Presentation at 12th Society and Materials Conference (SAM) 2018 in Metz
While reducing the demand for fossil fuels the energy transition requires new technologies, e.g. battery storage systems, many of which come with an increasing demand for critical materials such as cobalt and lithium. The criticality of a material is caused by supply and/or environmental risks associated with its provision. Thus, in order to counteract the occurrence of new resource risks, measures are needed to reduce resource criticality of key technologies for future energy supply. The circular economy (CE) is often proposed as a means to reduce the environmental impact of raw materials and to create new opportunities for value creation. This poses the question to what extent CE approaches such as recycling and reuse can actually lead to a reduction of resource criticality of future energy technologies and whether there are trade-offs between supply and environmental risks.
A static assessment building on Life Cycle Assessment (LCA) and Material Flow Analysis (MFA) showed that time delays, substitution effects, repercussions with the surrounding energy system and interactions between different CE approaches call for a more prospective and systemic assessment. Therefore, a scenario-based dynamic Energy and Material Flow Analysis is proposed as a suitable methodology for assessing the potential of CE approaches to reduce resource criticality. In this context, MFA and LCA methodology are coupled to quantify primary critical metal demand and energy-related greenhouse gas (GHG) emissions.
The developed methodological approach is explained by using the case study of electric vehicle batteries. A stock and flow model of the German mobility sector with a time frame until 2050 is extended by energy and material flows associated with the incoming and outgoing electric vehicles in each year. For the end-of-life (EoL) different scenarios are defined to show the effects of an increased recycling (rec) and an increased reuse/Second-Life (SL) of traction batteries in stationary battery applications, as well as the interactions between these two approaches. In the case of SL applications, also substitution effects in stationary battery markets are considered.
The comparison of the EoL scenarios shows that depending on the framework conditions SL applications can lead to trade-offs between the two criticality indicators “critical metal demand” and “energy-related GHG emissions”. While in the analysed case the SL application leads to a reduction in GHG emissions, an increase in cobalt demand is observed because of a delayed recycling process and the substitution of a less cobalt-containing technology (compare figure).
Figure: Effect of Second Life applications on energy related greenhouse gas (GHC) emissions and critical metal demand