Reliance On Fossil Fuels - From Kindle

Question 1

What is a fossil fuel?

Answer 1

Fuel consisting of the remains of organisms preserved in rocks in the Earth’s crust with high carbon and hydrogen content’.

Question 2

What is renewable energy source?

Answer 2

A renewable energy source is ‘a form of energy derived from natural sources that do not use up natural resources to harm the environment.

Question 3

Briefly outline the formation of coal. State two problems associated with the combustion of coal.

Answer 3

Coal is formed when dead plants fall and accumulate on the ground over time eventually forming peat. Eventually under the ever increasing weight the remains turn into different grades of coal.
It is the most polluting of the three main fossil fuels.
It takes hundreds of millions of years to renew and so is not sustainable.

Question 4

Briefly outline the formation of crude oil and natural gas and state to problems with the combustion of these fossil fuels.

Answer 4

Natural gas and crude oil are formed from the dead remains of sea organisms after settling on the bottom of the oceans and under increasing pressure begin to compress and form crude oil and natural gas.
Harvesting these fossil fuels involves using massive manmade drills which can put the inhabitants of that particular spot in the ocean at risk.
Oil spills can occur when harvesting these fossil fuels which can result in the destruction of much of the habitats underwater.

Question 5

State the three fossil fuels used on Earth.

Answer 5

Coal, crude oil and natural gas.

Question 6

What percentage of the world’s energy demands was met by fossil fuels in the 1960’s? What is this percentage as of 2015?

Answer 6

94% in the 1960’s then dropped to approximately 80% in 2015.

Question 7

List four uses of fossil fuels in modern day life.

Answer 7

Plastic
Pharmaceutics
Transport
Fibres.

Question 8

Suggest a number of ways in which human reliance on plastic can be reduced in the future.

Answer 8

The use of reusable storage containers to replace plastic packaging in shopping centres has proven that progress can be made.

Question 9

Explain briefly why global action is required to tackle fossil fuel depletion

Answer 9

Global action is required as every nation is using fossil fuels. Some nations have taken positive steps to reduce their reliance on fossil fuels and implement a transition towards renewables and low carbon alternative. Global action is also needed because the impact of excessive resource use affects the whole world.

Question 10

Why is conservation of fossil fuels an important issue

Answer 10

Population growth and the continued development of emerging nations, in particular India and China, will continue to increase demand humans have for fossil fuels. This continued rate of fossil fuel usage will result in the more rapid depletion of these resources.

Question 11

Describe the trends in fossil fuel usage since the industrial revolution.

Answer 11

fossil fuels, namely coal, natural gas and crude oil take hundreds of millions of years to form. The rate of usage of fossil fuels has expanded rapidly since the Industrial Revolution.

Question 12

How long are of the three fossil fuels projected to last for? Are these figures accurate? Justify your answer.

Answer 12

Coal is easily projected to last the longest, in the region of 114 years. More alarmingly, natural gas and crude oil are projected to last for a shorter time. Both will effectively be used up in the next 50 years.
This figures may not be that accurate though as there can potentially be many crude oil fields discovered thus increasing the time period until we have used it all up.

Question 13

What role will technology play in determining the lifespan of fossil fuels in the future?

Answer 13

As technology continues to advance, new crude oil fields have the potential to be discovered each year. This initially seems like a good thing and would lead on to naturally expect the duration of the availability of crude oil and natural gas to increase. But the accessibility of each fossil fuel also needs to be considered. A new crude oil Freil might be discovered in the North Sea, but this is not significant if engineering solutions do not currently exist that enable this crude oil field to be drilled and exploited.

Question 14

How does the price of crude oil impact the lifespan of crude oil availability?

Answer 14

When the price of crude oil is high, then businesses such as BP have much more justify investment in new engineering solution to drill to deeper depths. It is evident that higher prices therefore would tend to increase the duration of crude oil and natural gas availability.

Question 15

Name the global scientific panel that publishes data that proves the humans are causing climate change and state its abbreviation

Answer 15

The Intergovernmental Panel on Climate Change (IPCC)

Question 16

State six pieces of evidence provided by the global scientific panel that proves that climate change is caused by humans.

