Energy transfers and Resources Flashcards
What does the Law of conservation of energy state
Energy can be transferred usefully, stored or dissipated but it cannot be created or destroyed.
what is a sankey diagram
Sankey diagrams provide an overview of the main energy flows and how they contribute to the global energy balance of a certain territory
is the total quantity of energy in the universe constant or changing
Constant
Why is it that during energy transfers in a closed system, there is no net change to the total energy
Like any other system, energy can be transferred in a close system. However, since energy cannot exchange with the surroundings, there will be no net change to the total energy in a closed system.
Wasted energy
Wasted energy is energy that is not usefully transferred
Wasted energy equation
Total energy - useful energy
Dissipation
Dissipation is a term that is often used to describe ways in which energy is wasted. Any energy that is not transferred to useful energy stores is said to be wasted because it is lost to the surroundings. Electrical cables warming up are a good example of this because it transfers thermal energy into the surroundings
what are 7 types of energy stores
Kinetic, Electrical, Chemical, Gravitational potential, Elastic potential, Thermal (Internal) and Magnetic
conduction
Conduction is the process by which heat energy is transmitted through collisions between neighboring atoms or molecules. Conduction occurs more readily in solids and liquids, where the particles are closer together than in gases, where particles are further apart.
Thermal Insulation
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way to stop unwanted energy transfer. A common way in which energy is wasted is through thermal energy. For example, when a house is heated, energy can be transferred through the windows, doors and walls. In order to combat this, houses are often insulated and windows are double glazed.
Lubrication
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way to stop unwanted energy transfer. Energy can be lost due to friction. a lubricant is a substance such as oil or grease that helps to reduce friction between surfaces.
control of friction
what happens when thermal conducticity of a material increases
The rate of thermal conductivity across the material will increase.
rate of cooling in buildings
thermal conductivity of doors, walls and windows can result in energy loss. Reducing thermal conducticity will reduce the amount of thermal energy leaving buildings.
one way it can be achieved is through increasing the thickness of walls, such as putting an airgap between layers in walls and potentially fill the airgap with foam to reduce the rate of thermal conductivity
metals are good conductors of electricity. True or False?
True
metals conduct at different paces, some are better than others.
what happens to the particles of a heated/warm solid.
if the solid is hot, the particles will vibrate. Due to the density of the particles, vibrations are easily moved on.
Thermal conductivity.
Definition not needed for GCSE syllabus but helps being known
Measure of rate of at which thermal energy transfers through a material
metals are good thermal conductors, wood, plastic and cotton are not
Energy Efficiency equation
Useful Power output / Total power input
Energy transfer efficiency equation
Useful output energy transfer / Total input energy transfer
How to achieve efficiency of an intended energy transfer.
This can be achieved by reducing wasted energy transfers so more of the input energy is usefully transferred. Mechanical devices can be made more efficient through lubrication to reduce the friction between moving parts of a machine and increase the amount of useful energy transferred.
The change in temperature of a system depends on:
the amount of thermal energy transferred to the system. the mass of the substance. the nature of the substance itself.
Specific heat capacity
The specific heat capacity of a material is the energy required to raise one kilogram (kg) of the material by one degree Celsius (°C).
Specific heat capacity of water
4,200 J/kg°C
specific heat capacity equation
change in thermal energy = mass × specific heat capacity × temperature change
E = m x c x delta theta
Delta theta is change in temperature
E measured in Joules
m measured in Kg
speficic heat capacity measured in joules per kg per degrees C
delta theta measured in degrees celsius
Electrical energy transferred equation
current x potential difference x time
examples of main energy resources
fossil fuels (coal, oil and gas), nuclear fuel, biofuel, wind , hydroelectricity, geothermal, tidal, solar and waves.
Renewable Energy resource
being or can be replenished as used - will never run out
Non renewable energy resource
a resource that is finite - will run out at some point
examples of non renewable energy resources
Coal, Oil, Natural Gas, Nuclear energy
5 examples of renewable energy resources
Biofuel, Geothermal, Wind, Hydroelectricity, Solar
(Tidal and waves also renewable)
Uses of energy resources
Transport, Electricity generation, heating etc.
Why are some energy resources more reliable than others?
The non-renewable sources are the most reliable as they can be used at any time. Whereas, the renewable sources normally depend on the weather. This means that if there is no wind, or no sun (night-time), or no waves then no electricity can be generated.
environmental impact of coal
coal burning is a major source of air pollution and emits greenhouse gases. Usage of coal can release substances that create acid rain.
environmental impact of oil.
oil spills can contaminate soil and water and cause fires, and is deadly to animals, and damages habitats.
Oil extraction can produce greenhouse gases.
environmental impact of natural gases
Natural gas can cause air pollution, contaminate water and releases methane.
environmental impact of nuclear energy
Can produce radioactive waste
problems with solar energy
Costly and weather dependent
problems with wave energy
disturbs seafloor, toxic chemicals
problems with tidal energy
high cost, negative affects on marine life
problems with wind energy
noise, could impact birds in wildlife
problems with hydroelectric energy
can cause environmental and social problems. Reservoirs drastically change the landscape and rivers they are built on. Dams and reservoirs can reduce river flows, raise water temperature, degrade water quality and cause sediment to build up. This has negative impacts on fish, birds and other wildlife.
problems with geothermal energy
Air and water pollution are two leading environmental issues associated with geothermal energy technologies. Requires a lot of water, can leave hazardous waste.
problems with biomass
can release harmful gases.
base load
Base load is the minimum level of electricity demand required over a period of 24 hours.
does demand for energy change within 24 hours
energy demand fluctuates throughout the day.
does demand for energy change within 24 hours
energy demand fluctuates throughout the day. different resources are used to meet the demand.
what do nuclear and coal power do
their stations take the longest to start and stop and are used to meet the base load
what do gas and hydroelectricity stations do
quick to start on and off, used at busy times
what else does remewable energy do
can be used at peak time or stored using pump storage schemes
2 ways to reduce unwanted energy transfer
Lubrication and Thermal Insulation
