Past Paper questions

Question 1

List 4 uses of fossil fuels in modern day life

Answer 1

Any of the below:
Energy generation
transport 
plastics
fibres
pharmaceutics

Question 2

Explain the term: Fossil fuel

Answer 2

Fossil fuel – fuel consisting of the remains of organisms preserved in rocks in the earth’s crust with high carbon and hydrogen content.

or a non-renewable fuel source used for combustion. (examples include: coal, oil and natural gas)

Question 3

Explain the term: Renewable energy source

Answer 3

Renewable energy source – a form of energy derived from natural sources that do not use up natural resources to harm the environment.
(examples include: wind, tidal, hydro and solar)

Question 4

Explain why global action against the consumption of fossil fuels and climate change is required.

Answer 4

Conservation is triggered by a realisation that the worlds non-renewable resources are diminishing and that countries are using fossil fuels at a faster rate especially in emerging economies e.g. China, India
Climate change has been linked to increasing use of fossil fuels.
Global action is needed because the impact of excessive resource use affects the whole world.

Question 5

State 4 pieces of evidence linking the combustion of fossil fuels to climate change.

Answer 5

Weather patterns (Floods, Increased storms and famines).
Sea temperature rises.
Ecology changes.
Polar Ice caps melting.
Rise in sea levels.

Question 6

What government approved document in corporates the evidence linking combustion of fossil fuels to climate change.

Answer 6

(IPCC) intergovernmental panel of climate change 2007 report

Question 7

Identify and describe the advantages of carbon trading

Answer 7

Environmental: the process benefits the environment by pushing focus to renewable energy and away from fossil fuels
Control: the country or nation within the trading scheme will control the results produced and submit them personally.
Financial incentive: for complying with the trading scheme, there is a financial profit provided to the companies by selling the documents provided by the carbon trading scheme.
Flexibility: the nations methods of reducing carbon emissions are decided by the nation itself.

Question 8

Identify and describe the disadvantages of carbon trading.

Answer 8

Economy: depending on the nation, its economy may suffer greatly from large amounts of funding going towards these environmental projects and so could affect the economy as a whole.
Complexity: for poorer countries it will be difficult to apply these energy efficient methods.
Measuring: since the nation itself is alone responsible for its produced results, they are susceptible to fraud or modification by the nation.
Size of credits: nations may alter their submitted results to achieve financial incentive out of greed.

Question 9

Name two major drivers of an increase to electrical energy

Answer 9

electric cars

electrical heating systems for households

Question 10

Why has the global demand for renewable energy technologies increased in recent years.

Answer 10

Increase in world population.

Increase in the use of goods / materials.

Increased travel.

Decrease in fossil fuel sources.

Question 11

Identify 3 emerging economies that contribute to global carbon emissions and why they do so.

Answer 11

Brazil: increased demand of electrical energy due to Olympic games
India: large demand to construct further building and hospitals to compensate for growing population and healthcare
China: more rapid use of fossil fuels due to large economy and high population.

Question 12

Define the law of conservation of energy

Answer 12

energy cannot be created or destroyed but can be converted into other forms.

Question 13

Combined heat and power (CHP) is also known as:

Answer 13

Co-generation

Question 14

Identify the advantages of a CHP boiler system in comparison to a traditional power plant.

Answer 14

80% more efficient than traditional plants.
Less power losses as it will be located close to the user.
Makes use of wastage heat.
Uses less fuel in comparison to a traditional power plant.
Co2 emissions reduced by 30%
Reduced fossil fuel consumption.

Question 15

Define micro-generation and give 2 micro-electricity technologies.

Answer 15

Small scale generation of heat and power.

micro-electric:
Solar PV
wind

Question 16

Renewable energy can be classified as direct or indirect. describe what each of these forms involves and give examples of each.

Answer 16

Direct = the conversion of energy directly from one form to another.
Examples: Wind/Wave/Hydro

Indirect = the use of a physical characteristic of a material being used to obtain renewable energy.
Examples: Solar PV and biomass.

Question 17

Identify the advantages of installing a “close to user” energy generation method, making reference to an equation.

Answer 17

The equation:
P = I (squared) x R
shows that as the length of distance increases for the transmission of power, the less power will actually be able to transmit due to increasing resistance.

Other benefits include:
Reduced energy costs
Enhanced energy security
Financial incentives

Question 18

Define co-efficient of performance

Answer 18

A coefficient of Performance is a measure of the efficiency of a heat pump.

