Incentives for recycling and incineration in LCA: Polymers in Product Environmental Footprints

For material recycling to occur, waste material from a product life cycle must be made available for recycling and then used in the production of a new product. When recycling is beneficial for the environment, the LCA results should give incentives to collection for recycling and also to the use of recycled material in new products. However, most established methods for modelling recycling in LCA risk giving little or even wrong incentives. Many methods, such as the Circular Footprint Formula (CFF) in a Product Environmental Footprint (PEF), assign some of the environmental benefits of recycling to the product that uses recycled materials. This means that the incentive to send used products for recycling will be lower. If energy recovery also provides an environmental benefit, because the energy recovered substitutes energy supplied with a greater environmental impact, the LCA results may indicate that the waste should instead be sent to incineration – even when recycling is the environmentally preferable option for the society. This study aims to increase the knowledge on the extent to which PEF results, and LCA results in general, risk giving incorrect incentives for energy recovery from plastic waste. Our calculations focus on the climate impact of the recycling and incineration of LDPE waste generated in Sweden. Since this is a pilot study, we use easily available input data only. We estimate the net climate benefit through simple substitution, where recycled material is assumed to replace virgin material and where energy recovered from LDPE waste is assumed to replace average Swedish district heat and electricity. We then apply the CFF to find whether a PEF would give the same indications. Our results show no risk of a PEF or LCA giving incorrect climate incentives for incineration of fossil LDPE. However, an LCA can wrongly indicate that renewable LDPE should be incinerated rather than recycled. Our results indicate this can happen in a PEF when the heat and electricity substituted by incineration has 40-200% more climate impact than the Swedish average district heat and electricity.Our study also aims to increase knowledge about the extent to which correct incentives can be obtained through a more thorough analysis of incineration with energy recovery – specifically, through:\ua0\ua0\ua0 1. a deeper understanding of Factor B, which in the CFF can be used to assign part of the burdens and benefits of energy recovery to the energy instead of the product investigated, but which in the PEF guidelines by default is set to 0, or\ua0\ua0\ua0 2. a broader systems perspective that accounts for the effects of energy recovery on waste imports and thus waste management in other countries.We estimate Factor B based on the observation that waste incineration can be described as a process with multiple jointly determining functions. Waste treatment and energy recovery both contribute to driving investments in incineration. This, in turn, defines the volume of waste incinerated, the quantity of energy recovered, and the quantity of energy substituted. We propose that expected revenues from gate fees and energy are an appropriate basis for calculating Factor B. Up-to-date estimates of the expected revenues in the relevant region should ideally be used for the calculations. Lacking such data,we suggest the value B=0.6 can be used in the CFF when modelling waste incineration in Sweden. Our PEF calculations with Factor B=0.6 indicate such a PEF will identify the environmentally best option for plastic waste management in almost all cases. However, this is at least in part luck: Factor B will vary over time and between locations, and other parts of the CFF varies between materials.To account for the broader systems perspective, we develop two scenarios based on different assumptions on whether change in Swedish waste imports affects the incineration or landfilling in other European countries. The scenarios bring a large uncertainty into the results. This uncertainty is real in the sense that it is difficult to know how a change in Swedish waste imports in the end will affect waste management in other countries. The uncertainty still makes it difficult to draw conclusions on whether renewable LDPE should be recycled or incinerated.Our suggestions for Factor B and European scenarios both make the CFF more balanced and consistent: it now recognizes that not only recycling but alsoenergy recovery depends on more than the flow of waste from the life cycle investigated. However, neither Factor B nor the broader systems perspective amends the fact that LCA tends to focus on one product at a time. This might not be enough to guide a development that requires coordinated or concerted actions between actors in different life cycles – such as increased recycling or energy recovery. Assessing decisions in one product life cycle at a time might in this context be compared to independently assessing the action of clapping one hand. This will most probably not result in an applaud.Besides a more thorough assessment of energy recovery, we also discuss the option to give correct incentives for recycling from LCA by assigning the full environmental benefit of recycling to the product that generates waste for recycling but also to the product where the recycled material is used. We find that this 100/100 approach can give negative LCA results for products produced from recycled material and recycled to a high degree after recycling, because the benefits of recycling are counted twice. The LCA results would indicate that you save material resources by producing and recycling such products without ever using them. The 100/100 approach also lacks additivity, does not model foreseeable consequences, and does not assign a well-defined environmental value to the recovered secondary material.To guide concerted actions, like recycling or energy recovery, it seems systems analysis should ideally assess the necessary actions in combination. Many situations require the environmental impacts to be estimated for a specific product or a specific action. In some cases, however, the LCA results can be calculated and presented with, for example, the following introduction:“When the material is sent to recycling, you will, together with the recycler and the actor using the recycled material, jointly achieve this net environmental benefit: …”Such joint assessment of supply and demand for secondary materials means the allocation problem is avoided. It is also consistent with the recommendation in the old SETAC “Code of Practice” to assess life cycles with recycling by studying the inputs and outputs from the total linked system

