Chapter 9

Question 1

What is affluence

Answer 1

• higher income enables people to buy more, consume more and use more energy in activities such as travelling more, heating a larger home and having more energy using appliances

Question 2

How are energy supplies important in the development of a society?

Answer 2

1) agriculture and fisheries
-fuel for machinery e.g tractors, water pumping, or fishing boats
-manufacture of chemicals e.g, for fertilisers
-storage e.g refrigerators for food

2)industry
- heat for baking e.g pottery, or bricks
-water treatment for public supply
Sewage treatment

3) domestic energy use
-space heating
-lighting
-Running appliances e.g washing machine

4) Transport
-transport of goods; ships, trucks, pipelines
-transport of people; cars, buses, trains

Question 3

What is abundance ?

Answer 3

Abundance measures the amount of the resource that exists.
-This isn’t the same as the amount available for use as there are many factors that restrict availability. For example:
1) fossil fuels that are deep underground and cannot be extracted
2) low intensity sunlight that cannot produce high temperatures

Question 4

What is energy density?

Answer 4

It’s a measure of the amount of energy in a given mass of energy resource e.g oil or coal
- in general, high energy density energy resources are most useful because:
1) smaller quantities are needed so storage and transport are easier
2) it’s easier to reach high temperatures

Question 5

What is intermittency?

Answer 5

If an energy resource is not available at times when it is needed then it is difficult to rely on it, for example wind, solar, or tidal energy

Question 6

Locational constraints

Answer 6

-energy resources are not evenly distributed.
-energy sources that can only be accessed via extraction (such as fossil fuels) must be located in favourable deposits
-energy sources that harness natural processes may depend on regional or local features including climate or topography

Question 7

Need for energy conversions

Answer 7

-the form of which energy is harnessed is not necessarily the form in which it will be delivered to the end-user
—for example, the chemical energy of fossil fuels is converted to heat, potential, kinetic, then electrical energy before it can be used to power electrical appliances

Question 8

What impact does resource exploitation have before the use of the energy?

Answer 8

1)fuel extraction
-coal mining, oil extraction
2)fuel processing
-coal, crude oil
3)equipment manufacturing
-exploitation of energy resources requires equipment that causes environmental damage
4)site development
-preparing sites for equipment causes habitat damage
5)transport
-the transport of of fuels uses fossil fuels
6)embodied energy in equipment
-equipment manufacture for every energy resource uses energy

Question 9

What are the impacts of use

Answer 9

1)pollution
-atmospheric pollution
- oil pollution
-radioactive waste
-noise pollution
-thermal pollution

2) habitat damage
- during extraction of the energy resource
-power station location
-ecological impact of HEP
-ecological impact of tidal power schemes
-pipelines and cables

Question 10

What is resource depletion

Answer 10

-fossil fuels provide most global energy supplies but they are non-renewable. Their availability must decline in the future as reserves deplete

Question 11

What is nuclear fission ?

Answer 11

-it involves the splitting of the nuclei of large atoms by neutron bombardment

Question 12

How do plutonium reactors work?

Answer 12

-0.7% of the uranium ore used in nuclear is uranium235. The remaining 99.3% is uranium238 which is not fissile (meaning it cannot undergo fusion)
-however uranium238 is fertile meaning it can be converted into a fissile isotope
-after neutron bombardment uranium238 is converted into the fissile Plutonium239. This takes place in a fast breeder reactor

✅allows much more energy to be produced then was originally mined
❌breeder reactors are more complex and expensive to operate

Question 13

What are fertile fuels

Answer 13

An isotope that isn’t fissile can be converted into a fissile fuel by neutron bombardment

Question 14

How do thorium rectors work?

Answer 14

-thorium232 isn’t fissile, however it’s a fertile fuel so it converted into the fissile Uranium233 once bombarded with neutrons

✅thorium is three times more abundant then uranium
✅it’s more difficult to make weapons then it is with uranium
✅much less radioactive waste it produced
❌breeding rate for uranium233 is slow so the fuel is expensive
❌uranium233 is hazardous as it releases alpha radiation

Question 15

What is nuclear fusion

Answer 15

-It involves the joining of the nuclei of small atoms
-it’s the energy source of all stars but producing controllable fusion on a small scale on earth is difficult

Question 16

What are the causes of fluctuations in energy storage?

