how do hybrid-electric engines work and have much greater efficiency than standard gas engines?


how do hybrid-electric engines work and have much greater efficiency than standard gas engines?

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You need to burn energy when a car goes vroom. That energy is wasted when the car slows down or brakes.

Regenerate braking converts some of that lost energy into electricity to recharge your car battery.

Hybrid cars take it a bit further. Hybrid cars have a larger battery that charges from regenerative braking and when the combustion engine spins. Hybrid cars also have one or more electric motors in addition to the combustion motor to convert electrical power to motion.

This means that the combustion motor can be smaller since the electric motors also contribute, increasing efficiency. You also don’t need the combustion motor working when the car is stopped or when you don’t need the full power of the car, saving gas. Regenerative braking also allows you to reuse some of the energy which is why hybrid cars have better mileage in the city where you brake a lot vs. On highways.

Plug-in hybrids have even bigger batteries and electric motors, allowing you to go some distance on electric only.

Battery electric vehicles get rid of the combustion engine entirely.

An internal combustion engine uses fuel continuously while being on, it needs to make enough power to keep the oil pump, water pump and alternator running, otherwise the engine will be damaged.

Standard gas engines also need to be reasonably powerful throughout a wide RPM range, otherwise the engine would feel “sluggish” and unpleasant to drive (like a Toyota..)

Hybrid drivetrains allow the combustion engine to be switched off when not needed, immediately saving this idle fuel consumption part.

The second bit is that hybrid drivetrains have large enough batteries to use brake energy regeneration, so instead of throwing energy away whenever you need to move slower (or stop), this energy can be captured, stored and used again to accelerate.

Lastly, you can now optimise your combustion engine for very specific RPM, because the electric motor can smooth out the sluggishness, which allow you to burn the fuel more efficiently.

The absolute most efficient way of doing this same thing, is how diesel-electric locomotives do it, running big diesel generators (which are designed to operate at a peak efficiency RPM continuously) to make electricity, and then use that electricity to run electric motors to power the train’s motion. Now you don’t need big transmissions, lots of different gears, mechanical linkages that have friction losses, etc.

Hybrid electric engines have both a normal gas engine and an electric engine with a small battery (small for a car).

For standard cars, when they brake, they turn the car’s kinetic energy into heat, via the brakes; all that energy is wasted. For hybrid and electric cars, they use electric motor for regenerative braking, turning the car’s kinetic energy into electric energy stored in the battery. That energy is then used to accelerate the car with the electric motor.

Hybrid cars’ batteries are only large enough to store a few accelerations at a time, so it’s not going to get you far like a full electric car would, but it negates much of the gas car’s efficiency losses caused during stop-and-go’ing. So you’ll see hybrid cars with great city mileage, but only slightly better highway mileage.

Standard gas engines need to rev up and down in order to change your driving speed.
Engines do have a rotational speed at which they achive maximum efficiency and this speed is normally situated around a normal cruising speed. However, due to acceleration/deacceleration a standard gas engine is also working very often not at peak efficiency.

Hybrid-electric engines work differently.
They have 2 engines, a standard gas engine and an electrical engine (motor). These are coupled in such a way the driving speed is determined by a speed difference in gas engine and electrical engine.

This way, the gas engine can **always** operate at peak efficiency and the driving speed is determined by changing the rotational speed of the electric motor. This means a higher efficiency is achieved in such hybrid engines.

This video explains it all: