3. Bio Flow Monitor
3.1 Introduction
The starting point for the Bio Flow Monitor is the Material Flow Monitor (MFM) that is already used to derive CE relevant indicators for the ICER (Berkel, van and Delahaye, 2019; Hanemaaijer et al., 2021). The MFM, compiled by Statistics Netherlands, describes the physical material flows, measured in million kilos, to, from and within the Dutch economy. The MFM consists of a supply table and a use table. These tables distinguish around 350 goods (e.g. raw materials, semi- and final manufactures), natural resources (e.g. minerals, natural gas and wood) and residues (e.g. waste and CO2 emissions). They also cover around 130 economic sectors, households, imports, exports and the environment. As the MFM complies with internationally agreed statistical standards of the System of National Accounts (SNA) and the System of Environmental Economic Accounting (SEEA), it can compare physical flows with their economic counterparts like GDP and employment.
In the MFM, 100 percent bio-based products – like wheat and timber – are already distinguished. However, for products that may have either a biotic or abiotic base (e.g. plastic) and products that consist partly of biomass (e.g. furniture), the bio-based share cannot be determined. As explained in the methodological section below, by applying bio-based shares to the MFM and converting everything to dry matter, the Bio Flow Monitor (BFM) is compiled. This results in two supply and use tables: one with only biotic flows and one with only abiotic flows. These tables are used to derive CE relevant indicators related to the bio-based economy.
3.2 Methodology
Van Berkel and Delahaye (2019) describe in detail how the MFM is compiled . This section presents the methodology used to convert the MFM into the BFM (see also Berkel, van et al., 2022).
The first step is to convert the values of the MFM into dry weight (see Annex 7.5 for dry matter contents). In bio-based products in particular, water content may differ between products. Therefore adding up different kinds of biomass does not give a clear picture of the useable (i.e. not including water) amount of biomass available. This problem is solved by expressing biomass in terms of its dry matter content. This also solves the problem of changes in biomass weight as a result of changes in the water content during the production process. To convert the fresh matter values in the MFM, JRC provided conversion coefficients for agricultural products (Joint Research Centre, Gurría et al. (2017)). For products not covered by JRC we obtained data from 2.0 LCA (Merciai et al. (2013) (e.g. for abiotic products, paper and wood), and through the literature and expert guesses (e.g. for boats and furniture). A final option is apply known coefficients for products to similar products (e.g. apply wood coefficients for a door).
The second step is to convert the dry matter MFM by applying bio-based shares. Initially the same methodology is used as that used by NOVA (Piotrowski and Carus, 2017) and CE Delft (Lieshout et al., 2018). For each relevant Prodcom code NOVA estimated an EU-28 average share for 1) total production volume with any bio-based content, and 2) bio-based content of the share of bio-based production. These shares are sometimes presented as a range; for the sake of convenience we always took the average. By multiplying both NOVA shares with CBS production figures we estimated biotic and abiotic volumes for each relevant Prodcom code. For some Prodcom codes we needed to convert non-kilo physical units (e.g. pieces or m2) to kilos. To do this we linked a Eurostat conversion table for CN codes to Prodcom codes. Lastly, volumes of biotic and abiotic goods were aggregated to comply with the MFM classification, after which the bio-based share is estimated for each MFM code. In this initial stage bio-based shares for industrial production are estimated.
In the next stage bio-based shares for imports, exports and used goods are estimated. Import and export shares are estimated by linking the NOVA Prodcom shares to the international trade codes (CN). If one Prodcom code links to multiple CN codes, or vice versa the average share is taken. The method used to estimate biotic and abiotic production figures is also used for imports and exports. The bio-based shares for domestically used goods are estimated by combining bio-based production and import figures. In the end this resulted in bio-based shares for imports, production, use and exports of a wide range of MFM goods.
As not all bio-based products are covered by the NOVA Prodcom shares, bio-based shares were allocated to the remaining MFM codes based on expert guesses and the literature. Products from agriculture and the food industry were considered to be 100 percent bio-based, and for composite goods, for example musical instruments or household waste, a share was estimated. This ultimately resulted in bio-based shares for all MFM codes (see annex 7.5). A first estimate of the BFM was compiled by multiplying these shares by the figures in the MFM.
Due to differences and uncertainties in the applied shares, the BFM supply and use tables are no longer balanced. The final stage in completing the BFM is to reconcile the supply and use of goods and the input and output of sectors. This is done in two steps, first large discrepancies are reconciled manually. Subsequently, the remaining smaller differences are removed through modelling using a generalised least-square method that modifies the set of figures as little as possible while satisfying certain constraints (Bikker et al., 2012). The constraints make sure that a relation between two variables is fixed or remains within certain limits. For example, the supply of processed meat may not exceed the use of livestock by a slaughterhouse. In addition the results of the method are driven by reliability weights; these weights are devised to ensure that the figures deemed most reliable are modified least. For example, the supply side is considered to be more reliable than the use side because more source data are available.
3.3 Results
3.3.1 Biotic and abiotic supply and use tables
The results are two sets of supply and use tables (SUT) in million kilos of dry matter for 2018. The BFM is presented in annexes 7.1, 7.2, 7.3 and 7.4 as one set with biotic and another set with abiotic materials. In the tables goods, resources and residuals and economic sectors are aggregated to a large extent in order to eliminate confidential information and boost the plausibility of the data.
Even in the MFM, data at the highest level of detail are difficult to judge in terms of plausibility as underlying data are collected from sources of different quality, and often cannot be verified through alternative data sources. The additional assumptions (dry matter content and bio-based shares) applied to compile the BFM make it even harder to check the quality of the data. During the reconciliation process of the bio SUT some economic sectors (e.g. dairy, animal feed, textile, paper and plastic/rubber production) were difficult to reconcile. This is an indication that the quality of the data can be improved. Also, for some sectors the amount of packaging material used was large compared to production volumes. For the Abiotic SUTs the in- and output of the chemical sector was difficult to reconcile. Despite these concerns, the most detailed tables are available for analytical purposes from CBS on request (milieurekeningen@cbs.nl). The interpretation of the data in the SUTs and their usability to derive CE relevant bio-based indicators are discussed in chapter 4.