Environmental impacts of a superconducting quantum computer based on a life cycle assessment

This master thesis investigates the environmental impact of superconducting quantum computers (SQCs), focusing on their global warming potential (GWP) throughout the production and use phases. The study is motivated by the rapid development of quantum computing technology and the need to evaluate its ecological footprint amidst growing concerns about greenhouse gas emissions. A life cycle assessment (LCA) was conducted to estimate the environmental impacts associated with the production and use of SQCs, using a coarse-grain methodology to analyse key subsystems. The analysis utilised the Ecoinvent database and was managed through the Activity Browser software, with a focus on GWP as the primary impact category, using the EF3.0 method. The findings reveal that the use phase of SQCs has a significantly higher environmental impact than the production phase, with refrigeration systems, particularly pulse tube cryocooler compressors, being the dominant contributors to CO$_2$ emissions. Over a five-year period, the total carbon footprint is estimated at approximately 50,000 kg CO$_2$-eq for a Belgian energy mix and 150,000 kg CO$_2$-eq for a global energy mix. The cryostat, largely due to its gold components, is identified as the subsystem with the highest impact during the production phase. The study concludes that while SQCs offer substantial technological advancements, their environmental impacts are considerable, particularly during the use phase. The research highlights the importance of optimising energy consumption and improving the design of refrigeration systems to reduce the ecological footprint of quantum computing. Further research is recommended to refine the LCA by examining specific subsystems in greater detail and exploring other databases for comparative analysis.