Posted 2020-04-30 09:08:30 +0000 UTC
Many people think that the energy flow of driving fuel vehicles is "oil gasoline", and the energy flow of driving electric vehicles is "power plant motor". However, a large proportion of power plants are thermal power generation. In China, for example, thermal power generation accounts for about 71% of the total power generation (2018 data), so this flow becomes "coal thermal power plant battery motor". The question follows: what is the environmental protection of coal-fired power generation? Does electric vehicles transfer pollution to thermal power plants? That sounds reasonable, but is it true? On March 28, nature sustainability, a subsidiary of nature, an authoritative journal of scientific research, published a paper on "the impact of electric vehicles and heat pump technology on global carbon emissions", which is called net emission reductions from electric cars and heat pumps in 59 world regions over time (click the original text at the bottom to read the full text). This paper discusses the impact of electric vehicles on global carbon emissions in three cases, including: (1) following the existing environmental protection technology trajectory; (2) following the environmental protection strategy agreed in Paris; (3) only applying the policy on transportation and heating, and abandoning the terminal environmental protection measures. Based on the data of 59 countries and regions around the world, the researchers of this paper prove through experiments and calculations that in the next 30 years, even if the electric power source of electric vehicles still needs a lot of fossil fuel (coal), it will reduce the global carbon emissions on the whole. In the worst-case scenario, electric cars are more environmentally friendly than gasoline cars in 95% of the world, said Florian Knobloch, one of the authors of the paper. The only exception is in places like Poland, where almost all of the electricity comes from coal and thermal power; while in countries like Sweden and France, most of the electricity comes from renewable energy and nuclear power, and the emissions of electric vehicles in the life cycle are 70% lower than those of gasoline vehicles. The point is that the researchers do not only study road emissions, but also evaluate the whole life cycle of electric vehicles, including the pollution gas emissions in the whole technology production chain and waste treatment process. According to the current technology trajectory, the paper predicts that the global average generation emissions (direct and indirect emissions per kWh) will decrease by 10% by 2030 and 16% by 2050 (compared with 2015); according to the Paris agreement development trajectory, the carbon intensity of the power industry will decrease by 44% by 2030 and 74% by 2050 (compared with 2015). Of course, the precondition of these prediction data is that in the future, pure tram will occupy the mainstream of social means of transportation. Assuming that by 2050, if all the roads are electric vehicles, the global carbon dioxide emissions will be reduced by 1.5 billion tons / year, equivalent to the total carbon emissions of Russia in a whole year. The paper also adds that since technology is constantly developing in any policy system, the proportion of energy and emission standards will change over time, and the proportion of clean energy has been rising (for reference, thermal power accounted for 80.3% of the total power generation in 2009 and 71% in 2018). In addition, technological progress will gradually improve the efficiency of energy utilization. Together, the two factors are expected to reduce the average emission intensity of electric vehicles by about 20% by 2030 (compared with 2015) and 30% by 2050 (weighted data). The derivation process of the paper may be a little complicated, but its conclusion is obvious - as long as the world's energy structure does not "regress" back to the state of 100% coal-fired power generation, the vehicle's electric propulsion is always conducive to reducing global carbon emissions. (in order to ensure the readability and simplify the relevant content of the paper, interested friends can click "original reading" to learn more about it.) Yes, even if the electric vehicle burns coal to generate electricity, it is also more environmentally friendly than the fuel vehicle, which solves this problem. Let's look at the other two derivative problems. Does electric vehicle "blame" vehicle pollution to your power plant? Yes, but the advantages outweigh the disadvantages. As we all know, every gasoline vehicle is a mobile pollution source. The road emissions it produces are random pollution, and the difficulty of its supervision and control is far higher than the fixed source emissions of power plants. Take unsightly chestnuts. Driving a fuel car is more like "peeing everywhere". Pollutants are everywhere, but driving an electric car is to go to the public toilets to manage the pollutants centrally. This is one of them. From the perspective of health, the exhaust gas of gasoline vehicles is road emission, which is usually diffused in the city center, that is, near the crowd emission, while the power plants are usually set in the suburbs, and the corresponding emissions are high altitude, and their impact on public health is not the same. Finally, the purification process of pollutants in the power plant is also different from that of the tail gas filtration on the gasoline vehicle. Although the gasoline vehicle is equipped with the "optimization" of three-way catalytic converter and fuel additive, the thermal power plant will carry out the desulfurization treatment of coal before combustion, and the desulfurization, denitrification, dust removal and other operations after combustion, so the purification efficiency is also very different. According to a 2007 study by MIT, in terms of the total number of people and health impact, the harm of 1 ton of harmful particles (PM2.5) emitted by automobiles is about 11 times that of 1 ton of harmful particles emitted by power plant chimneys. Let's talk about the second question. Is the power generation efficiency of burning coal lower than that of burning gasoline directly? Let's explain it mathematically. According to the national standard gb2589-81, the calorific value of standard coal combustion is 29271kj / kg. According to the national standard GB / t2589-2008 general rules for calculation of comprehensive energy consumption, the equivalent value of electric power is 3600kj / (kW · h). Based on the 100 km energy consumption of the model 3 long-range rear drive model, assuming that all the electric energy comes from the efficiency of thermal power generation (36.3%), the standard coal consumed in 100 km is equivalent to: (13kw · h × 3600kj / kW · h) / (29271kj / kg × 36.3%)= 4.40kg then let's look at the same level of fuel vehicles. Take 3 series as an example, the comprehensive fuel consumption is about 8-10l / 100km, take a middle value, 9L / 100km. According to the national standard GB / t2589-2008 general principles for calculation of comprehensive energy consumption, the efficiency of gasoline per kilogram is about 1.4714kg of standard coal, while the mass of 1l gasoline is 0.74kg. Then, the equivalent standard coal consumption per 100km of the same level fuel vehicles is 9L × 0.74kg/l × 1.4714 = 9.80kg equivalent standard coal 4.40kg and 9.80kg. From the perspective of unit energy consumption efficiency, the same level electric vehicles are still more environmentally friendly than the same level fuel vehicles. All of the above are inferences about "whether the electric vehicle is environmentally friendly" that we derive from theory. Some people may agree with and some people may disagree with it. But from our life experience, the final conclusion is that we are just ordinary people and will not live with the ideal of changing the world every day. We are exhausted by the car loan and house loan every month and the crowded bus to and from work every day. Therefore, although the proposition of "environmental protection" is valuable, it is still too far away from our life. Similarly, environmental protection is not the only purpose for the country to vigorously develop new energy. Our country's oil resources are limited, and there is no military force deployed in the oil producing areas around the world, so it is easy to get stuck in a situation. The emergence of electric vehicles is mainly to adjust the national energy structure, get rid of the dependence on single oil energy as much as possible. At the same time, we hope to establish new technical barriers in the future of the automobile industry, and realize the industry counterattack. There are national considerations in the country, and our consumers have their own. In the end, consumers are voting with hard-earned real gold and silver. We only hope that the products we buy are cheap and easy to use. Of course, if we are more "environmentally friendly", it is icing on the cake.
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