It is the ratio of the energy output from the pump (energy out) to the amount of energy required to operate the pump (energy in).

Question 19

what is the Betz limit?

Answer 19

The Betz limit is the limitation on the amount of energy that can
be extracted from the wind. It was created by a German physicist
known as Albert betz, who calculated that no turbine could
extract more than 59.3% of kinetic energy.

Question 20

explain how a smart grid facilitates the incorporation of electricity generated from renewable sources.

Answer 20

The energy produced from renewable sources varies over time.

A ‘SMART’ grid systems computer measures the amount of electricity that is being produced at any point in time and then increases of decreases the amount of non-renewable that needs to be generated to meet the requirements.

In doing so the ‘SMART grid’ enables the amount of pollutant / carbon dioxide produced to be minimised.

The “SMART” grid system will allow everyone within the grid to become a producer of power that can easily export power to the national grid.

Question 21

Describe and identify the method of how kinetic energy becomes electrical energy using a wind turbine.

Answer 21

The kinetic energy in the wind comes into contact with the rotor blades causing them to rotate. the rotation causes a low speed shaft within the nacelle to rotate which uses a gear box to amplify and increase the speed to a high speed shaft which rotates within a generator. the shaft will be surrounded by magnets, which upon rotation will generate an electric field generating electrical energy.

Question 22

Describe the power conversions and processes within a coal-fired power plant that converts heat energy into electrical energy.

Answer 22

Coal is burned to generate heat. this heat is used to convert water into high pressure steam. this steam is used to rotate turbines, rotating a shaft. the excess steam is brought to a cooling plant to cool and become water again. the rotation of the shaft causes a generator to create an electric field and thus electrical energy.

Question 23

Explain how this factor affects the power output of a turbine and state the proportionality between the power output and this factor: Air density

Answer 23

The air density will determine the force and weight behind the air that will rotate the turbines.
power output = air density

Question 24

Explain how this factor affects the power output of a turbine and state the proportionality between the power output and this factor: wind velocity

Answer 24

The wind velocity is the speed in which the air interacting with the turbines was traveling upon impacting the rotor blades.
power output = velocity (cubed)

Question 25

Explain how this factor affects the power output of a turbine and state the proportionality between the power output and this factor: swept area

Answer 25

The swept area is the area of space covered by the rotor blades that is able to make contact with wind.
power output = radius of the swept area (squared)

Question 26

Describe the purpose of a YAW mechanism within a vertical axis wind turbine.

Answer 26

A YAW mechanism is utilised to rotate a vertical axis turbine into incoming winds. this would maximise the power output of the system and reduce possible damage.

Question 27

How can an automated tracking system maximise the power output of Solar panels.

Answer 27

Solar panels work more efficiently when perpendicular to the sun during the day. by utilising single or double axis systems to rotate the panels, the power output would be far more efficient and produce far more power than other systems.

Question 28

By using scientific terminology, what occurs between the N-type layer and P-type layer of a Solar PV panel, how it generates electricity and what the two layers consist of.

Answer 28

The N-type layer consists of a layer of Silicon that has been doped (contaminated) with an compound consisting of one more electron than silicon does (either phosphorus or arsenic).
The P-type layer is a layer of Silicon created by doping the layer with Boron which has one less electron than silicon.
when these two layers connect they created an area of potential difference known as the depletion zone. this is created when available electrons from the N-type bound with the space with one less electron in the P-type layer.
When light interacts with the PV panel the photoelectric affect occurs, causing a electron to become loose. the area of potential difference will not allow any further electrons into the depletion zone and so will push the electron away. if a cable or connection is made, joining the N-type and P-type layers (Contact grid) then the system will circulate the electron and the circuit will generate power.

Question 29

Name and describe the main forms of Solar PV panels.

Answer 29

Thick-film panels =
Monocrystalline = one crystal to create. take a longer time to create and is more expensive. 25 - 30% efficiency.
Polycrystaline = 20-25% efficiency, cheaper than monocrystallien and can be created quicker.
Thin-film panels = cheaper to purchase, 25-25% efficiency, contains harmful materials,works better at higher tempuratures and functions in low light levels.

Question 30

give examples of forms of passive solar design techniques.

Answer 30

low emissivity glazing
orientation of windows
heavy construction / high thermal mass.
high levels of insulation

Question 31

give examples of forms of concentrating solar design techniques.

Answer 31

parabolic troughs

solar dishes.

