New energy vehicles
A new energy vehicle is a very broad concept, which refers to a vehicle that uses unconventional energy, or uses conventional energy but uses a new power unit to convert energy and drive. New energy vehicles are generally more energy-saving and environmentally friendly, which is conducive to sustainable development.
In terms of energy sources, traditional cars use gasoline and diesel. The energy source of the new energy vehicle can be directly the electricity of the grid, or it can be some new fuels, such as natural gas, ethanol gasoline, methanol, dimethyl ether, hydrogen, biofuel, and so on. If it is a tram, the vehicle design will be completely different from the traditional fuel car. If fuel is still used, then the engine will be modified.
From the perspective of energy conversion, new energy vehicles can be divided into three categories: electric vehicles, fuel cell vehicles, and hybrid vehicles.
Electric car
If the external input electrical energy is stored in a chemical battery, this type of electric vehicle belongs to the chemical battery electric vehicle, Battery Electric Vechicle (BEV). The efficiency of trams is extremely high, generally above 85%. For decades, electric vehicles should only be equipped with lithium-ion batteries, because lithium batteries have high energy density, high charge-discharge rate, long cycle life, and stable high and low temperature performance.
An alternative that can be expected is solid-state batteries, which replace the liquid electrolyte in traditional lithium batteries with solid-state electrolytes to improve safety and energy density.
Fuel cell vehicle
If the fuel is directly converted into electricity in the vehicle, this type belongs to the fuel cell vehicle, Fuel Cell Vehicle (FCV). Compared with chemical cells, fuel cells have lower efficiency, about 40-60%, but they are still higher than ordinary engines. Fuel cell vehicles have been piloted on a small scale in California and on buses in some Chinese cities. Currently, the fuel cells that can be used in vehicles all use hydrogen as an energy source. However, hydrogen is extremely difficult to store and liquefy, so hydrogen storage containers are generally larger and heavier. This is also the reason why the pilot bus is used. Hydrogen can be obtained by electrolysis of water. Therefore, hydrogen can also be regarded as the carrier of electrical energy. The electricity generated by the power station is converted into the chemical energy of hydrogen, and then sent to the fuel cell vehicle, and then converted into electrical energy. Fuel cells using hydrocarbon fuels are still in the laboratory, and the technology is immature, mainly due to the shortcomings of high operating temperature, too expensive, and short life.
Hybrid car
A hybrid vehicle can refer to a vehicle powered by any two energy sources. For example, an electric vehicle equipped with lithium batteries and fuel cells can also be considered a hybrid vehicle. But generally speaking, a hybrid vehicle refers to a gasoline-electric hybrid. The engine and electric motor work together in some way to provide drive. With the cooperation of the motor, the engine can always be in the high-efficiency area, possibly reaching a thermal efficiency of 40% or even more than 50%. Hybrids will be the mainstay of cars for decades to come.
At this stage, there are two mainstream solutions for hybrid vehicles: hybrid hybrid vehicles and series hybrid vehicles.
Hybrid hybrid vehicle
One is a hybrid vehicle, the representative model is the Toyota Prius. The internal combustion engine and the electric motor in the Prius are connected together through a set of planetary gears. The internal combustion engine and the electric motor drive the tires at the same time. At the same time, the internal combustion engine can work in the best condition. Hybrid hybrid vehicles are more efficient, but complex and expensive.
Series Hybrid
Series hybrid, or extended-range electric vehicle. The representative model is the Chevrolet Volt. In this type of vehicle, the engine does not directly drive the wheels, the engine is only connected to the generator to generate electricity, and the generated electricity is used to drive the wheels. This type of configuration is relatively simple, but because the energy needs to be converted by the motor, the efficiency will be slightly lower.