Engineering Papers on Hybrid Electric Propulsion Systems

Hybrid Electric Propulsion Systems


The term “Hybrid Electric Propulsion Systems” refers to systems that incorporate or supplement the existing energy engines use for propulsion with electrical energy. Most engines run on fossil fuels like oil or gas. Concerns about the emission of gases like CO2, and the effects of such emissions on the environment have instigated the need to find alternative environmentally clean sources of energy. One of the cheaper and cleaner sources is electrical energy. However, Engineers and scientists have been confronted with the challenge of inefficiency of rechargeable batteries and cells, in terms of power storage capacity and the length of time of discharge before recharge. One of the methods of getting around the problem is to supplement the would-be-fully-electricity-dependent propulsion systems with current methods of propulsion.



This short paper investigates the prospects of adoption of hybrid electric propulsion systems in terms of being a solution to global warming, and as a means of reduction of the cost incurred on fuel. It dissects the hybrid electric propulsion system, highlights its three main classes, and mentions some of its applications. The paper emphasizes the implementation of this technology as one of the measures against global warming, and as a means of saving costs.



Hybrid Electric Propulsion Systems is a technology that combines both electrical energy and any other form of energy (oil, gas, coal etc) to achieve propulsion in engines (Guzzella and Sciarretta 80). The system pools together an electric motor and the traditional combustion engine. In other cases, a generator is included as a third component of the system. Besides charging of batteries at charging stations, the energy that would have been wasted by the vehicle can be harnessed and stored in the batteries. Some more modern forms of this technology convert the energy that would have been wasted on breaking, to electrical energy, and stores it in batteries.



The principle of hybrid electrical propulsion systems can be implemented in submarines, trains and locomotives, scooters and trams, cranes, and construction machines. In their application in vehicles, the systems are classified into micro hybrid, mild hybrid, and fully hybrid systems (Pistoia 581).


Micro Hybrid Propulsion System

This form uses the least amount of electrical energy. It marries the starter and the alternator. The electrical motor used is only meant for starting and stopping. The energy economization of energy is obtained solely from the use of this electrical motor for that purpose. The price of this car is slightly higher than that of the conventional fully internal combustion engines. Chan states that a micro hybrid can save energy up to 2%-10% (592).





Mild Hybrid Propulsion System

In this case, the motor contributes to the propulsion. The motor is flatly shaped and it is directly coupled to the internal combustion engine. The high inertial of the electric motor, which it owes to its high-diameter-to-length-ratio design, facilitates easy removal of the original flywheel, allowing the motor to join in the propulsion. Chan states that a mild hybrid can save energy up to 10%-20% (592).


Full Hybrid Propulsion System

In this case, a motor, generator, and an engine are integrated in a complex architecture. Power split devices are used to optimize power flow among the three to achieve energy efficiency. The motor is used for start and stop; the engine alone can be used for cruising; or a collaboration of the motor and the engine can be used for abrupt acceleration or normal propulsion. When the engine is running optimally, the extra power that is not needed for propulsion is used to run the generator, which in turn charges the batteries, in which the energy stored will be used to run the motor when necessary. Chan states that a full hybrid can save energy up to 20%-30% (592).



Hybrid electric propulsion system has a number of advantages, some of them being of mechanical and engineering nature, such as optimization, flexibility, and accommodation of variable rpm. This paper looks at emission of harmful gases and cost saving.

Energy Cost Saving

As mentioned on the outlines, the technology can save a lot of energy. Users of full-internal-combustion-engine-reliant cars spend ‘extra’ money on same amount of energy. Massive amounts of money would be saved if hybrid cars were widely used.

Reduction CO2 emission

            The energy that would have been saved, as mentioned above, is supplied by fossil fuels in the case of internal combustion engine cars, leading to CO2 emission, which can be prevented. Since vehicles are among the highest emitters, this technology would reduce it massively.



In conclusion, the environmental and economical advantages of adopting or switching from vehicles that rely fully on internal combustion engines to those that use the hybrid electric propulsion system technology are of significance. Considering the difficult and uncertain economic times currently, and the threat and harm that global warming is causing to the environment and the ecosystem, this is the kind of technology that ought to be widely adopted if not fully switched to.















Works Cited


Chan, Ching-Chuen, Alain Bouscayrol, and Keyu Chen. “Electric, hybrid, and fuel-cell vehicles:

Architectures and modeling.” Vehicular Technology, IEEE Transactions on 59.2 (2010): 589-598.

Pistoia, G. Electric and Hybrid Vehicles: Power Sources, Models, Sustainability, Infrastructure and

 the Market. Amsterdam: Elsevier, 2010. Internet resource.

Guzzella, L, and Antonio Sciarretta. Vehicle Propulsion Systems: Introduction to Modeling and Optimization. Heidelberg: Springer-Verlag, 2013. Internet resource.