When Would an Internal Combustion Engine Outshine an Electric Motor in Efficiency
In the era of electric vehicles and sustainable energy solutions, it is widely believed that electric motors outshine internal combustion engines (ICEs) when it comes to efficiency. However, the reality is more nuanced. There are specific situations where an ICE might be more efficient or more feasible, particularly in terms of the overall system efficiency, especially when considering various factors such as power supply availability and infrastructure.
The Fundamental Differences between ICEs and Electric Motors
At first glance, it may seem that an ICE and an electric motor belong to completely different domains. An ICE is a prime mover that generates power by burning fuel, while an electric motor only converts electrical energy into useful work. Therefore, from a purely conversion efficiency standpoint, an electric motor has a significant advantage. According to figures, an electric motor can achieve an efficiency of around 90%, whereas a diesel ICE has an efficiency of only approximately 45%.
Pure Efficiency vs. System Efficiency
However, the debate doesn't end there. Depending on the context, the most efficient approach can vary. When pure conversion efficiency is at the core of the assessment, an electric motor unequivocally wins. Nonetheless, the overall system efficiency, which includes the efficiency of power transmission and the feasibility of the entire system, must also be considered.
Transmission Losses and Power Distance
One critical factor that often brings the efficiency of electric motors down is transmission losses. For example, if an electric motor is situated far from its power source, the inefficiency due to transmission losses can be as high as 8-15%. This makes it crucial to assess whether it is practically feasible to supply power to the location. If power lines are not an option or if the cost of installing them is prohibitive, the use of an ICE might be more practical.
Feasibility in Remote Locations
In certain remote areas, particularly in industries like maritime transport, the choice between an electric motor and an ICE can be heavily influenced by feasibility. For instance, powering a cargo ship with shore power and an electric motor might be a practical solution in some contexts. However, such an approach can be logistically and financially challenging. In such scenarios, using an internal combustion engine can be more efficient from an overall system perspective, especially when considering the logistical challenges of refueling and power transmission infrastructure.
Economic and Infrastructure Considerations
Another factor to consider is the source of the power. If the power source is crude oil, an ICE might be more efficient than converting the oil into electricity with generators. This is because the energy conversion process with generators can lead to additional inefficiencies. Instead, using an ICE directly to provide mechanical work can be more efficient and straightforward.
Conclusion
The choice between an internal combustion engine and an electric motor is not one-size-fits-all. While electric motors generally win in terms of conversion efficiency, the overall system efficiency, feasibility, and the context of the application can determine which option is more suitable. From powering remote radio repeaters to operating cargo ships, the decision should balance pure efficiency with the practical and economic considerations of the specific situation.