Answer 16

1.More volatile weather patterns have been observed such as increased frequency of flooding events, storms, forest fires (extension of the fire season in the USA) and droughts (leading to crop failures and famine).

2.Sea temperatures have risen.

3.Ecological changes such as the damaging of the coral reefs off the coast of Australia.

4.Polar ice caps are melting.

5.Rises in sea levels (75% of which is due to the thermal expansion of water particles and 25% due to the polar ice caps melting).

6.Levels of carbon dioxide in the atmosphere have increased significantly.
7. Increased hurricane activity
8. Fewer cold days, nights and frost events
9. Hot days, nights and heat waves are more common.

Question 17

What is carbon trading?

Answer 17

Carbon trading is a method that aims to reduce carbon emissions of a nation, by providing incentives for major polluting industries

Question 18

Outline the aims of carbon trading and how the process works

Answer 18

Carbon trading is a method that aims to reduce carbon emissions of a nation, by providing incentives for major polluting industries. A nation is provided with a certain number of carbon permits based on its national target levels set by the Kyoto Protocol. This international agreement which took place in 1997 in Japan came into effect in 2005. It committed natin to reducing their carbon emissions. The European Union (EU) has a carbon trading scheme called the Emissions Trading Scheme (ETS), it is mandatory for all EU members. Under the EU ETS, each member states passes a portion of the permits granted under the Kyoto Protocol to its major polluting industries. A permit in the existing carbon trading scheme is considered equivalent to on tonne of carbon dioxide.

Question 19

State four advantages of carbon trading.

Answer 19

Environment - reduce Co2 emissions
Control - control over Co2 emissions by a government
Financial Incentive - provides governments and large industries financial incentives to use the scheme
Flexibility - allows a period of transition

Question 20

State four disadvantages of carbon trading.

Answer 20

Complexity of the market

Economy

Size of permits

Difficulties surrounding the measuring of emissions

Question 21

Carbon trading is a policy used to alter greenhouse gas emissions.

explain what is meant by carbon trading and outline three aspects of how it works in practice

Answer 21

*A carbon trade is an exchange of carbon credits between countries.
*Countries are assigned max level carbon emission levels.
*If a country exceeds its max level it is penalised.
*Countries that have higher carbon emissions can buy the right to release more CO2 into the atomsphre from countries that have lower carbon emissions.

Question 22

State one reason why carbon trading policy may not alter greenhouse gas emissions

Answer 22

There are difficulties in governing the carbon trading scheme. As a result, markets are open to fraud and manipulation (investors priorities buying and trading permits to make money, not help the environment.

Question 23

Name nine different forms of energy and give a description and example of each.

Answer 23

Kinetic; a person walking
Thermal; a hot cup of coffee or tea
Gravitational potential; an apple on a tree that might fall
Chemical; food, batteries, such as petrol and diesel
Sound; sound waves in the air or water
Electrical; electricity in a home or on a phone
Elastic potential; a stretched elastic band
Nuclear; nuclear fission r fusion
Radiant; energy to heat the earth and solar PV and thermal cells.

Question 24

Describe what the thinness of the arrows in a Sankey diagram represent

Answer 24

The width of the arrows represents the law of the conservation of energy

Question 25

What exactly does heat mean and how does it differ from thermal energy

Answer 25

Heat is the process of energy being transferred from one point to another due to the difference in temperature between them. Every single body possesses thermal energy, but heating occurs when this energy is conveys away (cooling) or towards (heating up) the body.

Question 26

What is the definition of the law of conservation of energy?

Answer 26

Total Energy in = Total Energy out or E in = E out

Question 27

State the law of observation of energy.

Answer 27

Total energy in should be equal to the total energy out.

Question 28

Which type of fossil fuel, as of 2019, does the UK currently rely on heavily?

Answer 28

As of 2019 the UK relies heavily on Crude Oil.

Question 29

Which fossil fuel does to UK intend to phase out by 2025? Why is this the case?

Answer 29

The UK intends to phase out coal by 2025. This is because it is the most heavily pollutant of all three fossil fuels.

