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

2. Background and definitions 35
2.4.1.2. Lifetime of EEE
The lifetime of EEE is an important parameter that influences the generation of WEEE. As
reported by Babbitt et al. (2009), three kinds of time periods possibly called “lifetimes” in the
literature can be distinguished:
1. First use time: Time from sale to the end of the use by the first user
2. Total use time: Time from sale to the end of the use by the last user, including
reuse(s)
3. Total lifetime: Use, reuse(s) and storage of unused devices (time from sale to
collection as waste)
Matthews et al. (1997) described these three periods and quantified the fractions of personal
computers that are reused and stored after first use (Figure 4).
Purchased PC
First Use
Generation
of WEEE
Storage
Reuse
5 years
10% 45%
45%
45%
22.5%
50%
3 years
22.5%
3 years
Figure 4
Lifetime of PC from purchase of EEE to generation of WEEE, including first use, reuse
and storage (Matthews et al. 1997, designed by EEA 2002)
According to Scheidt (2007), ICT products are often stored by the householder for 3 to 5
years before they are discarded. Nokia (2008) and Murakami et al. (2009) also reported the
tendency of the users to temporarily store unused WEEE before recycling. US EPA (2007a)
estimated that in 2005, approximately 460 million devices were put into storage and/or reuse
in the USA. Three-quarters of all of the computers sold in the USA remain in a garage, closet
or storage space (NSC 1999). Murakami et al. (2009) calls these stocks of unused EEE
‘hibernating stocks’. To approximate the WEEE generation, which begins when the user
discards an EEE, the ‘total lifetime’ including reuse and storage is needed. The average total