Questionnaire, definitions, allocation of inputs and outputs to different paper products produced in the same mill.
The questionnaires are available through the two Associations as a supplement to this report. A list of definitions is included as well. The questionnaires were slightly modified to improve data collection in some areas, most particularly in relation to transport of raw materials (wood and recovered paper) to the mills and transport of containerboard from the mills to the corrugated board plants. Some improvements were also made with regards to data collected relating to water consumption at the mills and starch consumption at the corrugated plants. The questionnaires for paper mills included a mass balance for recovered paper mills, energy balance, water balance and carbon balance.
The questionnaires treat the paper mills and corrugated board plants as a black box, asking for annual inputs to and outputs from the mill or plant.
Differentiation between the processes within the site, such as power generation, pulping, paper production, wastewater treatment, has not been made.
According to ISO 14044, allocation of the impacts of primary fibre production (the cradle) and waste treatment (the grave) of wood fibre to the phases in between the cradle and the grave of the life cycle should be avoided, wherever possible. In our case this is done by expanding the product system and considering the expanded system with a closed-loop approach.
In cases where the mill produces other products (e.g. sold energy), the mill reports only the inputs and outputs that were allocated to paper production. No allocation was made to by-products, so the reported inputs and outputs include the production of these by-products.
For those paper mills producing more than one grade of paper and/or market pulp it is necessary to allocate inputs and outputs to the different paper grades or pulp. Mill staff who filled in the questionnaire have done the allocation according to causality.
For a mill producing both Semichemical Fluting and Kraftliner the total input of wood to the mill site has been reported as well as a percentage allocation figure indicating how much of the total wood consumption should be allocated to Semichemical Fluting and how much to Kraftliner.
Details on allocation are described in the following paragraphs of this chapter.
Checking of the data and the allocation percentages
The collected annual data were processed to determine inputs to and outputs from the paper mills for the production of one tonne net saleable paper for each paper product, using allocation percentages in case more than one product was produced at one mill.
The following calculation was made in most cases:
|annual in(out)put x allocation %|
|tonnes nsp2 produced in 2017|
Some mills have reported waterborne emissions in g/m3 waste water and for those mills the following calculation was made:
|g/m3 waterborne in(out)put x allocation % x m3 water|
|tonnes nsp2 produced in 2017|
To increase the quality of the database the results were checked as described below.
The data per tonne nsp2 for each paper product were compared by technical experts from the participating mills to investigate if variation of the data could be explained by differences in the applied technology. Data that could not be explained were rechecked to make sure that data from the individual mills were correct.
Mills were also asked to recheck the data in case any of the balances was questionable.
For the corrugated board plants, due to a large dataset of primary data was available it was possible to scrutinise the data statistically for any outlying data points for each inventory item. Where outliers were identified these were either investigated further with the data suppliers or where this was not possible or no satisfactory explanation could be ascertained, such outliers have been excluded from the analysis.