Conservation of Energy

The Principle of Conservation of Energy

• The principle of conservation of energy states that energy cannot be created or destroyed, but only transferred from one form to another.
• Hence, for an isolated system, the sum of the useful and wasted energy outputs will always be equal to the total energy input.

Efficiency

• When work is done, energy is always transformed into different forms of energy.
• For example if you were to lift a box, you would transfer chemical energy into gravitational potential energy and thermal energy (heat from your mitochondria burning fuel).
• Thermal energy in this scenario is not wanted and is counted as inefficiency.
• 100% efficiency is impossible as it would lead to perpetual motion. Imagine for example if you spun a cog, and it kept spinning forever. This doesn't happen in reality as the cog continuously loses kinetic energy as it is transferred into thermal energy and sound.

Sankey Diagrams

• Sankey diagrams can be used to show efficiency.