SUbstance flow analysis of the recycling of small waste electrical ...

4. Data inventory 63
4. Data inventory
In this chapter, the origin of the data and the assumptions used to quantify the flows of
sWEEE in the different subsystems and the concentration of gold and palladium in sWEEE
are described.
4.1. Quantification of the flows related to sWEEE
4.1.1. Generation
Three methods were selected to carry out estimates of the WEEE generation: ‘simple delay’,
‘distribution delay’ and ‘batch leaching’ (see chapter 2.4.1). Data on historic sales volumes,
penetration rates in households and businesses, average lifetimes and average weights of
the different equipment types were needed to estimate the WEEE generation with these
methods. Some previous studies, like EEA (2002), US EPA (2007a; 2008) and Huisman et
al. (2007) published estimates of the generation of WEEE. Because the underlying
assumptions and the geographical boundaries of their estimates differ from the ones used in
this thesis, the results from these studies could not be used.
4.1.1.1. Sources of data
To estimate the WEEE generation, data reporting the sales volumes over at least the past 20
years are required, due to the long lifetimes of some equipment types. Some public
institutions like the German Federal Statistical Office Destatis, the US Census Bureau and
the statistical office of the European Union Eurostat make some sales data publicly available.
However, sales data are primarily provided by private market research institutes like Gartner,
IDC, the Consumer Electronics Association, Inform or the European Information Technology
Observatory (EITO). The data is usually a part of market studies designed for the
manufacturing industry. Financial units (for example revenues from sales in million dollars)
are often used, so that some conversions are needed for a material flow analysis, where
mass units are required. If the data is available in financial units, additional information or
assumptions on the average sales price of a device are necessary to convert the financial
flows into flows in units of devices. These flows can then be converted into mass flows by
multiplying by the average weight of the devices. Since both the average price and the
average weight differ depending on the equipment type, each equipment type has to be
considered separately.
The high price of the private market studies did not allow a direct access to the full studies,
but the historic sales data are partially published in other studies. For example, US EPA
(2008) makes data available on sales of televisions, mobile phones and computer-related