4th Class Power Engineering Part B Practice Exam 2025 - Free Power Engineering Practice Questions and Study Guide

The reason why using steam engines generally has lower efficiency compared to other energy sources lies in the thermodynamic cycles they operate on. Steam engines primarily convert thermal energy from steam into mechanical work, and during this process, there are numerous energy losses, such as heat loss to the environment and friction within the engine components.

The ideal thermal efficiency of steam engines is constrained by the Carnot efficiency, which is affected by the temperature difference between the heat source (boiler) and the heat sink (condenser). Many modern energy generation technologies, such as combined cycle plants or advanced gas turbines, can achieve higher efficiencies by utilizing the combustion process more effectively and recovering waste heat.

In contrast to alternatives, such as electric motors or more advanced engines that utilize electricity directly from renewable sources, steam engines often lag behind in overall operational efficiency. This lower efficiency translates into higher fuel consumption and greater environmental impacts, particularly when fossil fuels are the primary energy source for generating steam.