Section 4: Energy resources and energy transfer

Question 1

Solar cells

Answer 1

Pro:

• Free and renewable
• No pollution
• Can generate electricity from photovoltaic cells

Con:

• uk sunshine unreliable and limited
• confined to daylight hours
• relatively expensive to manufacture

Question 2

Wind

Answer 2

Pro:

• renewable
• emission free and quick to build
• no fuel costs

Con:

• noise and visual pollution
• more expensive than fossil fuels
• wind levels fluctuate

Question 3

Tidal

Answer 3

Pro:

• renewable
• emission free
• predictable

Con:

• development costs
• harmful to aquatic life
• very few ideal locations

Question 4

Hydroelectric

Answer 4

Pro:

• renewable
• no CO2 emissions
• very cheap once dam has been built

Con:

• natural flow hydro reliant on rainfall and vulnerable to droughts
• pump storage relies on off peak electricity to pump water back uphill
• environmental and social impact of large dams

Question 5

Oil

Answer 5

Pro:
-reliable
-cheap to extract
-well established 
Con:
-CO2 emission
-non-renewable 
-price instability 
-reliance on politically unstable countries

Question 6

Nuclear

Answer 6

Pro:
-reliable and efficient 
-minimal CO2 emission after construction
-not vulnerable to price fluctuations
Con: 
-danger of nuclear waste, safety
-huge cost of building/ decommissioning reactor 
-planning/building takes years

Question 7

Biofuels

Answer 7

Pro:
-carbon neutral(carbon released balance carbon absorbed)
-suitable crops can be grown in UK
Con:
-space required to grow crops
-greenhouse gases in harvesting/transporting crops
-inefficient compared to fossil fuels

Question 8

Coal

Answer 8

Pro:

• cheap and reliable
• abundant, UK has large reserves
• decline of SO4 (acid rain) emissions last 29 years

Question 9

Gas

Answer 9

Pro:
-reliable 
-cleaner than coal
-lower CO2 emission 
-uk North Sea reserves
Con:
-significant CO2 emissions
-reserves running out fast so growing independence on imports and rising prices

Question 10

Landfill gas

Answer 10

Pro:
-burning it reduces methane(contribution to climate change)

Con:
-releases CO2 and nitrogen oxide gases

Question 11

Define work done

Answer 11

Work done = force applied x distance
(in joules) (Newtons) (metres)
W = F x d

Work done is when energy is transferred from one from to another. e.g lifting an object

Question 12

Gravity potential energy

• Equation
• change in GPE

Answer 12

GPE = m x g x h

(J) g) (10N/kg) (m)

When we do work to give an object GPE we are lifting it above Earth’s surface.

△GPE = m x g x △h

Question 13

Kinetic energy

Answer 13

-The amount of energy possessed by a moving object
-This depends on the mass and speed of the object
KE = 1/2 mv ²
KE = 1/2 mass x velocity ²
(J) (Kg) (m/s)

Question 14

Power

Answer 14

The rate of which work is done

P = W/t
Power = work done/time
watt) (J) (s
1 watt = 1 joule transferred/second

Question 15

Law of conservation of energy

Answer 15

Energy cannot be created/destroyed, only transferred from one form to another.

e.g Electric motor
electric→KE +( heat + sound)
wasted-dissipates into atmosphere

Question 16

Efficiency

Answer 16

Efficiency = useful energy output/ x 100
total energy input

Can be represented by a Sankey diagram

Question 17

Work done/GPE example:

1. Calculate the WD lifting a 5 kg brick 10m into the air
2. What’s its GPE?

Answer 17

W = F x d
The force we need is the weight of the object

force = 5 x 10 = 50N
WD = 50 x 10 = 500J

When i ve done the work the brick has GPE
△GPE = mg △h
5 x 10 x 10 = 500J
So the gain in GPE = WD

Question 18

What happens to wasted energy?

Answer 18

Every energy transfer produces heat which is dissipated into the atmosphere

(spreads out in air)

Question 19

Energy changes:

• electric motor
• recharging battery
• speaker
• microphone
• diving

Answer 19

• electric motor: electrical → kinetic + heat + sound
• recharging battery: electrical → chemical + heat
• speaker: electrical → sound
• microphone: sound → electrical
• diving: GPE → kinetic

Note: heat is always a product of energy transfer

Question 20

Energy in different forms

Answer 20

• Sound energy (particles vibration)
• Heat energy
• Light energy
• Chemical energy (burning fuels and food)
• Kinetic energy (moving objects)
• Nuclear energy (stored in the nucleus of an atom)
• Gravitational potential energy (objects above ground)
• Electrical energy
• Elastic potential energy/strain energy (stretched objects)

Question 21

Renewable fuel

Answer 21

Fuels produced from renewable resources that we have an infinite supply of

Question 22

Non-renewable fuel

Answer 22

Fues produced from non-renewable resources that we have a finite supply of

Question 23

What is a fuel

Answer 23

A concentrated source of energy

Question 24

Where are nuclear power stations built? Why?

Answer 24

Near a constant supply of water, in an isolated area

Because of their immense size and safety considerations

Question 25

What happens after 40-50 years to a nuclear power station?

Answer 25

It ends its productive life, and needs to be shut down in a process called decommissioning. This takes years and costs billions of pounds

Question 26

Demand for electricity

Answer 26

Varies from day to day. This can be predicted to an certain extent.

Question 27

Examples of a predictable demand for electricity

Answer 27

- surge in early morning/evening | - greater demand in winter than summer

Question 28

Examples of an unpredictable demand for electricity

Answer 28

- a storm | - break in-between a football match

Question 29

Start up time of different energy resources

Answer 29

Nuclear power station: Weeks (not stopped unless absolutely necessary ) Coal, Oil and Gas : typically a few hours Hydroelectric: seconds (particularly good for supplying at peak demand times ) Wind: depends on wind Tide: predictable when available

Question 30

Sankey diagrams

Answer 30

Check iPad

Question 31

What is energy?

Answer 31

Ability to do work