Physics – 1.7.1 Energy | e-Consult

Explanation of Conservation of Energy:

The Sankey diagram shows the energy flow through different stages of the hydroelectric power plant: water source, potential energy, kinetic energy, turbine energy, generator energy, and electricity output. The principle of conservation of energy states that energy cannot be created or destroyed, only transformed from one form to another. In a closed system like this power plant (assuming negligible energy losses to the environment), the total energy entering the system must equal the total energy leaving the system. The energy entering is the potential energy of the water, which is transformed into kinetic energy as it flows down, then into turbine energy as it spins the turbine, and finally into electrical energy as it is generated. The total energy leaving is the electrical energy produced.

Calculation of Efficiency:

• Total Energy Entering: 150000 J/s (potential energy)
• Total Energy Leaving: 30000 J/s (electricity)
• Efficiency = (Useful Output Energy / Total Input Energy) * 100%
• Efficiency = (30000 J/s / 150000 J/s) * 100% = 20%

Therefore, the efficiency of the power plant is 20%.