Effects on metal resource use from reusing laptops - A comparison of impact assessment methods

Conference poster, 2018

Proposed measures of the circular economy are assumed to be environmentally favourable but there is limited empirical evidence on how this actually works in practice or if it is true. A life cycle-based approach has been argued useful for critical assessment of circular economy measures. In life cycle assessment, several perceptions exist regarding what the environmental problem with metal resource use consists of, manifesting in differing impact assessment methods. Since these methods have been shown to give diverging results it is plausible that the choice of LCIA-method could have significant implications for the assessment of circular economy for products such as laptops. Except for recycling, there are no comparative assessment studies of circular economy measures that deploy complementary LCIA-methods on metal resource use.

A life cycle assessment was conducted studying reuse as mediated by a resale and refurbishment company, using several LCIA-methods in parallel. This served to find which metals that are important in laptops depending on LCIA-method and how metals may benefit from reuse. Second-hand laptops were deemed functionally equivalent to new ones. Reuse was assumed to double product lifetime of 70% of sourced laptops to six years in total. In EoL, recycled metals were assumed to displace respective primary production.

The LCA study shows that reuse of laptops contributed to resource-efficiency in two principal ways: firstly, through the intended use extension (41% reduction compared to new laptops) and secondly, by steering material flows, i.e. laptops that cannot be reused, into recycling. This increased recycling was found especially important according to some LCIA-methods (varying between 1-9% reduction compared to new laptops) which characterise metals that are functionally recycled as important (typically methods using average crustal concentrations as part of their characterisation factors) and negligible in others (typically using reserves as part of their characterisation factors). Some metals have visible contributions in all methods and are unlikely missed if only using one LCIA-method. Other metals are visibly contributing in one or a few methods and thereby risk getting missed in such cases. It is therefore advisable to use complementary methods to minimise risks of overlooking relevant metal resource use aspects when studying circular economy measures for electronics.