Ecological lifecycle assessment of an electric drive for the automotive industry

The growing consequences of global warming and rising prices for fossil fuels are calling for a broad substitution of combustion engines by electrical machines and an energy- and resource-efficient design of manufacturing systems. The present work proposes a conceptual approach for the holistic product lifecycle assessment (LCA) of an electric drive for the automotive industry. The proceeding is part of the NRW Bank funded Project KERME (engl.: Competitive Electro-Mobility through Resource Efficiently and Modularly Designed E-Drives). KERME aims at the eco-efficient production of a scalable E-Drive, which finally enables the manufacturers to realize economies of scale, which in return is a key condition for a successful adaption of environmentally friendly transportation concepts by the end users due to reduced sale prices. The investigated electric drive will be designed to meet the load spectrum of a compact vehicle for close-by traffic in an urban environment. Accordingly, the engine is supposed to provide short but intensive phases of acceleration followed by long downtimes. Suitable engine concepts are the synchronous and asynchronous layout with an internal rotor and liquid cooling (P = 30 kW, nmax = 9000-12000 rpm, V = 300-400 V, dimensions (length × external diameter of box): 480 × 270 mm). Following the guidelines in ISO 14040/44, the analysis will determine the ecological impact of an E-Drive during all of the following lifecycle stages: Production of raw materials, manufacturing phase (including final assembly) and utilization phase. However, the focus of the analysis will be the manufacturing processes, completed by assumptions and mathematical models about the remaining phases. The analysis will break down the absorbed flows of resources and energy to the applied manufacturing processes per manufactured E-Drive. By doing so, the contribution of each production step to the over-all energy consumption, global warming potential or any other factor of ecological impact (e.g. eutrophication, eco- and human-toxicity) can be determined. Accordingly, those processes can be identified, which are the most promising to be modified in order to improve the energy efficiency of the production system and thus to lower the manufacturing costs while protecting the environment at the same time. In detail, the proposed work investigates the manufacturing and assembly of the main engine parts lamination stack, housing, rotor, stator and shaft. Thus, the E-Drive production includes a great variety of manufacturing technologies mentioned in DIN 8580: Primary forming (e.g. casting of housing), forming (e.g. stamping of magnetic strips in lamination stack), cutting (e.g. machining of shaft), joining (e.g. adhesive joint of box and stator), coating (electrical insulation of stator-grooves), modifying material properties (e.g. heat treatment of shaft). Physical measurement techniques will later be applied in order to determine the absorbed flows of electrical power, cutting fluids and material of each machine tool. By implementing and validating the production chain into a software tool (GaBi 5) possible scenarios with alternative manufacturing processes or materials can be analyzed concerning their impact on the ecological impact of the engine without conducting costly and time-consuming experiments.