Efficiency

Key Concepts in Efficiency

Efficiency refers to how effectively a system or device transforms energy from one form into another.
Systems that are efficient waste less energy.
Energy is never lost; instead, it’s converted into less helpful forms, typically heat.
Mechanical systems often lose energy due to friction, which creates waste heat. Sound might also be an unwanted energy output.

Calculating Efficiency

Efficiency calculated using the formula: efficiency = (useful power output / total power input) x 100%
Note: In this formula, power refers to the rate of energy transformation.
The higher the percentage, greater is the efficiency. The maximum efficiency a device can have is 100%, though this is generally impossible due to unavoidable energy losses.

Energy Transfers and Efficiency

In an energy transfer, the useful energy is the energy converted into the desired form.
Remaining energy is generally converted into less useful forms, predominantly heat.
To identify the total energy input, add together the useful output and wasted output.
To increase the efficiency of energy transfers, we aim to maximise useful output and minimise wasted output.

The Law of Conservation of Energy and Efficiency

Efficiency is closely linked with the law of conservation of energy, which states that energy can neither be created nor destroyed, only transferred or transformed from one form to another.
This law suggests that total energy input is always equal to total energy output (including useful and wasted energy).

Real Life Examples

Insulation can improve the efficiency of a building by reducing heat loss.
Hybrid cars make use of regenerative braking to recover energy usually lost as heat.
Energy-saving lightbulbs convert a higher proportion of electrical energy to light energy compared to traditional lightbulbs. By doing so, they showcase higher efficiency.

Implications

Energy efficiency is a key consideration in the design of many technologies, from engines to home appliances.
Advancing energy efficiency can result in significant energy savings, reducing dependence on fossil fuels and cutting down carbon emissions.
Efficiency is not only a matter of energy saving; it’s also important for economic reasons as it encourages reduced energy usage and therefore lower costs.