Question 30

State and describe the four stages in the production of electricity in a fossil fuels power plant.

Answer 30

Stage 1. Combustion of the Fossil Fuel / The fossil fuel is combusted in a furnace, as per figure 5.1, to release the chemical energy that it contains. This combustion specifically releases thermal energy. Stage 2. Evaporation of Water/ The thermal produced by the combustion of the fossil fuel is then used increase the temperature of the water in the furnace. Water enters the furnace in liquid form. The temperature of the water in the furnace is very high and increases the temperature of the much cooler water as energy is transferred to the water. The temperature of the water increases considerably, and it evaporates at 100*C into steam. This steam is ejected from the furnace and directed into the steam turbine. Stage 3. Steam Used to Turn a Turbine/ This steam turbine turns when the high-pressure steam is forced through it. Steam, which is extremely high velocity water molecules, collides with the fins of the steam turbine causing the turbine to turn. But the steam molecules have less energy after each collision. Hence the steam which is entering the steam turbine at its hottest temperature, leaves at a lower temperature, but is still hot. The hot steam is now sent to the cooling towers. Stage 4. Condensing in The Cooling Towers/ The hot steam from the steam turbine Exeter’s the cooling towers which can be viewed in Figure 5.2. Here the steam loses substantial energy so that the steam condenses back into water (liquid). Then the liquid which is cold as per figure 5.1 is recirculated back to the furnace and process is repeated.

Question 31

indicate any disadvantage associated with the cooling towers as used in traditional power plants.

Answer 31

The cooling towers take considerable energy from the steam and eject it into the atmosphere. Clearly this will tend to reduce the efficiency of a power plant considerably.

Question 32

State typical efficiencies of conventional fossil fuel power plants.

Answer 32

Depending on the specific thermodynamic cycle implemented by the power station the efficiencies will fluctuate slightly above or below 40%. A relatively new method, Combine Heat and Power (CHP), aims to capture this energy lost in the cooling towers. It is used to heat buildings near the power plant.

Question 33

State the definition of a direct renewable energy source.

Answer 33

These renewable energies take energy from a renewable sources such as the wind or waves in the ocean and can convert this into electrical energy directly.

Question 34

State the exact four example of direct renewable energy sources specified by CCEA.

Answer 34

Wind, hydroelectric, wave and tidal energy.

Question 35

State the definition of an indirect renewable energy sources specified by CCEA.

Answer 35

These take energy from a renewable source such as the sun using a physical characteristic of the material being used, and convert this energy into electrical energy.

Question 36

State the two examples of indirect renewable energy sources specified by CCEA.

Answer 36

Solar PV and Biomass

Question 37

Renewable energy sources can be used to generate electricity either directly or indirectly. Give one example of their use to generate electricity directly and one example of their use to generate electricity indirectly.

Answer 37

renewable energies take energy from a renewable sources such as the wind or waves in the ocean and can convert this into electrical energy directly. These take energy from a renewable source such as the sun using a physical characteristic of the material being used, and convert this energy into electrical energy’. Examples include solar PV and Biomass.

Question 38

Identify the main energy transformation that take place in a wind turbine.

Answer 38

Wind energy enters the turbine and is then converted into kinetic energy to push the plane along.

Question 39

Describe the traditional means by which electricity has been supplied across the National Grid.

Answer 39

Over the past number of decades electricity was distributed from a small number of producers, power plants run from various different fuels, to the end consumer of which there are many. This involved the flow of electricity in one direction; this was from the power plant to the end user.  An illustration of the conventional means of distributing electricity on the National Grid

Question 40

Outline how a SMART grid works.

Answer 40

A SMART grid is needed to incorporate renewable sources of electricity and plan and manage the intermittent nature of these energy sources. 

Question 41

What are the benefits of a SMART grid

Answer 41

A SMART grid maximises the proportion of renewables providing electricity for a nation.

Question 42

Explain how a SMART grid facilitates the incorporation of electricity generated from renewable sources.

Answer 42

The SMART gird will have a network of intelligent meters located throughout the National Grid to accurately predict demand.