Modelling incineration for more accurate comparisons to recycling in PEF and LCA

When recycling is beneficial for the environment, results from a life cycle assessment (LCA) should give incentives to collection for recycling and also to the use of recycled material in new products. Many approaches for modeling recycling in LCA assign part of the environmental benefits of recycling to the product where the recycled material is used. For example, the Circular Footprint Formula in the framework for Product Environmental Footprints (PEF) assigns less than 45% of the benefits of recycling to a polymer product sent to recycling. Our calculations indicate that this creates an incorrect climate incentive for incineration of renewable LDPE, when the recovered energy substitutes energy sources with 100–300% more climate impact than the Swedish average district heat and electricity. The risk of incorrect incentives can be reduced through allocating part of the net benefits of energy recovery to the life cycle where the energy is used; we propose this part can be 60% for Sweden, but probably less in countries without a district-heating network. Alternatively, the LCA can include the alternative treatment of waste that is displaced at the incinerator by waste from the investigated product. These solutions both make the LCA more balanced and consistent. The allocation factor 0.6 at incineration almost eliminates the risk of incorrect incentives in a PEF of renewable polymers. However, the focus of LCA on one product at a time might still make it insufficient to guide recycling, which requires concerted actions between actors in different life cycles

Choice of system boundaries in life cycle assessment

System boundaries in life cycle assessments (LCA) must be specified in several dimensions: boundaries between the technological system and nature, delimitations of the geographical area and time horizon considered, boundaries between production and production of capital goods and boundaries between the life cycle of the product studied and related life cycles of other products. Principles for choice of system boundaries are discussed, especially concerning the last dimension. Three methods for defining the contents of the analysed system in this respect are described: process tree, technological whole system and socio-economic whole system. The methods are described in the application's multi-output processes and cascade recycling, and examples are discussed. It is concluded that system boundaries must be relevant in relation to the purpose of an LCA, that processes outside the process tree in many cases have more influence on the result than details within the process tree, and that the different methods need to be further compared in practice and evaluated with respect to both relevance, feasibility and uncertainty

Evaluating the greenhouse gas impact from biomass gasification systems in industrial clusters – methodology and examples

Biomass gasification is identified as one of the key technologies for producing biofuels for the transport sector and can also produce many other types of products. Biomass gasification systems are large-scale industrial systems and it is important to evaluate such systems from economic, environmental and synergetic perspectives before implementation. The objective of this study is to define a methodology for evaluating the greenhouse gas (GHG) impact of different biomass gasification systems and to exemplify the methodology. The ultimate purpose of the methodology is to evaluate the GHG performance of different biomass gasification systems integrated in industrial clusters. A life cycle perspective is applied. Most biomass gasification systems are multiproduct systems, simultaneously producing biofuels, heat at different temperatures and pressures and electricity. The value, in economic terms and in terms of GHG emissions, is well defined for some products (e.g. biofuels), whereas for other products (such as heat and electricity) it is more uncertain and in some cases dependent on time and location

