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P1 - Energy (Energy Resources and Their Uses (Non-Renewable Energy…
P1 - Energy
Energy Resources and Their Uses
Non-Renewable Energy Resources Will Run Out One Day
Fossil fuels
Coal
Oil
Gas
They'll all run out
They all damage the enironment
Provide most of our energy
Renewable Energy Resources Will Never Run Out
These are
The Sun
Wind
Water waves
Hydro-electricity
Bio-fuel
Tides
Geothermal
They'll never run out
Most do damage
Don't provide much energy
Energy Resources are Used for Transport
Non-Renewable Energy Resources
Petrol and diesel are made from oil
Coal is used in steam trains
Renewable Energy Resources
Vehicles can use bio-fuels
For Heating
Non-Renewable Energy Resources
Natural gas is used to heat homes
Coal is burnt in fireplaces
Electric heaters use energy from these resources
Renewable Energy Resources
Geothermal heat pump
Solar water heaters
Burning bio-fuels
Kinetic and Potential Energy Stores
Movement Means Energy in an Object's Kinetic Energy Store
Anything moving has a kinetic energy store
The energy depends on the object's mass and speed
Ek = 1/2mv*2 :warning:
Raised Objects Store Energy in Gravitational Potential Energy Stores
Lifting an object requires work
The amount of energy depends on mass, height and strength
Ep = mgh :warning:
Falling Objects Also Transfer Energy
Energy goes from gravitational potential energy to kinetic energy
Energy lost from the g.p.e. store = Energy gained in the kinetic energy store :warning:
Air resistance acts against them
Stretching Transfers Energy to Elastic Potential Energy Store
Ee = 1/2ke*2 :warning:
Reducing Unwanted Energy Transfers
Lubrication Reduces Frictional Forces
When something moves, there's usually a frictional force
Lubricants can reduce the friction
Heating Can Occur by Conduction and Convection
Energy is transferred to the kinetic energy store
Particles vibrate more and collide with each other
Thermal conductivity - how quickly energy is transferred through a material
In liquids the particles move faster so the space between each particle increases
The warmer and less dense region rises above the denser regions
Insulation Reduces the Rate of Energy Transfer by Heating
Have thick walls with low thermal conductivity
Use thermal insulation
Some houses have cavity walls
Loft insulation reduces convection currents
Double-glazed windows
Draught excluders reduce energy transfers by convection
Wind, Solar and Geothermal
Wind Power - Lots of Little Wind Turbines
Involves putting lots of wind turbines up
No pollution
Spoil the view
Very noisy
They stop when the wind stops
Initial costs are high
No permanent damage
Solar Cells - Expensive but No Environmental Damage
Solar cells generate electric current from sunlight
Often used in remote places
No pollution
Solar power is reliable in daytime
You can't increase power output
Initial costs are high
Used on a relatively small scale
Geothermal Power - Energy in Underground Thermal Energy Stores
Possible in volcanic areas
Brilliant free energy that's also reliable
Used to generate electricity
Aren't many suitable locations
Hydro-electricity, Waves and Tides
Hydro-electric Power Uses Falling Water
Usually requires flooding by building a dam
Big impact on the environment
Provides an immediate response
No problem with reliability excluding drought
Initial costs are high
Useful on a small scale in remote areas
Wave Power - Lots of Little Wave-Powered Turbines
You need lots around the coast
No pollution
Fairly unreliable
Initial costs are high
Tidal Barrages - Using the Sun and Moon's Gravity
Tides can generate electricity in lots of ways
Big dams built across estuaries
Produced by gravitational pull
No pollution
Pretty reliable, happen without fail
Initially costs are kind of high
Bio-fuels and Non-renewables
Bio-fuels are Made from Plants and Waste
Renewable energy resources
Supposedly carbon neutral
Fairly reliable, don't take long to grow
The cost to refine them is very high
Large areas of forest have been cleared to grow bio-fuels
Non-Renewables are Reliable
Fossil fuels are reliable
These fuels are slowly running out
The running costs aren't too expensive
Create Environmental Problems
They add to the greenhouse effect
Burning coal also releases sulphur dioxide
Acid rain can be reduced by removing sulfur
Coal mining ruins the landscape
Oil spillages cause serious environmental problems
Nuclear power is clean
Nuclear fuel is relatively cheap
Always carries the risk of catastrophe
Trends in Energy Resource Use
Currently we Still Depend on Fossil Fuels
The use of electricity hugely increased in 20th century
Now we use less because devices are efficient
Most electricity is produced with fossil fuels
Oil is used to fuel cars etc.
We are trying to increase renewable energy use
People Want to use More Renewable Energy Resources
Very damaging to the enivronment
Non-renewables will run out
Pressure from other countries has put limits in place
Car companies are affected by this attitude
The Use of Renewables is Limited by Reliability, Money and Politics
Lot of scientific evidence supporting them
Building renewable power plants costs money
Arguments over where to put power plants
Some energy resources aren't so reliable
Research on improving reliability takes time and money
Making personal changes can be expensive
Energy Stores and Systems
Energy is Transferred Between Stores
Thermal energy
Kinetic energy
Gravitational potential energy
Elastic potential energy
Chemical energy
Magnetic energy
Electrostatic energy
Nuclear energy
When a System Changes, Energy is Transferred
A system is one object or a group of objects
Can be transferred into or away from the system
Closed systems have a net energy change of zero
Energy is Transferred by Heating
Energy is transferred to water by heating, into the water's thermal energy store
Energy transferred electrically to chemical energy store
By Doing Work
Work done is just energy transferred
Work is done when current flows or force moves an object
Specific Heat Capacity
Different Materials Have Different Specific Heat Capacities
More energy needs to be transferred to thermal stores to raise the temperature
Materials need to gain lots of energy to warm up
Specific heat capacity - amount of energy needed to raise the temperature of 1kg of a substance by 1
change in energy = mc(change in temp)
You Can Investigate Specific Heat Capacities :star:
Block of material with two holes
Measure mass of block, wrap in insulating layer. Insert thermometer and heater
Measure initial temp and set pd to 10V. Turn on power supply and start stop watch
The current does work on heater from electric store to thermal store
Take readings every minute for 10 minutes
Turn off power supply. Calculate power supplied and how much energy is transferred
You can plot an energy transferred graph
Repeat with different materials
Conservation of Energy and Power
You Need to Know the Conservation of Energy Principle
Not all of the energy is transferred usefully into the given store
Dissipated energy is also called 'wasted energy'
Describe energy in closed systems
Energy can be transferred usefully, stored or dissipated, but can never be created or destroyed :warning:
Power is the 'Rate of Doing Work'
Power is the rate of energy transfer
Power is measured in watts
P = E / t :warning:
P = W / t :warning:
A powerful machine uses a lot of energy in a short time
Efficiency
Most Energy Transfers Involve Some Waste Energy
Useful devices can transfer energy from one store to another
Some input energy is usually wasted
The less energy wasted, the more efficient the device
You can improve efficiency by insulating objects
Efficiency = Useful power input / Total power input :warning:
Useful Energy Input Isn't Usually Equal to Total Energy Output
NO device is 100% efficient
Electric heaters are an exception
All energy transfers to thermal energy stores