Question 43

Explain the concept of a SMART grid.

Answer 43

A computer-controlled electricity network that switches input from one energy source to another as demand for energy varies on the gird.

Question 44

What is an interconnector

Answer 44

An interconnector is simply an electrical cable joining two nations together

Question 45

Identify and describe the chareateristics of two interconnectors that exist between the Irish SEM grid and GB

Answer 45

The electricity markets of NI and the ROI joined what is known as the SEM which became operational in 2007. This all-island grid aims to provide electricity at least cost, incorporation the maximum proportion of renewables.

Question 46

State the economic benefits of a SMART grid with nations in Europe interconnected.

Answer 46

With more competition for business, this will drive down costs for consumers. A nation’s and a region’s fuel security is increased greatly, and the EU member states will be less reliant on volatile fossil fuel prices in the years ahead.

Question 47

What does CHP stand for

Answer 47

Combine Heat Power

Question 48

State another name for CHP

Answer 48

Co-generation

Question 49

State the disadvantages of traditional power plants and their type all efficiencies

Answer 49

Excess power is lost in the form of steam in the cooling towers, they normally have a power efficiency of 44%

Question 50

How do CHP plants differ from traditional plants

Answer 50

They make use of thermal energy given off by the steam which would have been otherwise lost in the cooling towers

Question 51

State four advantages of CHP power plants.

Answer 51

1. The efficiency of the overall process can exceed 80% 2. The CHP plant is typically located close to the end user and so transmission losses are reduced 3. Carbon emissions are reduced as less fuel is required 4. Energy bill can be minimised for consumer

Question 52

State the definition of microgeneration

Answer 52

The small scale generation of heat and power

Question 53

What is meant by the term microelectricty technologies

Answer 53

Microelectricty technologies refers specifically to small devices that are capable of producing electricity.

Question 54

State two examples of of microelectricty technologies

Answer 54

Solar PV and Wind

Question 55

What is meant by microheat technologies

Answer 55

Microheat technologies refer specifically to small devices that are capable of producing heat.

Question 56

State three examples of microheat technologies

Answer 56

Solar Thermal, ground source heat pump and biomass

Question 57

Identify two of the main benefits of home or community microgeneration of electricity.

Answer 57

1. They require less heat from the national grid 2. They require less heating oil

Question 58

List 3 differences between a HAWT and a VAWT

Answer 58

HAWT required a relatively consistent wind direction, high speed, high RPM, High vibrations, High noise levels and a Horizontal rotor axis plane.

Question 59

Why can 100% of the wind’s energy never be extracted from a wind turbine

Answer 59

The upper limit of energy that can be extracted from the wind is 16/27 or 59.3%. Even this number is not reachable in many circumstances due to the loss of energy in the movement of the components of a turbine

Question 60

Can a turbine every really extract the Betz limit (59.3%), justify your answer.

Answer 60

This theoretical limit can never actually be achieved due to energy losses in the wind turbine system.

Question 61

Explain the relationship between the power output and swept area of a HAWT

Answer 61

Power output is directly proportional to the swept area

Question 62

State another term for human induced

Answer 62

Anthropogenic

Question 63

What does altitude mean? Where is it measured from?

Answer 63

Altitude is how high a specific point is above the surface of the Earth. Most often sea level is used as the datum point on the Earth’s surface.

Question 64

Describe air density at low altitude. What happens to P out at low altitude?

Answer 64

Higher altitude means lower air density. This means that aeroplanes fly at high altitude because the air is thicker at lower altitudes and therefore there is increased drag forces as the plane moves through the air. This in turn decreases P out.

Question 65

State and describe eight parameters that affect the maximum energy production of a wind turbine.

