杭州市公交车油改电项目碳排放效益核算

以减少碳排放为核心的应对气候变化行动已成为全球趋势,中国政府积极践行减少碳排放的国际承诺,出台多项鼓励新能源的政策措施,其中包括对新能源产业的补偿以及将燃油汽车改装为电动汽车。但是这些政策的实施效果并不太清楚。举例来说,煤电为主的供电类型极大削弱了碳减排的效果,充电桩等配套基础设施建设和旧车报废等过程还会产生额外碳排放,不同城市之间的这些情况差别也较大。因此,城市层面生命周期尺度上的电动车碳减排效果尚未明确。基于生命周期理论,以杭州市为例,在构建公交车生命周期模型下分别核算纯电动和柴油车生命周期碳排放量,并在基准情景、低碳情景和强化低碳情景下进行公交车油改电碳排模拟。研究结果表明:(1)杭州市单辆纯电动和柴油公交车生命周期CO2排放量分别为1103.237t和1401.319t,减排比例达21.27%。其中,电力生产约占纯电动车生命周期碳排量74.10%,柴油生产与消耗约占柴油车生命周期碳排量86.96%;(2)目前杭州市在营运的2312辆纯电动公交车生命周期内(13年)碳减排总量约达到68.917万t,年均5.301万t;(3)在油改电过程中,纯电动公交车需运行约3.5年后才能相对柴油公交车真正起到碳减排效果;(4)在不同新煤电技术及能源结构优化下,2020、2035和2050年杭州市公交车油改电项目每辆车碳减排量将达到354.071—884.339t,年均27.236—68.026t,减排比例25.27%—63.11%,且2050年强化情景下纯公交车生命周期碳排量仅为当前纯电动公交车和柴油公交车的46.86%和36.89%,潜在碳减排效益显著。

Carbon emission accounting for the transition of public buses from gasoline to electricity in Hangzhou City, China

As global climate change worsens, the goal of reducing carbon emissions has become a global consensus. The Chinese government has already taken a series of active policy measures to reduce carbon emissions, including compensation for new energy industries and for converting gasoline-fueled vehicles to electric vehicles. Electric vehicles are gradually becoming a viable alternative to gasoline-fueled vehicles, owing to their greater efficiency and lower pollution, including lower carbon emissions. However, empirical evidence of the environmental effects of such policy measures remains unclear. For example, the coal-based grid energy structure of China may largely offset the effectiveness of carbon emission reduction policies. Meanwhile, the construction of basic ancillary facilities (e.g., the construction of charging piles, and the scrapping or recycling of old vehicles) also introduce additional carbon emission and other environmental costs, which further reduce the effectiveness of carbon emission reduction policies. As a result, at the life-cycle scale, the effect of carbon emission reduction of electric vehicles is still controversial. We systematically assessed the carbon emissions of electric and diesel-fueled buses using the life-cycle assessment method and Hangzhou City as an example, and then simulated the carbon emissions of the buses under baseline, low-carbon, and strengthened low-carbon scenarios. Our results show that:(1) At the life-cycle scale, the carbon emissions of each electric and diesel bus were 1103.237 and 1401.319 t CO₂ eq, respectively, of which electricity production and fuel combustion accounted for 74.10% and 86.96%; (2) For the currently operating 2312 electric buses in Hangzhou, the total reduction in carbon emissions at the full life-cycle (13 years) is ~0.689×10⁶ tons, or an average of 53.013×10³ tons per year; (3) It takes ~3.5 years before the total net carbon emissions of electric buses to be less than those of diesel buses; (4) For the switch of diesel buses to electric buses program at Hangzhou City, under different development of new coal technologies and improvement of energy structure scenarios, in the years of 2020, 2035, and 2050, the reduction of carbon emission of single electric bus at Hangzhou is expected to reach 354.071-884.339 ts, with an annual reduction of 27.236 (25.27%) to 68.026 t (63.11%). Particularly, under the strengthened low-carbon scenario in 2050, the life-cycle carbon emissions of electric buses will be only 46.86% and 36.89% that of current electric and diesel buses, respectively. The results of our quantitative study suggest that, at the life-cycle scale, switching from diesel buses to electric buses can provide an appealing reduction in carbon emissions.