Energy consumed by a reusable jar for a single use/trip;

E_effmat = Effective Energy (considering the credit arising from recycling) related to material production;

E_man = Energy related to jar manufacturing step;

E_inlog = Energy consumed by the inbound logistics;

E_use = Energy consumed by the use phase;

E_outlog = Energy consumed by the outbound logistics;

E_revlog = Energy consumed by the reverse logistics.

The Equation (4) is made of a variable component, which depends on the number of reuses, and of a constant part which is the sum of three components: (E_use, E_outlog, E_revlog).

It is worth pointing out that the CO₂ emissions as well as the other impact categories can be calculated accordingly.

For the analysed case study, the only reusable packaging system in the present form is glass.

In order to analyse the impact of a potential glass jar reuse strategy implementation, an analysis with varying number of reuses is developed. In this analysis, the weight of the reusable and of the disposable glass jar has been considered unchanged. In consequence, all the energy components already quantified for the disposable glass jar can be used. As for the reverse logistics, the same distances and means of transportation of the outbound logistic have been considered. In fact, it was assumed that the jar, once collected after being used, has to cover the entire distance back up to the filling and sealing company. Of course, during the reverse logistics, the jar is empty and as a consequence, the related environmental impact is lower. It is worth pointing out that the energy for washing and sanitising the jar should be included to provide a full analysis. Nevertheless, the WRAP (2010) report states that such a contribution can be neglected and, considering the lack of available data, the washing/sanitation impact was not included in the present study. In Figure 5, the energy and CO₂ emissions of each single glass jar with varying the number of reuses are reported. In particular, the results for 1, 2, 5 and 10 reuses (named respectively GL1, GL2, GL5 and GL10 in Figure 5(a) and (b)) are shown along with the primary energy and CO₂ emissions for disposable Tin steel (TS) and Polypropylene (PP) solutions. As far as the energy consumption is regarded, it is possible to notice that reusing strongly lowers the consumption after only a single reuse, becoming the least energy intensive solutions. As expected, as the number of reuses increases the energy decreases becoming always closer to the constant amount of Equation (4) (E_use + E_outlog + E_revlog).

Figure 5. The impact of reuse policy for the glass packaging. (a) Energy, (b) CO₂ emissions.

Concerning the CO₂ emissions, the decreasing trend of the emissions with number of reuses increasing is still evident and relevant; nevertheless, two reuses are necessary for the glass to be the greenest solution, substantial gain is visible only after three reuses.

Reuse is one of the most promising EoL strategies to lower the overall environmental impact of packaging. This is because the energy intensive material and manufacturing steps are shared by the number of product cycles/reuses. Despite the positive aspects of reuse, it is worth pointing out that put in practice a full reuse strategy might be very challenging; and the following comment reported by Thomas Dyer (2014) clarifies this statement:

The shift toward globalization has meant that glass containers for food and drink are diverse in size and shape and often originate from remote locations, making container return uneconomical and impractical in terms of logistics. Thus, in many countries, recovery of intact glass bottles has seen a decline, magnifying the need for recycling.

For implementing a reuse strategy, many factors have to be taken into account and the environmental one is only one of them.

5.3. Analysis with varying the EoL strategies

The waste treatment policy varies across countries and in consequence, the life cycle environmental impact of product varies too. When environmental performances of products are evaluated and compared, all the potential EoL options have to be taken into account. In order to analyse the impact of different EoL scenarios on the present case study, the collecting as well as recycling rates related to some European countries have been used. In fact, the packaging life cycle environmental impact is strongly affected by the recycling rates of the material which it is made of. The recycling rates considered in the previous section concerns the Italian collecting and recycling policy. In order to give to the present research, a more general impact the waste management treatment (Collecting, recycling as well as incineration rates) of Germany, France, Belgium, UK and Greece have been considered (Eurostat 2015a, 2015b).

The main idea is to make the final evaluation somehow not depending on the recycling performances of one single country. In Table 6, collecting (C) as well as the recycling rates (r) are reported. It was assumed that the waste which are collected but not recycled (difference between the collection rate and the recycling one) are sent for incineration. Landfill was assumed as EoL solution for the remaining waste.

Table 6. Collecting rate (C), recycling rate (r), fraction of wastes to be incinerated (I) and fraction of material to be landfilled (L) for different European countries (Eurostat 2015a, 2015b).