Answer 65

1. Wind speed: wind speed is the most critical parameter as power output is directly proportional to v^3. Accurate wind speeds for the specific site location are required to establish if the project will be viable. 2. Air density: Air density is directly proportional to power output; however, its value will only change by approximately 10% from winter to summer time. As such its relatively constant value mean that it is not a critical consideration when undertaking the CBA. 3. COP: It has been established that some highly efficient wind turbines have a COP of up to 0.45, with those of poor design only reaching a COP of 0.2. This will have a huge impact on the maximum energy that can be generated by the wind turbine and careful selection of the turbine is required. 4. Swept area: The power output is directly proportional to the swept area. While this would suggest that installing a larger turbine is thereby desirable. 5. Obstructions: The proximity of the site to nearby obstructions such as hedgerow, trees and buildings could have a devastating impact Joni maximum energy production. 6. Hub hight: Wind speeds tend to be lower near the ground and increase with height above the ground. It is for this reason that turbines area placed on tall towers. 7. Temperature: Variations in temperature will cause a very small change in air density and as such are not a critical consideration in terms of maximum energy produced on the site. 8. Altitude: For sites that are located at significant altitudes the changes to air density must be considered as they have a significant impact on the maximum energy that can be production.

Question 66

State the equation used to preform a cost benefit analysis (CBA) for a project.

Answer 66

Repayment period in years = Project costs / revenue produced per year.

Question 67

Outline what a wind resource assessment is and how it is used in determining the hub height.

Answer 67

It is possible to undertake a desktop study in the internet to get an estimate of the average wind speed at the site location. The benefit of completing this desktop study is the low cost involved. But there are limitations. The websites specify average wind speed on a per square km grid, and as such do not take into consideration topography and any nearby obstructions which will impact on air flow through the proposed site location.

Question 68

Why must a wind resource assessment be carried out to make a project economically feasible?

Answer 68

If a manufacture offers a tower at 25m and 35m for example, the data gathered from the wind resource assessment will indicate if there are considerable differences between the wind speed at 25m and 35m. If there is little difference, the investment in the larger 35m tower will not be feasible.

Question 69

State and describe three other parameters, apart from wind resource assessment, used in determining the hub height required for a wind turbine project.

Answer 69

1. Terrain: The topography of the ground around the turbine may be beneficial or a constraint for the turbine project. 2. Wind Turbine Size: It is obvious and logical that the larger the wind turbine, the larger a tower will be. 3. Visual Impact: Some planners may object to larger hub heights on the basis that wind turbines have an adverse visual impact.

Question 70

Although there is no set equation linking rotor diameter and hub height, state the general relationship between them.

Answer 70

Hub heights tend to be approximately 1 to 1.4 time the rotor diameter.

Question 71

Outline 2 critical factors that must be taken into account when determining the hub height for a wind turbine installation.

Answer 71

Terrain: The topography of the ground around the turbine may be beneficial or a constraint for the turbine project. Wind Turbine size: It is obvious and logical that the larger the wind turbine, the larger the tower will be. The larger the winds power rating the larger the hub height will have to be.

Question 72

Describe two ways in which the performance of a wind turbine could be influenced by the following factors: 1. Blade length. 2. Strength of materials. 3. Sitting requirements.

Answer 72

1. Blade length: Pout is directly proportional to the square of blade length. From this relationship the obvious effect of an increase in blade length is an increase in the power output. 2. Strength of material: There are obvious advantages in making the materials as lightweight as possible which will reduce transportation costs and lower the cut in speeds of a turbine. 3. Siting requirements: The topography of the ground surrounding the proposed location, has an influence on the performance of the wind turbine.

Question 73

Explain what is meant by the terms cut in and cut out speed.

Answer 73

Cut in speed: This is the minimum wind speed required to overcome the inertia of the static wind turbine. Cut out speed: This is the maximum speed a wind turbine will rotate before shutting off due to the turbine becoming unstable.

Question 74

State the definition for wind survival speed.

Answer 74

The maximum wind speed that a turbine is designed to withstand before sustaining damage.

Question 75

Why is it critical that manufacturers are aware of the wind survival speed, and what critical parameter does it determine?

Answer 75

When the rotor spins too quickly, the forces and stresses experienced by the blades and tower may become too large and the rotor may fail. This can cause the wind turbine to break apart and if a piece of the turbine were to land on someone this could prove fatal.

Question 76

Describe the testing method that can be used to establish the wind survival speed.