Question 32

Define the term Biomass

Answer 32

Biomass is a general term for material derived from plants or animals.

Question 33

identify crops that are commercially grown to produce biomass.

Answer 33

willow
Maize
Sugar cane
Elephant grass (miscanthus)

Question 34

Briefly describe the global debate that surrounds farmers growing crops for energy.

Answer 34

consumption of space.
not as beneficial for all farmers.
global population increase

Question 35

State the typical (%) of energy from combustion that is obtained from biomass.

Answer 35

90%

Question 36

Explain the term: Energy density

Answer 36

Energy density is the amount of energy stored in a given system or region or space per unit volume or mass.

Question 37

State properties which could be compared and contrasted when assessing different types of woodchip for use as biomass fuel.

Answer 37

Moisture content.
Porosity,
Bulk density
Energy density

Question 38

Outline the process of gasification in relation to biomass.

Answer 38

Gasification is a process that converts organic or fossil based carbonaceous materials into carbon monoxide, hydrogen and carbon dioxide.

This is achieved by reacting the material at high temperatures, without combustion, with a controlled amount of oxygen and / or steam to produce syngas.

Question 39

Describe the result of gasification of biomass.

Answer 39

Biomass is converted into a mixture of carbon monoxide and hydrogen
Commonly known as syngas.

Question 40

State applications in which the main product of the gasification of biomass can be utilised.

Answer 40

Used in the production of ammonia.
Used in the production of methanol.
Used as an intermediate in producing synthetic petroleum.
Or can be used as lubricant in chemical processes.
Syngas is combustible and often used as a fuel of internal combustion engines.

Question 41

State one advantage and one advantage of using commercial anaerobic digester.

Answer 41

Answer to include any one of the following advantages;
 Treats waste and reduces greenhouse gases.
 Produces a biogas that can be used as a fuel.
 AD can take place at a location local to where waste or energy crop is produced – therefore reduces the need for transportation.

Answer to include any one of the following disadvantages;
 Requires a steady supply if a consistent feedstock.
 Quality of the gases produced will vary, therefore potentially increasing he need for a gas cleansing process to protect the combustion equipment.
 The process can be slow, particularly during the winter months and may require the addition of extra heat.

Question 42

identify 2 forms of energy storage.

Answer 42

Pumped hydro storage

Compressed air energy storage.

Question 43

Describe the processes of compressed air energy storage.

Answer 43

Energy from a renewable energy resource can be stored during periods of low energy demand (off peak)

Air is compressed by an electrically powered compressor

And stored in mass quantity in an underground cavern

For use in meeting periods of higher (peak load)

When there is a demand the compressed air is released to drive a turbine connected to a generator to produce electricity

Question 44

Identify two pollution problems associated with the use of plastics derived from fossil fuels.

Answer 44

Cannot be broken down by microorganisms.

Incineration produces toxic materials.

Question 45

State 1 application for photodegradable plastic and describe its impact on crops or the environment.

Answer 45

Option 1;
Plastic Mulch

Used as a growth promoter for saplings

In forestry or poor land

Allows soil to be stabilised whilst sapling takes root in otherwise unstable soil.

Option 2;
Coatings for slow release fertiliser / pesticide pellets

Controlled release of active agent

Particularly where risk of leaching

Or where risk of run off is high

Option 3;
Germination enhancing in maize

Where the soil temperature is raised

Above the ambient seasonal temperatures

Thereby speeding up the germination rate

Option 4;
Solarisation

Where plastic over film

Builds up heat

To temperatures harmful to soil pathogens

Question 46

Explain how the additive in the key above can cause a plastic bag to be broken down at the end of its useful life.

Answer 46

Stage 1 – Additive is included in the basic polymer resin during the manufacturing process.

Stage 2 – Breaks the molecular chains so that at the end of its predetermined service life the plastic starts degrading in the presence of oxygen by a process of oxidation, which is accelerated by light, heat and stress

Stage 3 – Bio-degradation is completed by microorganisms.

Question 47

Explain one other option, apart from the use of an additive, that can be used in modern plastic manufacturing processes to improve biodegradability.

Answer 47

Option 1;
Modification of the process to enhance thermal and photodegradation

Addition of different chemical links into long chain molecules of plastic which breaks up when hit by UV light

Option 2;
Production of bioplastics

Addition of starch which is digested by microorganisms – breaks up plastics into smaller pieces

Option 3;
Production of compostable plastics
Made from e.g. corn starch fully biodegradable and compostable