Answer 16

1) use of intermittent energy resources, for example solar power, wind power, tidal power
2) bulk delivery of transported energy resources, for example, oil, coal, biofuels

Question 17

What are the causes for fluctuations in energy demand?

Answer 17

1)short term weather-related fluctuations
2)seasonal fluctuations
3)weekday/weekend fluctuations in industrial use
4) 24hr day/night fluctuations
5) short term behaviour related fluctuations: mealtimes, TV ‘pickup’

Question 18

What is peak shaving?

Answer 18

-Surplus electricity is used to pump water uphill, which stores the energy as gravitational potential energy.
-GPE can be converted to kinetic energy through water flowing to the lower reservoir turning the turbines and generating electricity to meet any peaks in demand

Question 19

What are the actors affecting rechargeable battery viability?

Answer 19

1) the efficiency of the storage cycle: percentage of the electricity used during recharging that is available later
2) the number of charge-discharge cycles that can be carried out
3)energy density
4) recharging speed
5) safety issues; toxicity, fire risk

Question 20

What is compressed gas

Answer 20

-surplus energy can be used to drive a pump that compresses air.
-The compressed air can be released later to power machinery

Question 21

What is the vehicle to grid (V2G) system

Answer 21

-these are systems where energy can be transferred between the national grid and and vehicle batteries.
-the proposal is that all vehicles are plugged into the grid where they are parked for long periods.
-if there’s a peak in the demand for electricity then a small proportion of the energy from the vehicle batteries is used
-this avoids the cost and environmental impacts of using rapid response, high cost power stations.

Question 22

What is the power to gas (P2G) systems?

Answer 22

-these use surplus electricity to produce gaseous fuel which can be stored
-water is electrolysed to produce hydrogen
-this can be used to produce methane that can be fed into the natural gas pipe network

Question 23

What is the hydrogen economy

Answer 23

-Storing excess energy helps address the disadvantages of energy resources which are only available intermittently
-those advocating hydrogen storage argue that it enables communities to be fuelled renewably from an abundant, convenient energy.
- this is known as the hydrogen economy
-the stored hydrogen would be used directly to power heating and vehicles or fuel cells to generate electricity
-unlike many renewable energy resources, hydrogen has a high energy density and therefore could replace fossil fuels for many uses, such as powering vehicles

Question 24

Transport energy conservation: aerodynamics/hydrodynamics

Answer 24

-reducing friction as a vehicle moves through the air or water reduces the amount of energy needed to propel it

Question 25

Transport energy conservation: reduced mass

Answer 25

Reducing the weight of a vehicle will reduce fuel consumption. This can be done in many ways:
1) redesigning wiring routes so that shorter cables are used and the wiring is lighter
2) replacing cast iron engine blocks with lighter aluminium ones
3) steel alloys containing carbon, titanium and vanadium create high strength steel so that thinner, lighter body panels can be used.

Question 26

Transport energy conservation: wheel design

Answer 26

-as air filled or ‘pneumatic’ tyres rotate, the weight of the vehicle squashes the tyre changing its shape
-when the vehicle moves frictional heat is created by this continual change in tyre shape and the movement of air inside the tyre
-less energy is lost by using solid wheels but these give a bumpy ride .

Question 27

Transport energy conservation: kinetic energy recovery systems (KERS)

Answer 27

-to slow a vehicle down, it’s kinetic energy must be converted into another energy form
-conventional braking systems use friction brakes to convert the KE to heat, which is lost to the atmosphere
-regenerative braking systems convert the KE to an energy form that can be used or stored rather than being wasted.

Question 28

Transport energy conservation: bulk transport

Answer 28

-carrying larger loads on fewer vehicles is more efficient than using a large number of small ones
-although more energy is used to move the larger vehicle the larger load it can carry is likely to give it a greater overall efficiency

Question 29

What are the Transport infrastructure and management systems?

Answer 29

1) integrated transport systems road/rail/cycle
- the most energy-efficient method of transport is not necessarily the same for the whole length of a journey but it is often inconvenient to change vehicle during a journey.