Answer 76

Destructive testing: Here the product will be tested under extreme conditions until it fails.

Question 77

What name is given to the method of rotating the blades of a turbine?

Answer 77

Pitching

Question 78

Why are the blades rotated?

Answer 78

To control the rate of power production.

Question 79

Outline the benefits of being able to rotate the blades of a turbine to control the power production of a wind turbine.

Answer 79

If the wind speeds become dangerously large, the cut-out speed is reached. At this point the turbine needs to ceases rotation. The blades are able to rotate in order to prevent further rotation and could potentially save lives.

Question 80

Wind turbines are designed with a range of power control systems. Name one power control system used in wind turbines.

Answer 80

Pitching.

Question 81

In your own words describe what yawing involves.

Answer 81

Yawing involves turning the nacelle of the wind turbine upward, and so causing less collisions of air particles with the turbines.

Question 82

Outline how passive yawing operates. Stage the advantages and disadvantages.

Answer 82

Small scale turbines utilise a wind vane at the back which aligns with the wind direction. This design offers benefits in terms of cost and simplicity, requiring no electronics, motor or hydraulics that may fail and need maintenance annually.

Question 83

Outline how active yawing operates. State its advantages and disadvantages.

Answer 83

A more complex solution is required to produce the huge forces needed to turn the nacelle to ensure that the swept area is always facing into the wind. The control unit is located at the back of the nacelle. This will include a anemometer which measure the wind speed.

Question 84

A student suggest utilising yawing to rotate the nacelle so that power production stops when the cut-out speed is reached. Is this a sensible suggestion? Justify your answer.

Answer 84

This is not a sensible solution due to the fact that when the cut out speed is reached the turbine will already be rotating dangerously fast and there will be a risk that it will already be malfunctioning and falling to pieces.

Question 85

Describe the purpose of the yaw system

Answer 85

The purpose of the yaw system is to control the output of energy from a wind turbine.

Question 86

Discuss issues that are critical in determining the energy output from a proposed wind turbine project.

Answer 86

1. The turbine selected: Key features that affect the energy output include its COP, blade length, swept area and materials the blades are made from. 2. Topography: Topography of the local terrain and the possibility of obstruction which may cause turbulent air flow. 3. Orientation of the site: Is the turbine situated to take advantage of prevailing winds? Available wind speed: A wind resource assessment would be critical as power output is directly proportional to the cube of V. The positioning of the site in relation to altitude and thus air density as power output is directly proportional to air density

Question 87

Discuss the costs that are involved in the planning, installation and running of a wind turbine project.

Answer 87

Installation costs: These will be more expensive out at sea and in mountainous areas where an access road and turning circle are required and may need to be installed. The turbine cannot be installed until these are adequate. Grid connection costs: The cost to connect the National Grid depends upon how far the wind turbine is from the nearest feasible transformer. With approximate costs of £65,000 per km these costs could make a project unfeasible. Servicing: The turbine can cost thousands of pound per year. End of life costs: The owner is responsible for decommission g at the end of the wind turbines derive life and either disposing of it or transporting it for refurbishment for use elsewhere. Surveys: Potential surveys include those for noise, shadow flicker and the effect on wildlife including bats. Each survey may cost several hundred pounds and the planning application itself will cost hundreds of pounds.

Question 88

Discuss the environmental and social issues that must be considered when assessing the validity of a wind turbine proposal.

Answer 88

Visual issues: Planners and local residents can reject the planning application on grounds of the ‘visuals impact’. Noise pollution: There are general guidelines in relation to how close a turbine can be to nearly houses by the council may require a noise assessment to demonstrate no adverse issues within close proximity to the turbine. Communication links: The swept area may be located in a zone where links between public infrastructure exist. Such example might be local waste water treatment works sending operational information from pumps back to their headquarters. The turbine might affect these communication if placed in these zones. Environmental impact assessment: This may be required to ensure tat the access road and turning circle are adequate and fit for purpose. It may also require surveys to be completed to prevent habitat destruction, for example, a bat survey. Local objections: The planning application is put to public notice and members of the local population may object.

