There are 9 types of energy:
The Law of Conservation of Energy states that energy cannot be created or destroyed; however, it can be transformed or transferred.
Machines transfer energy for a purpose. The only problem is that not all energy transferred is useful to us because it doesn’t always go where we want it in the form we wanted it in.
Energy Supplied = Useful Energy Delivered + Energy Wasted
Useful Energy Output
Device Efficiency = ----------------------------
Energy Supplied as Input
Efficiency can be visually represented by a Sankey Diagram (pictured above). No machine can be more than 100% efficient because we can never get more energy from a machine than we put into it. An inventor in 19th century America claimed to have made a machine that gave out useful energy without energy being supplied to it. It was later discovered he had a partner pedaling away beneath the ground to supply it with energy!