Energy ProductionEnergy efficiency is the ratio or useful energy to input energy. efficiency = (useful energy / input energy) × 100For example, a solar panel that creates 300 watts of electricity from 1500 watts of sunlight:efficiency = (300 /1500) × 100 = 20%
Energy ConsumptionThe energy efficiency of a machine that consumes energy is calculated as the useful energy that is output by the machine as compared to the energy consumed. For example, an electric car that consumes 100 kWh resulting in 60 kWh of power to the wheels has efficiency of:efficiency = (60 / 100) × 100=60%Energy efficiency is always lower than 100% as machines always generate some waste such as the heat produced by an engine. Machine efficiency can be measured in terms of energy efficiency or the productive results of equipment. The latter approach uses the value of outputs and cost of inputs. In a month, a drilling machine takes inputs such as labor, electricity, materials and depreciation on the machine itself that cost 50,000 dollars. The machine produces parts with a value of 60,000 dollars.efficiency = (60,000 / 50,000) × 100=120%A newer machine drills holes 10 times as fast. The labour costs are the same and the machine wastes less electricity and materials. In a month, the machine consumes inputs of $410,000 and produces outputs with a value of $600,000. efficiency = (600,000 / 410,000) × 100=146%
|Overview: Efficiency Formula|
A measure of the efficiency of processes and machines.
efficiency = (output / input) x 100