Question 89

What is the term given to active solar heating?

Answer 89

Domestic Hot Water (DHW)

Question 90

State whether solar thermal panels installed in NI are passive or active and describe why this must be the case.

Answer 90

In NI the systems are active and require the use of a pump.

Question 91

What are the three key components of all solar thermal systems?

Answer 91

1. A solar collector. 2. An energy transfer system (via a heat transfer fluid). 3. Storage tank.

Question 92

Describe briefly the operation of a thermosiphon solar thermal system, and identify their advantages and disadvantages.

Answer 92

The uptake of these restrictions was restricted to warmer states in the USA that could provide the consistent high solar radiation levels required too produce the natural convection currents to circulate the heat transfer fluid.

Question 93

Do solar thermal systems in NI have direct or indirect loop systems? Explain why this type is preferred in NI and outline the basics of its operation .

Answer 93

In NI indirect loop systems are used. This is due to the fact that there would not be enough heat given off by the sun to directly heat the water

Question 94

What is the purpose of a solar collector?

Answer 94

A solar collector captures energy from the sun and transfers this to a heat transfer fluid.

Question 95

How does a solar thermal panel digger from a solar PV panel?

Answer 95

A solar PV system is one where the light hits a solar panel and is turned into electricity. On the other hand, a Solar Thermal System absorbs sunlight and uses the energy to heat your office or water.

Question 96

Identify unique locations where solar PV systems are particularly suitable.

Answer 96

1. Remote homes where connection to the grid may not be possible or expensive. 2. Communications satellites in space. 3. Communications and remote monitoring of infrastructure on Earth (Such as Waste Water Treatment Works).

Question 97

What was the first notable application of solar PV technology?

Answer 97

It was not until researchers in Bell laboratories in the 1950’s developed cells from silicon which had efficiencies of some 6% that interest started to develop in solar PV technology.

Question 98

What major event in the 1970’s triggered a huge increase in the interest of solar technology.

Answer 98

The oil crisis of the 1970’s is what caused a huge increase in the interest in solar technologies.

Question 99

Why has the rate of installation of solar PV systems in NI declined significantly since 2017?

Answer 99

The ROC’s were reduced to three, then two which caused a reduction in the revenue for exported electricity onto the grid. Eventually there was no financial stimulus provided upon the closure of the Northern Ireland Renewables Obligation scheme on the 31st March 2017.

Question 100

Solar radiation arrives on the surface of a solar collector by three different methods. Name these three different methods and describe each in detail.

Answer 100

Direct radiation: This method, as the name implies, involves sunlight that travels from the sun in a straight line directly to the surface of the Earth. Because the rays travel in a straight line, and parallel to each other, they can be blocked by an object and thus can create shadows. Diffuse radiation: All light striking the Earth’s surface cannot be accounted for by direct radiation. As sunlight strikes the Earth’s atmosphere some of it is scattered in different directions as it interacts with the molecules in the atmosphere. Reflected radiation: This radiation strikes a surface on the earths surface and is reflected. This reflected light can then go on to strike another part of the Earth, building or even a solar panel.

Question 101

Would a Solar tracking system, either single or dual axis, be a viable business investment in NI? Justify your answer.

Answer 101

No, this is due to the fact that Northern Ireland simply does not get enough solar light from the sun to be able to power these solar tracking systems.

Question 102

What is the ideal orientation of a solar collector placed in the Northern Hemisphere? Is this the same in the Southern Hemisphere?

Answer 102

The optimum pitch for a collector in Ireland and the UK is approximately in the range of 35* to 40*.

Question 103

What are the generally accepted tolerances in terms of degrees either side from the ideal location in a given hemisphere?

Answer 103

0* - 45* North or south

Question 104

How does a dual axis tracking system differ from the single axis tracking system?

Answer 104

The dual axis tracking system has an additional degree of rotation, the additional axis of rotation lies in the east, west plane.

Question 105

What additional benefits are offered by a dual axis system compared to a single axis tracking system?

Answer 105

1. The energy output from the system will be much higher than a fixed system by as much as 35%. 2. With outputs much higher the repayment periods are reduced which makes them better long-term investments in warmer climates.

