Fakultät 07 / Institut für Elektrische Energietechnik
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To realize a reliable and cost-effective application of high-temperature superconductive (HTS) equipment at high-voltage (HV) levels, the influence of thermally induced gas bubbles on the dielectric strength of different solid insulating materials in liquid nitrogen (LN2) was investigated. A heatable copper tape electrode arrangement was developed simulating HTS tapes with insulation in between. AC breakdown measurements were performed without and with forced boiling on insulating papers, polypropylene laminated paper (PPLP) and polyimide (PI) films. Under nucleate boiling the influence of bubbles on the dielectric strength of all materials was not significant. However under film boiling the dielectric strength of the insulating papers decreased to a level comparable to their dielectric strength in air, demonstrating the insufficient impregnation of porous materials under film boiling. For PI there was no degradation at all. PPLP retained about 70% of its basic dielectric strength in LN2.
This paper presents a life cycle assessment (LCA) of photovoltaic (PV) solar modules whichhave been integrated into electric vehicle applications, also called vehicle integrated photovoltaics(VIPV). The LCA was executed by means of GaBi LCA software with Ecoinvent v2.2 as a backgrounddatabase, with a focus on the global warming potential (GWP). A light utility electric vehicle (LUV)named StreetScooter Work L, with a PV array of 930 Wp, was analyzed for the location of Cologne,Germany. An operation time of 8 years and an average shadowing factor of 30% were assumed.The functional unit of this LCA is 1 kWh of generated PV electricity on-board, for which an emissionfactor of 0.357 kg CO2-eq/kWh was calculated, whereas the average grid emissions would be 0.435 kgCO2-eq/kWh. Hence, charging by PV power hence causes lower emissions than charging an EV bythe grid. The study further shows how changes in the shadowing factor, operation time, and otheraspects affect vehicle’s emissions. The ecological benefit of charging by PV modules as compared togrid charging is negated when the shadowing factor exceeds 40% and hence exceeds emissions of0.435 kg CO2-eq/kWh. However, if the operation time of a vehicle with integrated PV is prolonged to12 years, emissions of the functional unit go down to 0.221 kg CO2-eq/kWh. It is relevant to point outthat the outcomes of the LCA study strongly depend on the location of use of the vehicle, the annualirradiation, and the carbon footprint of the grid on that location.