Historical and future greenhouse gas emissions factors of critical materials for the information and communication technology sector

Sammanfattning

This thesis explores the development of greenhouse gas emission factors for the metals copper, gold, and silver historically and prospectively. This study aims to present the historical and current greenhouse gas emission factors and investigate the potential future development of the emission factors. This study uses a literature review to assess the current global average of emission factors to establish a baseline, then conducts scenario analyses on how the effects of variations in ore grade can impact the emission factors. An analysis using SimaPro was conducted by changing parameters such as the energy mix and diesel consumption on unit processes for copper, gold, and silver. Results from this study show a regional variation of emission factors between 2.5 and 9.96 kg CO2eq/kg Cu. For gold, regional differences between 4920 and 1,170,000 kg CO2eq/kg Au are presented. For silver, the differences are between 55.4 and 815 kg CO2eq/kg Ag. From the scenario analysis, it is possible to derive that ore grade has an inverse relationship with the emission factor of copper, gold, and silver, which entails increases in emission factors as the ore grade declines, and vice versa. The analysis using SimaPro demonstrates that a transition away from diesel reduces the emission factors, as long as it is to a renewable energy source like hydropower. To achieve greater reductions, the source of renewable electricity is a factor in decreasing the metals´ emission factors. Finally, the thesis concludes that the emission factors can be reduced by implementing renewable electricity to mitigate the electricity consumption of the most energy-intensive stages of the cradle-to-gate life cycle.