Chapter 7: Energy Resources

Question 1

What is the earths avg temperature?

Answer 1

Earth’s average temperature is 15 degrees which is suitable for all life on the earth.

Question 2

Renewables

Answer 2

It is an energy resource that will be replenshied naturallty when used eg- wind, biofuels, solar.

Question 3

Non renewables

Answer 3

An energy resource that is gone forever once it has been used. Egg fossil fuels, coal, oil and gas.

Question 4

Solar panels

Answer 4

Used to collect energy that is transferred by light from the sun.

Question 5

Solar cell (Other names + definition)

Answer 5

Also called photocell and photovoltaic cell is an electrical device that transfers the energy of dune light directly to electricity by producing a voltage when light falls on it.

Question 6

Biofuel

Answer 6

A material that was recently living that is used as fuel.

Question 7

Fossil fuels

Answer 7

A material formed from a long dead material that is used as fuel.

Question 8

Nuclear fission

Answer 8

It’s the process by which energy is released from a nuclear fuels by splitting the large heavy nucleus into 2 or more smaller nuclei

Question 9

Boiler

Answer 9

A device where thermal energy is transferred to water to turn it into steam.

Question 10

Turbine

Answer 10

A device that is made to turn by moving air, steam or water often used to generate electricity.

Question 11

Generator

Answer 11

A device which generates electricity using electromagnetic induction.

Question 12

Nuclear fusion

Answer 12

The process by which energy is released when 2 small nuclei join together to form anew enavier nucleus.

Question 13

How is sunlight harvested? (3)

Answer 13

1) A device used to collect energy that is tranferered from the sun called solar panels is placed ont he roofs of houses.
2)The sun’s rays shine ona large array of solar cells which is an electrical device that trnasferes the energy of sunlight directly to electricity by producing a voltage when light falls on it.
3) These cells absorb the energy of the rays and electricity is produced.

Question 14

Advantages of solar power (2)

Answer 14

-Solar power is renewable
-Solar power does not contribute to global warming.

Question 15

Disadvantages of solar power (2)

Answer 15

-It is unreliable as the intensity of sunlight varies (and drops at night).
-Requires multiple solar panels in a large area to capture required energy.

Question 16

What is the origin of wind?

Answer 16

As the sun heats some parts of the atmosphere more than others, the heated air expands and starts to move around as a convection current which is the wind.

Question 17

Advantages of wind power

Answer 17

-It is renewable.
-Does not contribute to global warming

Question 18

Disadvantages of wind power (3)

Answer 18

-It is unreliable and is known as a dilute energy resource.
-Wind turbines need a minimum wind speed of 5 m/s and are switched off when the wind speeds up and exceeds over 25 m/s which damages the turbine.
-It takes a wind farm of several 100 wind turbines to spread over several square kilometers to produce the same energy as a typical fossil fuel power station.

Question 19

What is the origin of waves?

Answer 19

Waves are caused by the sun heating [arts of the atmosphere more than others and causing convection currents also known as wind.
Waves are caused by the friction between the wind and the water.

Question 20

Advantages of wave power (2)

Answer 20

-It is renewable
-Does not contribute to global warming.

Question 21

Disadvantages of wave power (3)

Answer 21

-It is unreliable as the height of the wave can vary and waves occurring also depends.
-It is difficult to convert the up and down movements of waves to a spinning motion required for a turbine in water energy convertors that floats on water.
-It is also expensive due to the machines corroding in the salt water and being damaged in storms.

Question 22

How is water harvested for electricity? (2)

Answer 22

-Water stored behind the dam is released to turn the turbine that makes the generator spin.
-In some hydroelectric power stations (called pumped storage systems) the turbines can be reversed so that water can be pumped back up the mountain to the reservoir to be stored as gravitational potential energy.

Question 23

Advantages of hydroelectric power

Answer 23

-These powerplant stations have a very short start-up time (the time between switching on the powerplant and the energy being delivered).
This makes it very useful for storing energy until there is a sudden surge in demand.

Question 24

Examples of biofuels

Answer 24

-Wood is made of trees and shrubs.
-It stores energy that the plant has captured from the sunlight in the process of photosynthesis.
-Animal dung is also an example.
-Biogas is used, it is generated by rotting vegetable matter.

Question 25

Biofuel

Answer 25

A material that was recently living, that is used as fuel.

Question 26

Advantages of Biofuel (2)

Answer 26

-It is renewable and does not contribute to global warming.
-It is reliable because it can be burned when needed.

Question 27

Disadvantages of Hydroelectricity (2)

Answer 27

-If a new reservoir floods the land that might have been used for hunting or farming.
-People may become homeless and habitats may be destroyed.

Question 28

Disadvantages of Biofuel (1)

Answer 28

-Burning biofuels especially indoors can cause a multitude of respiratory or other health problems.

Question 29

What are fossil fuels made of? (2)

Answer 29

-Hydrocarbons are compounds of hydrogen and carbon when they burn they combine with oxygen from the air in this process the carbon becomes carbon dioxide.
-The hydrogen usually becomes dihydrogen monoxide.

Question 30

Fossil Fuels

Answer 30

They are the remains of organisms that lived in the past that is used as fuels.
Oil, gas, coal are all egs of fossil fuels.

Question 31

How is coal made? (3)

Answer 31

-Trees from the carboniferous era captured energy from the sun by photosynthesis and so they grew and eventually died.
-Their trunks fell on the swampy ground and did not rot due to insufficient oxygen.
-The material buildup on the trees caused pressure on them to increase and eventually, multiple years of compression turned them into underground reserves.

Question 32

What 2 fossil fuels are usually found together?