Question 106

Describe he basic operation of the flat plate collector.

Answer 106

Clod water is pumped into the collector at low level. Here it enters and travels up hear absorbing riser tubes. Water enters at low level and rises up the collector to correlate with natural convection currents which also rise upwards. The beast absorbing riser tube are connected to an absorber plate, sometimes on top of it, sometimes under it. It has a special black paint applied which maximise the system’s absorption of solar radiation. Under this absorber plate is insulation which reduces the heat losses from the system through conduction and convection.

Question 107

State the advantages of the flat plate collector.

Answer 107

1. It is the cheapest collector availed which is this main benefit. 2. It is suited to colder environment where snowfall is likely. This is because the snow can be melted due to conduction and convection heat losses from the panel. 3. The efficiency of converting solar energy into thermal energy is good at approximately 80%.

Question 108

State the disadvantages of the flat plate collector.

Answer 108

1. Even with the use of insulation to minimise the heat loses, they do exist, through conduction and convection within the flat plate collector. 2. In higher temperatures the collector efficiency drops considerably especially over 30*C. 3. Installation requires at least two people. 4. As the collector surface is flat it will only be facing the Sun directly once per day. 5. The weight of the panel filled with the heat transfer fluid can impose considerable loads on the roof surface and structure.

Question 109

Describe five parameters that influence the area of solar collectors required for a solar thermal system.

Answer 109

1. Solar radiation levels: A location near the equator has very high solar radiation values and thus would require a smaller sized solar collector areas to meet a family’s needs. 2. Shading: If the proposed solar collector site has sunlight blocked at certain times of the day or year, by obstructions such as trees or buildings, then a larger solar collector area is clearly required. Collector type: The type of collector will offer different efficiencies. The flat plate collector can operate at 80% efficiency, while an Eva turned tube can operate at 90% efficiency. Family size: It is logical that a larger family will require more hot water on a daily basis. Therefore, a larger family will require a larger solar collector area compared to a smaller family. Lifestyle of users: The daily habits and lifestyle choices of people will also have an impact on the quality of hot water used by a household.

Question 110

State one benefit to households of installing a flat plate collector.

Answer 110

While it is less efficient, it costs less.

Question 111

Explain the main benefit of installing a flat plate solar collector

Answer 111

While it is less efficient, it costs less.

Question 112

State one problem associated with generating electricity from ocean waves.

Answer 112

Clearly wind turbines and solar systems cannot be considered reliable as there is no consistency in their performance.

Question 113

Renewable energy sources have the potential to deliver a significant proportion of our energy needs in the future. State one main reason why energy storage facilities are needed in order for us to make optimum use of renewable energy sources such as wind, solar and tidal.

Answer 113

During certain times there may be a lack of wind or sunlight, which would result in some of these being deemed useless. This means that there will need to be a way of storing energy produced so there will be reserves if they are needed.

Question 114

There are significant wind available in and around Northern Ireland. State one main reason why we need good energy storage facilities if we are to make optimum use of available wind energy resources.

Answer 114

Wind energy offers the opportunity to produce energy at night but demand during these periods is low. This will likely change in the future with the increased electrification of cars. The capacity to store this energy will increase the effectiveness of the renewable energy systems such as solar and wind through.

Question 115

State three factors that would make a potential location both beneficial as well as costs effective for the type of energy storage facility shown below.

Answer 115

1. The availability of existing lakes and reservoirs. 2. Suitable topography through an adequate height difference (head) between the lower and upper reservoir. 3. The proximity of the site to a high voltage power transmission network. As the distance increases, it will cost much more many to connect to the national gird.

Question 116

State two factors that would make a potential location beneficial as well as cost effective for the type of energy storage facility shown in the figure below.

Answer 116

1. The availability of an existing cavern underground. Constructing one would make such a project too expensive and therefore make the project unfeasible. 2. The proximity of the cavern to a high voltage power transmission network. As the distance increases, it will costs much more money to connect to the National Grid.

Question 117

Name another type of energy storage facility.

Answer 117

Pumped hydro