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Issue 06/2018

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From Science & Research

From Science & Research How to calculate land use accurately A sensitivity approach By: Christian Schulz, Research associate Hans-Josef Endres, Head of the institute Hochschule Hannover, IfBB – Institute for Bioplastics and Biocomposites Hannover, Germany Satisfying (growing) human needs requires efficient use of limited economic resources. This also applies to the discussion about the use of available agricultural land, which in particular bioplastics has increasingly had to face in recent years. Previous estimates by IfBB - Institute for Bioplastics and Biocomposites, Hannover, Germany, have already shown that the impact of producing new generation bioplastics (New Economy such as PLA, Bio-PE, etc.) based on agricultural raw materials, such as starch, sugar and vegetable oil, is currently marginal at around 0.05 % in 2017 and probably 0.07 % in 2022 in terms of land use compared to the global amount of arable land. Figure 1 shows the development of the global production capacity of the New Economy bioplastics industry, which currently stands at around 2.3 million tonnes per year. In comparison, the amounts of Old Economy bioplastics, such as natural rubber (e.g. for tires), cellulosics (esp. for non-degradable cigarette filters and textiles) and linoleum with a total of 17 million tonnes per year are much larger. Comparing previous land area estimates for both industries, it can be seen that the production capacity of the Old Economy is only 7 to 8 times higher than that of the New Economy, but the supply of raw materials for the Old Economy with a total of 15 million hectares needs more than 20 times the land area compared to the New Economy. (Old Economy is not subject of the considerations, as these bioplastics have been used for more than 100 years and in addition go into applications that are very different from those of the New Economy). Despite these differences in size – both being easily marginalized when comparing to the land use of pastures for grazing of livestock at 3.5 billion hectares (FAO 2018) –, plastics from the New Economy yet had to face up to the question of land use. As previous assumptions to calculate land use for biobased plastics in the New Economy have always been estimates made with high safety factors and using a conservative approach, the following considerations should indicate which factors are relevant for land use estimation, how these can be made more realistic and how it affects the already marginal share of global arable land. In order to find sensitivities and to compare variations in results for land use of bioplastics, one needs to know how it basically was calculated before. This approach has been used as standard method for European Bioplastics’ annual statistic update until 2017 and is adapted in this year with more specific data of bioplastics producers, missing until now in the estimates. Based on process data from literature, experts and own calculations, Figure 2 shows a sample process route showing the manufacturing steps involved from the raw material to the finished product, specifying the individual process steps, intermediate products, and input-output streams. PLA is used here as an example, as it is one of the most important New Economy bioplastics. This is only one representative of all other New Economy bioplastics, to which this approach is applied – each with its own process route. Production capacities and land use Old and New Economy bioplastics Figure 1 New Economy bioplastics global production capacities 12 000 000 Natural rubber 56 000 Linoleum 3 5 000 4 000 4 305 1 740 672 000 New Economy bioplastics 1 2 900 000 Cellulose 2 10 978 000 Natural rubber 140 000 Linoleum 3 in 1 000 t 3 000 2 000 1 000 0 2 028 1 697 737 663 1 034 1 291 2014 2015 2 048 757 1 291 2016 2 274 881 1 393 2017 Forecast 2 565 2022 2 273 000 New Economy bioplastics 1 5 800 000 Cellulose 2 1 PLA, PHA, PTT, PBAT, Starch blends, Drop-Ins (Bio-PE, Bio-PET, Bio-PA) and other 2 Material use excl. paper industry 3 Calculations include linseed oil only Bio-based/non-biodegradable Biodegradable Total capacity Biopolymers, facts and statistics 2018 – 41 42 bioplastics MAGAZINE [06/18] Vol. 13