	TS				Glass				PP				Card board
	C	r	I	L	C	r	I	L	C	r	I	L	C	r	I	L
Italy	74.3	73.6	–	26.4	70.9	70.9	–	29.1	71.8	37.5	34.3	28.2	91.9	84.5	7.4	8.1
Germany	93.3	92.3	–	7.7	84.7	84.7	–	15.3	99.7	49.5	50.2	0.3	99.8	87.6	12.2	0.2
France	74.7	73.9	–	26.1	73.5	73.5	–	26.5	64	25.1	38.9	36	96	91.8	4.2	4
Belgium	97.3	97.4	–	2.6	100	100	–	0	92.7	41.5	51.2	7.3	96.8	89.8	7	3.2
UK	52.1	52.1	–	47.9	67.8	67.8	–	32.2	25.2	25.2	0	74.8	86.5	86.5	0	13.5
Greece	38.2	38.2	–	61.8	54.7	54.7	–	45.3	32.2	32.2	0	67.8	83.6	83.6	0	16.4

As far as the incineration credit/debit is concerned, it is worth pointing out that while for the energy consumption indicator the incineration always results in a credit, as for CO₂ emissions it may result in a debit. As a matter of fact, burning material leads to a certain amount of energy recovery but causes unavoidable CO₂ emissions. In this paper, it is assumed that the energy created by incineration is used to produce electric energy; in consequence, the difference in terms of CO₂ emissions between the emissions caused by material combustion and by the national electrical grid for producing the same amount of electricity was considered.

As far as the carbon footprint (CO₂ emission per KWh), values of all the analysed countries were found in the database provided by IEA (2014). Figure 6 depicts the energy consumption (Figure 6(a)) and the CO₂ emissions (Figure 6(b)) of the whole life cycle for the three packaging solutions. It is possible to notice that within each packaging solution, the results widely vary as the considered nation varies. In the figure, the difference with respect to the baseline scenario (Italy) is reported. The highest fluctuations were obtained for the TS packaging where a difference as high as 16% is noticeable for the Greek scenario. Even though the difference in absolute terms varies noticeably across countries, the mutual result between the considered packaging is not affected and the polypropylene-based packaging remains the greenest one.

Figure 6. Life cycle results across European countries: (a) primary energy consumption, (b) CO₂ emissions.

Unlike the energy indicator, for the CO₂ even the overall results are affected. Actually, because of the debit due to polypropylene incineration, the polypropylene performances worsen and for three countries (Germany, France, Belgium), the tin steel packaging results the best solution. Such results underline once more the difficulty in generalising packaging life cycle results.

6. Conclusions

The present research presents a contribution to life cycle based environmental analysis of packaging. The research, taking advantage of an industrial case study data availability, presents a thoroughly life cycle inventory analysis. The case study concerns an Italian preserve production company and the paper moves through a comparative analysis of three different packaging solutions: tin steel, glass and polypropylene-based packaging. The paper takes into account all the steps of a whole life cycle of each packaging option.

The analysis of the baseline scenario results led to the conclusion that polypropylene packaging is the greenest solution. On the contrary, the glass packaging is always the worst choice.

The present research also deals with the analysis of the impact of both different methods and scenarios on the final results. In order to analyse the impact of EoL strategies, the paper presents a scenario analysis with varying both the used method for accounting for recycling as well as the recycling rates of the packaging materials.

Concerning the method for accounting for recycling two methods were applied and differences in energy and in CO₂ emissions were highlighted. Besides the methods, the impact of different EoL strategies was also analysed. The impact of a reuse policy of the glass-based solution was first analysed. A model for disposable glass packaging is proposed and the obtained results were compared with the single use polypropylene and tin steel-based packaging. Results show that reuse can lead to substantial saving and it is one of the most promising ways to go for reducing the packaging environmental impact; nevertheless, some weaknesses for a full reuse implementation have still to be overcome.

In order to make results more general, the waste treatment and policy of different European nations were taken into account. The methodology was applied with varying both collecting as well recycling rates as they vary across Europe. Results reveal a significant fluctuation both in energy consumption and in CO₂ emissions values as the nation changes. As for the CO₂ emissions, even the overall results were affected and the tin steel packaging resulted the best solution.

Summing up, throughout the paper, a methodology for packaging environmental impact is applied to a real case study, some crucial aspects of the approach have been analysed in-depth in order to contribute to create the base of knowledge in the domain of energy and resource efficiency of packaging systems.

Further developments in packaging environmental analysis should better explore the reuse option for all the analysed materials. Reuse might result in substantial environmental impact savings, several issues should be analysed though. Identifying, for each material, the proper reusable packaging architecture and the proper reverse logistics solutions are the first issues to deal with. Moreover, the packaging damaging rate should be considered and included in the analysis. Once reliable scenario is set up a comparison with a full recycling option could outline environmental guidelines for food packaging solutions.

Notes on contributors

Giuseppe Ingarao is an assistant professor. His research activity focuses on sustainability analysis and modelling of manufacturing processes.

Steven Licata is a master’s thesis student.

Marzia Sciortino, PhD, is in charge of developing innovative food packaging solutions at Flli. Contorno SRL.

Diego Planeta is an assistant professor. His research interest concerns science and food technology focusing both on processes and products.

Rosa Di Lorenzo is an associate professor. Her research activity focuses on sustainability and modelling of manufacturing processes.

Livan Fratini is Full Professor. His research activity focuses on innovative manufacturing processes analysis and engineering.

Disclosure statement

No potential conflict of interest was reported by the authors.