Answer 32

Oil, Gas

Question 33

Disadvantages of fossil fuels (5)

Answer 33

-Burning fossil fuels releases carbon dioxide into the atmosphere, enhancing the greenhouse effect and causing global warming (mostly produced by coal).
-Oil and coal usually produce sulfur dioxide which leads to acid rain and damage to ecosystems and buildings.
-Not renewable.
-Powerplant stations that use fossil fuels take a long time to start up and stop and hence it might take too long to stop when the demand is low causing too much electricity to be supplied and modern battery technology is unable to store large amounts of energy.
-Coal is a less concentrated fuel compared to Uranium.

Question 34

Advantages of Fossil Fuels (4)

Answer 34

-Fossil fuels are a concentrated energy resource and one typical power station can produce the same energy as several hundred wind turbines spread over several square kilometers to produce the same energy as a typical fossil fuels power station.
-Is reliable.
-Can be found very easily (underground).
-Is cost-effective.

Question 35

What are the fuels used as Nuclear Fuels?

Answer 35

-Most of the time it is uranium and sometimes plutonium which are radioactive materials.
-Uranium is a very concentrated store of energy in the form of nuclear energy.

Question 36

Nuclear fission (2)

Answer 36

The process by which energy is released from nuclear fuels by the splitting of a large heavy nucleus into 2 or more nuclei.
The radioactive decay of these materials is sped up so that the release of the stored energy is more quicker.

Question 37

Advantages of Nuclear Fuel (3)

Answer 37

-Nuclear fuel is a relatively cheap, concentrated energy resource.
-Reliable energy resource.
-Emits no greenhouse gases and therefore does not contribute to global warming.

Question 38

Disadvantages of Nuclear fuels (3)

Answer 38

-The initial cost of building power stations and the cost of disposing of radioactive fuel and decommissioning the stations at the end of their working lives.
-It has a huge environmental impact when radioactive materials spread over a wider area like in Cheronobyl in 1986 and Fukushima in 2011.
-Nuclear fuel power stations take a long time to startup and stop. (long start up time)

Question 39

What is geothermal energy?

Answer 39

-The interior of the earth is hot as the rocks present at the shallow depth below the earth’s surface are hot to the presence of radioactive substances inside the earth.

Question 40

How is geothermal energy made use of? (2)

Answer 40

-Water is pumped down into the rocks where it boils.
-High-pressure steam returns to the surface where it can be used to generate electricity.

Question 41

Advantages of Geothermal energy (3)

Answer 41

-Renewable
-Does not contribute to global warming
-Reliable

Question 42

Disadvantages of Geothermal energy (1)

Answer 42

-there are few places on earth where it is available usually found in places where there are active volcanoes.

Question 43

What is tidal energy?

Answer 43

-A tidal power station generates electricity by moving water.

Question 44

How is electricity generated this way?

Answer 44

-A barrage(dam) is built across a river estuary creating a reservoir.
-As the tide goes in and out, water passes through the turbines in the dam.

Question 45

Advantages of tidal energy

Answer 45

-Renewability.
-Tides are fairly predictable making them reliable energy resources.
-Does not contribute to global warming.

Question 46

Disadvantages of tidal energy

Answer 46

-Flooding estuaries may cause tidal power to destroy wetlands are important habitats to wildlife particularly migrating birds that use it to feed and rest before the next leg of their journey.
-The barrage can also block shipping routes.

Question 47

How is ENERGY harvested?

Answer 47

-Thermal energy is produced when fossil fuels burn.
-Nuclear fission takes place to heat the water in the boiler to form steam which turns the blades of the turbine, transferring thermal energy into kinetic energy.
-The turbine is connected to an axel toa generator where a voltage is induced in conducting wires when they move in a magnetic field.
-Hydroelectricity and wind can directly turn the turbine.

Question 48

Examples of energy not taken from the sun (2)

Answer 48

-The moon’s gravitational pull causes the level of the ocean’s surface to rise and fall every 12 and a bit hours.
At high tide, water can be trapped behind the dam.
Later at lower tides, it can be released to drive turbines and generators.
-Nuclear and Geothermal energy relies on radioactive substances found inside the earth.

Question 49

What are the requirements for nuclear fusion?

Answer 49

-It requires very high temperatures and pressure.
-The temperature inside the sun is close to 15 million degrees.
-The pressure is very high so the hydrogen atoms are forced very close together allowing them to fuse.
-At this temperature, all atoms are ionized.
-All electrons have been removed from all the atoms creating a plasma of positive nuclei and negative nuclei.
-Atomic nuclei all have a positive charge and like charges repel so a temperature of about 100 million degrees and high pressure is required to overcome these electrostatic repulsion and get the nuclei close enough to fuse.

Question 50

What is the difference in mass after the fusion?

Answer 50

-The mass of the final nucleus is slightly less than the combined mass of the initial nuclei and the difference in mass is turned into energy according to Einstien’s Law-
E=mc2

Question 51

Disadvantages of nuclear fusion (2)

Answer 51

-Hot plasma must be held in place until fusion can take place.
-The container is shaped like a torus with a complicated arrangement of magnets to stop the plasma from touching the walls.

Question 52

Why is it important for the plasma not to touch the container’s walls?

Answer 52

When it touches the walls it would cool and the fusion would stop and the walls would get damaged.

Question 53

How is energy harvested in the artificial fusion reactor? (5)

Answer 53

-Deutrinium and tritium (2 isotopes of hydrogen) to produce helium and a neutron.
-Only charged particles can experience a magnetic force and can be confined by a magnetic field and so they hit the walls of the tokamak.
-These collisions produce thermal energy.
-Heat exchangers in the walls conduct the thermal energy to help up the water to make steam to turn the turbine and produce electricity,
-No fusion reactor has produced more energy than needs to be put in to keep the plasma hot.