From Science & Research To obtain land use data from production capacities in this bottom-up approach (see Table 1), it needs producer-specific production capacities of a type of bioplastics to be multiplied by the output data of the corresponding process routes. If producerspecific feedstock was known, it was taken into consideration. In other cases, where these data were missing, only the most common used crop per material was taken into consideration (e.g. corn starch for PLA). For the basic assumptions referring to PLA, previous estimates of IfBB resulted in a need of 0.37 hectares land for feedstock cultivation per tonne of material. This is a corn-based, PLAspecific global average land use factor, for which the following calculation impact factors (CIF) are assumed. One obvious impact factor on land use of bioplastics might be the production capacity itself. According to own research, total annual installed capacity for PLA worldwide in 2017 was roughly 240,000 tonnes, which gives 88,300 hectares according to the basic assumptions. However, is relying on the installed capacity correct? Very few industrial plants run at full degree of capacity continuously, so an optimistic sensitivity would be 85 % degree of capacity. Another impact factor is the region specific yield of a feedstock in different countries. While for the basic estimation for PLA made out of corn, a global average yield of 6.5 tonnes of corn per hectare over the past decade (weighted by production amount) (FAO 2018), corn being grown in the United States in the same period would yield in 9.5 tonnes per hectare and the same acreage in China delivered 40 % less of corn (5.5 t / ha). This is even more important, as corn from USA makes up to 37 % of world’s corn production, but China, with its significantly lower yield per hectare still ranks at an important one fifth (20 %) of global corn production. Therefore it has a decreasing effect on the global average corn yield (6.5 t / ha). Further impacts derive from natural harvesting fluctuation. Using single year data leads to tremendous deviation in calculating PLA land use. Comparing available corn yields between 2002 and 2013 for e.g. corn in the USA shows, that there is a deviation between minimum and maximum of 3.2 tonnes per hectare (Average yield: 9.1 t / ha). By using either minimum or maximum yield data of a given period for calculation will result in this case in a fluctuation of land use of +43 % or -30 %. But even when looking at a global average yield for corn, the choice of a certain decade leads to different results. Using a global average yield over a mid-term period (10 years) helps to minimize natural harvesting fluctuation while at the same time provides data, which are not influenced by single local yield deviations. When comparing two different time periods (2002 – 2011 and 2003 – 2014), the worldwide general increase in harvesting yields of corn raised by 2.5 %. For other (food) crops relevant in bioplastics production, the increase is at the same level or even higher, e.g. sugar beet (+ 5.9 %), sugar cane (+ 1.9 %) and castor oil (+ 17.1 %). Advances in crop growing techniques and better feedstock yields result in a lower land use, which decreases to the same extent for each bioplastic material. Even without changes in bioplastics technology (1st, 2nd, 3rd generation), future land use per tonne of bioplastic material will de facto decrease. Additional impact factors could arise from the source of feedstock (e.g. PLA made from sugar cane versus corn starch) and allocation assumptions. Allocation is in detail also a very complex topic and would go beyond the scope of this comparison as there are different factors itself, which can be used. In general, this would be mass-balanced, energy-balanced or economicbalanced allocation. In this case, if using residues is being taken into account, the bioplastic material will only be burdened with parts of the full impact of its land use. To make a proposal, the results will cover 30 % use of residues. Stepping back from the different impact factors and having a look at the resulting effects on land use of PLA Figure 3 shows the impact for the recent global capacity of about 240,000 tonnes for PLA. If all raw material was from one country (USA), depending on different yields per year, this amount of PLA land use ranges from nearly 80,000 up to almost 115,000 hectares. And even using a global average yield can still cause slight variations, depending on which time horizon is assumed (± 2,600 hectares). Last comparison in Figure 3 shows the influence of locally produced feedstock as displayed here for Chinese and US-American corn, resulting in a difference of nearly 43,000 hectares. Figure 4 compares further impact factors concerning a more realistic degree of plant capacity being used or an overall Yield [ t PLA/ha] 6 4 2 0 Figure 3 Figure 4 2.7 Land use for PLA derived from corn Comparing effects of different feedstock impact factors 240,000 t PLA (2017) 2.1 3.0 114,500 ha 88,300 ha 80,000 ha Base calculation Local harvest fluctuation (USA) 2.7 2.8 88,300 ha Time horizon Global average 2.3 3.9 104,300 ha USA vs. China Global / regional higher is better 85,700 ha 61,500 ha Base Low High Yield [ t PLA/ha] 8 6 4 2 0 Land use for PLA derived from corn Comparing effects of various impact factors 2.7 2.7 Base calculation Prod. capacity 85 % 240,000 t PLA (2017) 88,300 ha 75,000 ha 61,500 ha 38,100 ha 3.9 Allocation overall 30 % 6.3 Source of feedstock higher is better Base Variations bioplastics MAGAZINE [06/18] Vol. 13 43

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