Harvsådd i konventionella och plöjningsfria bearbetningssystem

I en serie med långliggande försök jämfördes två storruteled (plöjning till 25 cm djup respektive stubbearbetning till 13 cm djup) och två småruteled (konventionell såbäddsberedning och sådd respektive harv sådd) för att testa om en reducering av antalet överfarter minskar de negativa effekter av packning av centrala matjorden som förknippas med plöjningsfri odling. Skörden bestämdes varje år på alla platserna. En undersökning av jordens fysikaliska och kemiska egenskaper samt rotfördelning genomfördes 1991 på en av de fyra försöksplatserna. - Bearbetningsdjup, aggregatstorleksfördelning och vattenhalt i såbädden och i såbäddens botten var liknande i de olika leden medan såbäddens botten var jämnare i det oplöjda ledet. Det påverkade ej grödans uppkomst, som var liknande mellan leden. - Andelen porer > 100 µm, porkontinuitet, mättad vattengenomsläpplighet och luftgenomsläpplighet påverkades positivt av plöjningsfri odling jämfört med konventionell bearbetning. - Skrymdensitet, packningsgrad och penetrometermotstånd var liknande i bearbetningssystemen i nivån 0-13 cm, men signifikant högre i oplöjda led i nivån 13-25 cm, där rotdensiteten var signifikant lägre. - Kalium och kol var koncentrerade till de övre 13 cm i oplöjda rutor, medan fosfor och pH ej påverkades av bearbetningssystemen. - Harvsådd gav 2 % högre skörd än konventionell såbäddsberedning och verkar vara ett gott alternativ till konventionell såbäddsberedning, men andra metoder för att reducera packningen av jorden, som till exempel däck med extremt låga tryck, bör testas

Effects of reduced tillage and liming on microbial activity and soil properties in a weakly-structured soil

Abstract The effects of reduced tillage and lime on crop yield and soil physical and microbial properties were studied in a weakly-structured silty clay loam soil. Two autumn primary tillage practices were compared, mouldboard ploughing to 20-25 cm and cultivation to 12 cm. Seedbed preparation was carried out by several harrowing operations in the mouldboard ploughed treatment, and with a PTO-driven harrow in the same operation as sowing in the shallow cultivation treatment. The tillage treatments were applied alone or were combined with liming aimed at soil structural improvement. Lime was added as 6.5 Mg CaO ha −1 before the start of the experiment and mixed into the top 12 cm of soil with a disc cultivator. A 4-year crop rotation was used: spring barley, spring oilseed rape, spring/winter wheat and oats, and all crops were compared each year. Crop residues were retained in the experiment and incorporated at cultivation. Aggregate stability was improved by the shallower tillage depth, probably as an effect of an increase in soil organic matter and a more active microbial biomass. Liming had little effect on soil structure variables but increased microbial activity to some extent. This was reflected in higher crop yields, especially when the shallow tillage depth was combined with liming. Penetration resistance in the seedbed subsoil was highest when mouldboard ploughing was carried out in plots without liming. Data were examined with principal component analyses, and the structures in the data were presented as scores and loading plots, which revealed groupings between samples and relationships between variables, respectively

RED, PEF, and EPD: Conflicting rules for determining the carbon footprint of biofuels give unclear signals to fuel producers and customers

Biofuel producers and other commodity suppliers are increasingly affected by conflicting rules for life cycle assessment (LCA). They may get multiple requests for LCAs to be used in various contexts, which require the application of different methodological approaches that vary in scope, system boundaries, data demand, and more. This results in increased cost and competence requirements for producers, as well as confusion among other actors including their customers. Differences in methodologies might also lead to various outcomes, conclusions and conflicting guidance regarding which fuels to prioritize or develop. We have analyzed the actual differences when applying three different frameworks: the EU Renewable Energy Directive (RED), the EU framework for Product Environmental Footprints (PEF), and the framework of Environmental Product Declarations (EPD), which have different modeling requirements. We analyzed the methods from a conceptual point of view and also applied the methods to estimate the carbon footprint on a wide range of biofuel production pathways: (i) ethanol from corn, (ii) fatty acid methyl ester (FAME) from rapeseed oil, (iii) biogas from food waste, (iv) hydrogenated vegetable oil (HVO) from rapeseed oil, and (v) HVO from used cooking oil. Results obtained for a specific fuel could differ substantially depending on the framework applied and the assumptions and interpretations made when applying the different frameworks. Particularly, the results are very sensitive to the modeling of waste management when biofuel is produced from waste. Our results indicate a much higher climate impact for, e.g., biogas and HVO produced from used cooking oil when assessed with the PEF framework compared to the other frameworks. This is because PEF assigns at least part of the production of primary materials and energy to the use of recycled material and recovered energy. Developing Category Rules for biofuels for PEF and EPD ought to help clarifying remaining ambiguities