In many cities, diesel buses are being replaced by electric buses with the aim of reducing local emissions and thus improving air quality. The protection of the environment and the health of the population is the highest priority of our society. For the transport companies that operate these buses, not only ecological issues but also economic issues are of great importance. Due to the high purchase costs of electric buses compared to conventional buses, operators are forced to use electric vehicles in a targeted manner in order to ensure amortization over the service life of the vehicles. A compromise between ecology and economy must be found in order to both protect the environment and ensure economical operation of the buses.

In this study, we present a new methodology for optimizing the vehicles’ charging time as a function of the parameters CO_2eq emissions and electricity costs. Based on recorded driving profiles in daily bus operation, the energy demands of conventional and electric buses are calculated for the passenger transportation in the city of Aachen in 2017. Different charging scenarios are defined to analyze the influence of the temporal variability of CO_2eq intensity and electricity price on the environmental impact and economy of the bus. For every individual day of a year, charging periods with the lowest and highest costs and emissions are identified and recommendations for daily bus operation are made. To enable both the ecological and economical operation of the bus, the parameters of electricity price and CO₂ are weighted differently, and several charging periods are proposed, taking into account the priorities previously set. A sensitivity analysis is carried out to evaluate the influence of selected parameters and to derive recommendations for improving the ecological and economic balance of the battery-powered electric vehicle.

In all scenarios, the optimization of the charging period results in energy cost savings of a maximum of 13.6% compared to charging at a fixed electricity price. The savings potential of CO_2eq emissions is similar, at 14.9%. From an economic point of view, charging between 2 a.m. and 4 a.m. results in the lowest energy costs on average. The CO_2eq intensity is also low in this period, but midday charging leads to the largest savings in CO_2eq emissions. From a life cycle perspective, the electric bus is not economically competitive with the conventional bus. However, from an ecological point of view, the electric bus saves on average 37.5% CO_2eq emissions over its service life compared to the diesel bus. The reduction potential is maximized if the electric vehicle exclusively consumes electricity from solar and wind power.

在许多城市，柴油公交车被电动公交车所取代，目的是减少局部排放并因此改善空气质量。保护环境和人民健康是我们社会的最高优先事项。对于经营这些公共汽车的运输公司而言，不仅生态问题而且经济问题都非常重要。由于电动巴士的购买成本比传统巴士高，因此，运营商被迫有针对性地使用电动车辆，以确保在车辆使用寿命内进行摊销。为了保护环境和确保公交车的经济运行，必须在生态与经济之间找到折衷方案。

在这项研究中，我们提出了一种根据参数CO _2eq排放量和电费来优化车辆充电时间的新方法。根据记录的每日公交运营情况，计算2017年亚琛市客运的常规和电动公交车的能源需求。定义了不同的充电方案，以分析CO _2eq随时间变化的_影响强度和电价对公交车的环境影响和经济性。对于一年中的每一天，都要确定成本和排放最低和最高的充电期，并提出每日公交运营的建议。为了使公交车既环保又经济，对电价和CO ₂的参数进行了不同的加权，并考虑了先前设定的优先级，提出了几个充电期。进行了敏感性分析，以评估所选参数的影响并得出改善电池供电电动汽车的生态和经济平衡的建议。

在所有情况下，与以固定电价进行充电相比，充电时间的优化最多可节省13.6％的能源成本。CO _2eq排放的节省潜力相似，为14.9％。从经济角度来看，平均凌晨2点至凌晨4点充电将使能源成本最低。在此期间，CO _2eq强度也很低，但是午间充电可最大程度地节省CO _2eq排放量。从生命周期的角度来看，电动公交车与传统公交车相比在经济上没有竞争力。但是，从生态角度来看，电动公交车平均可节省37.5％的CO _2eq与柴油客车相比，其使用寿命内的废气排放量更高。如果电动汽车仅消耗太阳能和风能发电，则减排潜力最大。