Why are electric cars significantly more energy efficient than gasoline cars?
The difference between an electric car and a gasoline car is not only whether it is electric power or gasoline that is used to drive the motor, but there is also a big difference between the two in terms of 'energy efficiency'. In fact, the energy efficiency of electric cars is surprisingly high compared to gasoline cars, and the reason is summarized by Yale University's climate public relations site
Electrifying transportation reduces emissions AND saves massive amounts of energy » Yale Climate Connections
https://yaleclimateconnections.org/2022/08/electrifying-transportation-reduces-emissions-and-saves-massive-amounts-of-energy/
Electric Vehicles Are Way, Way More Energy-Efficient Than Internal Combustion Vehicles
https://www.motortrend.com/news/evs-more-efficient-than-internal-combustion-engines/
Karin Kirk, a geology and climatology writer, points out that internal combustion engines used in gasoline cars are fundamentally inefficient. Conventional gasoline cars waste about 80% of the energy contained in the fuel gasoline, and it seems that only about 20% of the energy is actually used to move the wheels forward.
Internal combustion engines are inefficient for thermodynamic reasons. The internal combustion engine heats liquid fuel to generate pressurized gas, which pushes the piston and turns the crankshaft to rotate the wheels. The energy that reaches the is limited.
Below is an image showing the energy wasted in a gasoline car and the energy reaching the wheels. Approximately 68-72% of the energy contained in gasoline becomes waste heat from the engine, 4-6% is used as power for the engine's cooling system, etc., and 3-5% is used for mechanical friction in drive mechanisms such as transmissions. Energy loss occurs. Also, up to 2% of the energy is used for auxiliary electrical components such as audio and lights, and only 16-25% of the total gasoline ultimately powers the wheels. In other words, even if you buy 5 liters of gasoline for about 800 yen, only 1 liter (about 160 yen) is used to move the car, and the remaining 4 liters (about 640 yen) are used elsewhere. It is consumed.
Fuel-efficient cars are lighter, smaller, and more aerodynamic, so they can make the most of the energy that reaches their driving components, but they can't avoid the structural energy losses of internal combustion engines. Is not ... “Even the most fuel-efficient gasoline vehicles cannot avoid these energy losses,” Kirk points out. says there is.
Electric vehicles, on the other hand, are propelled by a completely different system than gasoline vehicles. Energy is charged in the vehicle in the form of electricity and powers the drive components directly without being converted to another energy such as 'burning liquid fuel to gas'. Compared to an internal combustion engine, an electric motor has a structure with very few moving parts, and the
Below is a diagram showing the energy efficiency of an electric vehicle. Of course, some energy loss is inevitable even in electric vehicles, about 10% energy loss occurs when charging, about 18% is lost in the driving process and about 3% is lost in the cooling system etc. In addition, the amount of energy consumed by auxiliary electrical components is a maximum of 4%, which is slightly higher than that of gasoline vehicles, partly because it is difficult to use waste heat for heating in winter. However, the energy lost without reaching the driving parts is only 31-35%, and the energy recovery rate due to regenerative braking is 22%, so overall 87-91% of the charging energy is It will be the calculations used to move the wheels.
In the United States, 8.9 million barrels (about 1.415 billion liters) of automobile gasoline are used per day, but in terms of energy, about 80% of the total is wasted due to heat and friction. Only 1.8 million barrels (about 286 million liters) of energy is being used for propulsion. If all gasoline cars are replaced with electric cars, the total amount of energy consumed is equivalent to 2 million barrels of gasoline (about 318 million liters) at most, even if 11% energy loss is added, resulting in significant costs and energy. savings can be achieved.
Of course, energy loss also occurs when electricity is generated, so not all the energy contained in fossil fuels and nuclear power is converted into electrical energy. However, since power plants are more efficient than internal combustion engines in gasoline vehicles, the energy efficiency of coal/nuclear power plants is about 33%, natural gas power plants about 44%, and hydro power plants about 90%. It boasts a power generation efficiency of 10%.
Considering the energy efficiency at the power plant, the figure showing the energy efficiency in the electric vehicle is below. Energy efficiency is 31% for coal-fired power generation, 48% for natural gas power generation, and 75% for hydroelectric power generation, making it possible to convert energy into propulsion with efficiency that exceeds that of gasoline vehicles.
In addition, Mr. Kirk is also looking at the battery manufacturing process for electric vehicles, but the energy required for battery manufacturing is equivalent to about 74 gallons (about 280 liters) of gasoline, so if you switch to an electric vehicle It's a calculation that pays off.
While acknowledging that decarbonizing the world's energy is a huge and difficult task, Kirk argued that, at least in the automotive sector, the transition to electric vehicles could be a big improvement. “Electric vehicles can significantly improve driving efficiency, thereby reducing emissions of carbon dioxide and environmental pollutants, while also reducing overall energy demand. It's a win,' he said.
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