Share the QR code < / P > < p > with wechat scanning code to friends and circle of friends < / P > < p > Chen Hong and Zhu Qigui < / P > < p > the world is paying attention to carbon emissions. At the just concluded G20 summit, leaders agreed to take "meaningful and effective" measures to achieve the goal of limiting global warming to 1.5 degrees Celsius. Emission reduction targets and timetables are being set all over the world. China has made the commitment of "reaching the carbon peak in 2030 and carbon neutralization in 2060" < p > with the rapid popularization of automobiles in China, controlling automobile carbon emissions has become particularly critical. The promotion of electric vehicles is regarded as an important measure to reduce carbon emissions. The state and local governments have introduced various subsidies and preferential policies for the manufacture and consumption of electric vehicles, and even provided scarce license plates to electric vehicle users. In fact, by increasing the proportion of electric vehicles and reducing the proportion of fuel vehicles, cities such as Shanghai and Beijing have indeed reduced carbon emissions (and some other exhaust emissions), making people feel the improvement of air quality < p > however, considering from the national level, the carbon emission reduction effect of electric vehicles is very limited. In some regions, such as North China and East China, it can not even compare with the fuel vehicles with the lowest carbon emission. The reason is that China's electric energy is mainly coal power generation, accounting for about 70%. According to the International Energy Agency (IEA), China emits an average of 580 grams of carbon dioxide per kilowatt hour, which is 123.5 grams in Canada, 295.8 grams in Germany and 352.5 grams in the United States. According to the 2019 "assessment report on greenhouse gas and air pollutant emission in vehicle life cycle" (hereinafter referred to as "vehicle emission report") of China's automobile life cycle emission assessment research working group, the carbon dioxide emission per kilowatt hour of electricity at the user end is 725g on average in China, 1318g in huabeiping and 840g in East China < p > to sum up, fuel vehicles can have lower carbon emissions than electric vehicles, but this advantage has several special preconditions: < / P > < p > first, the carbon emissions of electric vehicles are subject to the high carbon emissions of power generation, which is a major factor in China. If electric vehicles are in areas with low power generation emissions, such as Canada, it has the advantage of emission reduction. In addition, if electric vehicles can generate electricity using clean energy that can not be connected to the Internet (such as the roof photovoltaic power generation system of residential families), it has the advantage of emission reduction < p > Second, we chose to compare it with the most efficient fuel vehicle. Most fuel vehicles are far less efficient than Toyota's pure fuel hybrid Prius and have higher carbon emissions. According to the "automobile emission report", in general, the carbon emission of electric passenger vehicles is lower than that of gasoline passenger vehicles < p > Third, electric vehicles can significantly reduce carbon emissions in populous cities and exhaust emissions from other fuel vehicles, which is conducive to the health of citizens. A more comprehensive comparison should also include carbon dioxide emissions, emissions of other harmful substances, raw material supply and so on < p > based on the above analysis, we should have a clear understanding < p > first of all, it should be clear that the key to reducing carbon emissions is to reduce the carbon emissions of upstream production energy and power generation. Therefore, we need to vigorously develop renewable clean energy and gradually replace carbon fossil energy with renewable energy < p > Second, before the carbon emission of electric energy is reduced to a sufficient level, reducing the carbon emission of fuel vehicles should become one of the important transition routes. In particular, fuel vehicles should not be abandoned prematurely, and carbon emissions can be reduced by promoting energy-saving technologies such as fuel hybrid vehicles. We can make full use of the mature industrial chain of fuel vehicle production and manufacturing and its complete infrastructure (especially gas stations) < p > Third, the promotion of electric vehicles can not be one size fits all, but according to the specific domestic and regional conditions. Electric vehicles and small logistics vehicles in large cities can indeed improve urban air quality and support its development when they match the power grid capacity. For long-distance transportation between cities and countryside, the construction cost of charging infrastructure will be very high, which should be considered carefully < p > the fourth point is also one of the reasons supporting the previous proposal. The promotion of electric vehicles should be technically forward-looking and take full account of the emerging new technologies. In particular, we should consider that hydrogen energy vehicles, including fuel cell vehicles that have been promoted in Japan, the United States and Europe, and hydrogen diesel locomotives that have started in Europe, all have zero carbon emissions. Compared with battery electric vehicles, hydrogen energy vehicles have more advantages in heavy load and long-distance transportation. (Note: fuel cell vehicles directly convert hydrogen into electricity, so they are also electric vehicles.) < / P > < p > < p > it is noteworthy that at present, fuel cell vehicles realize hydrogen transportation, hydrogen storage and hydrogen supply based on high-voltage system. The main resistance to their development is the lack of hydrogenation infrastructure, because the cost of infrastructure is high and the safety is still in doubt. The latest technology being developed is a hydrogen energy vehicle based on liquid organic hydrogen storage. Because it is stored in liquid form at normal temperature and pressure, hydrogen transportation, storage and hydrogenation will be as easy as transportation, storage and gasoline, and the existing oil infrastructure can be fully utilized. When this technical route is mature, it will be able to achieve zero carbon emission and ensure safe and low-cost operation. It should also be brought into the vision of decision-makers for overall consideration < p > (the author Chen Hong is a professor of Shanghai School of advanced finance, Shanghai Jiaotong University, and Zhu Qigui is the party secretary of Shanghai School of advanced finance, Shanghai Jiaotong University)