Life cycle assessment of electric motors - A systematic literature review

Electric motors account for over 53% of global electricity consumption, making their energy efficiency relevant for climate change mitigation and for a more competitive industry. However, more efficient motors often require more materials. Despite this, research primarily focuses on motors' energy efficiency during usage, neglecting other life cycle phase like manufacturing and disposal. This study conducted a Systematic Literature Review, identifying 1112 publications on the topic, with only 20 deemed relevant. Squirrel Cage Induction Motors (SCIM) were dominant due to their cost, reliability, and efficiency. However, over the past 30 years, efficiency has improved largely due to altered material use. This impacts production and disposal phases but lessens the use phase impact. Alternatives like Switched Reluctance Motors (SRM) provide better energy efficiency with fewer materials compared to SCIM. Permanent Magnet Synchronous Electric Motors (PMSM) emerge as the most energy efficient but with high environmental impacts in production and disposal. Synchronous Reluctance Motors (SynRM) are competitive SCIM alternatives, boasting less vol/wt, higher efficiency, and reduced impacts. The analyzed Life Cycle Assessments (LCAs) showed variations in included life cycle phases, materials accounted for, and impact categorization. Thus, a tiered framework for electric motor LCAs is recommended. The use phase has the most significant impact, accounting for over 90% of life cycle impacts. Efficient motors generally have reduced environmental effects over their lifespan, even if their production and disposal impacts are higher. Notably, all analyzed LCA publications are European, so findings might vary in other regions. The study concludes by highlighting seven research gaps to further reduce electric motors' environmental impacts.