2) active traffic management (ATM)
- variable speed limits can be used to prevent the serious congestion that causes delays and wastes energy

Question 30

Vehicle design for end of life

Answer 30

-use of recyclable materials where possible
-easy identification of components and their composition
-east dismantling and separation components

Question 31

Building design : orientation

Answer 31

-energy losses are generally greater through windows than through walls but the solar grains through a window depend upon its orientation in relation to sunlight
-In the norther hemisphere, passive solar gains through windows are greatest through south-facing windows, while losses are greatest on the north side of the building
-the choice of position of different room types can reduce overall energy use. Rooms that need to be warmer may be placed on the side of the building that has greatest passive solar gains

Question 32

Building design: surface area

Answer 32

-the shape of a building and whether neighbouring buildings are joined affects the surface area through which heat can be lost.
-buildings with a low surface area:volume ratio will lose heat less easily

Question 33

Building designs: high thermal mass material

Answer 33

-temperature management in buildings can involve resisting periods of over-heating and periods of low temperatures.
-using materials with a high thermal mass can help to reduce temperature extremes. They can absorb heat to reduce over heating or emit heat to reduce heating requirements
-concrete and water both have high thermal masses

Question 34

Building design, choice of materials: low embodied energy materials

Answer 34

-many buildings require large amounts of cement for mortar and concrete. The manufacture of cement requires a lot of energy so buildings that use cement have a high embodied energy
-alternative materials that have lower embodied energy’s include :
— limecrete as an alternative to concrete
— rammed earth is an alternative to concrete block walls

Question 35

Building design, choice of materials: earth sheltered buildings

Answer 35

• during cold weather the ground is usually warmer than the air and the flow of the air over a building increases heat losses.
  -sinking some of the building into the ground can reduce heat losses.

Question 36

How do different materials reduce heat losses

Answer 36

1) double/ triple window glazing
— multiple layers of glass with spaces between them reduces the energy loss through windows. The gaps should be as large as possible, but not too large that convection currents can start

2) low emissivity glass
— has a surface coating that reflects long wavelength infrared energy back into the building

3) inert gas double/triple glazing
— glazing which has the gap between panels filled with inert gases is more expensive but it has lower thermal conductivities

Question 37

What are different energy management technologies

Answer 37

1) occupancy sensors
— they detect sources of infrared energy and movement. However, they truer appliances off if they cannot detect occupants in the room

2) automatic ventilation
— large glazed areas increase passive solar gains. This may be excessive during very sunny weather

3) improved insulation
— most insulating materials reduce conduction by trapping airspace’s in a porous structure. The most effective systems often have prefabricated boards with a reflective foil layer to reflect infrared radiation

4) heat exchangers
— can be used for ventilation with minimal heat losses. The heat of the air leaving the building is passed to the air coming in. The counter current flow of stale and fresh air in the heat exchanger ensures efficient heat transfer.

Question 38

Low energy appliances

Answer 38

1) lightbulbs
— CFL lamps replaced with LED lights

2) washing machines
— low energy washing machines have:
*faster spin cycles so the clothes need less drying
*cold and low temperature wash cycles which use less energy to heat water

Question 39

What are different ways of heat management

Answer 39

1) high volume of storage
— surface area is an important factor affecting heat loss
—reducing the SA by using a large tank rather than multiple small tanks to store hot fluids will reduce heat loss.

2) heat exchangers
—can be used for ventilation with minimal heat losses. The heat of the air leaving the building is passed to the air coming in. The counter current flow of stale and fresh air in the heat exchanger ensures efficient heat transfer.

3) combines heat and power (CHP) systems
—CHP power stations recover much of the heat lost in electricity generation and uses it for space heating in buildings, for example homes or fish farms

Question 40

Electricity infrastructure management

Answer 40

1) peak shaving
— involves the storage of surplus energy so that it can be used later, to meet demands if other supplies drop or to meet a peak in demand.

2) high voltage grid
— the resistance to the flow of electrify in a cable causes a loss of electrical energy as it is converted into heat which is lost from the cable

3) IT management of electrify supplies
— IT systems make it possible to accurately predict demand for electricity and monitor and adjust electricity supplies quickly. This reduces the waste of energy caused by generating electricity for which there was no demand

4) location of the new generation capacity and distribution infrastructure
— the electricity generating equipment that is used in the future may be in new locations, for example, offshore wind farms rather than power stations of coalfields.