Electrification of transport is an important option to reduce greenhouse gas emissions. Although many studies have analyzed emission implications of electric vehicle charging, time-specific emission effects of charging are inadequately understood. Here, we combine climate protection scenarios for Europe for the year 2050, detailed power system simulation at hourly time steps, and life cycle assessment of electricity in order to explore the influence of time on the greenhouse gas emissions associated with electric vehicle charging for representative days. We consider both average and short-term marginal emissions. We find that the mix of electricity generation technologies, and thus, also the emissions of charging, vary appreciably across the 24-h day. In our estimates for Europe for 2050, an assumed day-charging regime yields one-third-to-one-half lower average emissions than an assumed night-charging regime. This is owing to high fractions of solar PV in the electricity mix during daytime and more reliance on natural gas electricity in the late evening and night. The effect is stronger during summer months than during winter months, with day charging causing one-half-to-two-thirds lower emissions than night charging during summer. Also, when short-term marginal electricity is assumed, emissions tend to be lower with day charging because of contributions from nuclear electricity during the day. However, the results for short-term marginal electricity have high uncertainty. Overall, our results suggest a need for electric vehicle charging policies and emission assessments to take into consideration variations in electricity mixes and time profiles of vehicle charging over the 24-h day.

中文翻译：

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未来情景下电动汽车充电的排放：充电时间的影响

交通电气化是减少温室气体排放的重要选择。尽管许多研究分析了电动汽车充电对排放的影响，但人们对充电的特定时间排放影响了解不够。在这里，我们结合了 2050 年欧洲的气候保护情景、每小时时间步长的详细电力系统模拟和电力生命周期评估，以探索时间对与电动汽车充电相关的温室气体排放的影响。 . 我们考虑平均和短期边际排放量。我们发现，发电技术的组合，以及充电的排放，在 24 小时内都有明显的变化。在我们对 2050 年欧洲的估计中，假设的白天充电制度比假设的夜间充电制度产生的平均排放量低三分之一到二分之一。这是由于白天电力组合中太阳能光伏的比例很高，而在深夜和夜间更多地依赖天然气电力。夏季月份的影响比冬季月份更强，白天充电导致的排放量比夏季夜间充电低二分之一到三分之二。此外，当假设短期边际电力时，由于白天核电的贡献，白天充电的排放量往往较低。然而，短期边际电力的结果具有很大的不确定性。总体，