1.1 Energy
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21 Terms
System
An object or group of objects; when a system changes, the way energy is stored also changes
Specific Heat Capacity
The energy required to raise the temperature of 1 kg of a substance by 1°C or 1 K
1 watt
An energy transfer of 1 joule per second
Conservation of Energy
Energy can be transferred usefully, stored or dissipated but cannot be created or destroyed
Dissipated energy
Energy stored in less useful ways during system changes; often described as 'wasted'
Lubrication
A method of reducing energy waste (e.g. oil in a motor) by reducing friction, so less energy is lost as heat
Thermal Insulation
A method of reducing energy waste (e.g. double glazing) by reducing useful thermal energy lost
Thermal Conductivity
The higher the thermal conductivity of a material, the more easily heat travels through it and the higher the rate of energy transfer by conduction
Efficiency
The ratio of useful energy output to total energy input; efficiency = useful energy output ÷ total energy input = useful power output ÷ total power input
How to increase efficiency
Reduce waste output (lubrication, thermal insulation) or recycle waste output (e.g. reusing thermal waste as input energy)
Non-renewable energy sources
Fossil fuels (coal, oil, gas) and nuclear fuel
Renewable energy sources
Biofuel, wind, hydro-electricity, geothermal, tidal, solar, water waves
Renewable energy
Energy that can be replenished as it is used (e.g. wind will never stop)
Why non-renewables dominate large-scale supply
They produce a large energy output per kg of fuel; renewables cannot match this as easily
Reliability issue with renewable energy
Solar doesn't work at night or in bad weather; wind is only intermittent
Main uses of energy
Transport, electricity generation, and heating
Environmental impact of fossil fuel extraction
Involves destroying landscapes
Environmental impact of fossil fuel use
Releases harmful emissions
Environmental impact of solar and wind energy
Generate electricity directly with no emissions
Why fossil fuels rose to prominence
During the industrial revolution they were easy to mine and provided a large amount of energy
Why renewable energy has grown recently
Technology has developed to harness renewables efficiently, and fossil fuels have a finite lifetime