Physics- Energy Resources

Question 1

Guve 5 examples of renewable energy resources

Answer 1

• Hydroelectric
• Wind
• Tidal
• Wave
• Solar
• Geothermal

Question 2

Give four examples of non-renewable energy resources

Answer 2

• Coal
• Oil
• Natural gas
• Nuclear

Question 3

How does a fossil fuel burning power station work?

Answer 3

A fuel burns to heat water and produce steam. The steam drives a turbine, which is a bit like a big fan. The turbine drives a generator to create electricity.

Question 4

How does a nuclear power station work?

Answer 4

Nuclear fission occurs as atoms are shot at eachother at extreme speeds, creating a chain reaction, resulting in lots of heat. This heat heats water which produces steam as it evaporates. The steam drives a turbine and the turbine drives a generator to create electricity.

Question 5

Why are biofuels carbin neutral?

Answer 5

They are carbon-neutral which means that the carbon released when biofuels are burnt is the balanced by the
carbon they absorbed as they grew.

Question 6

Why aren’t fossil fuels carbon neutral?

Answer 6

Because when they are burnt to produce energy through heat, they release more carbon dioxide into the atmosphere than was orignially there as fossil fuels don’t absorb carbon dioxide like biofuels do.

Question 7

What are the problems associated with biofuels and their production?

Answer 7

• We can’t make enough by diesel to replace regular diesel because there are not enough vegetable oil crops.
• Biodiesel can also be made from used fish oil but there isn’t enough of that either.
• Bio diesel is expensive.

Question 8

Why are wind turbines, wave generators, hydroelectric systems, and tidal systems renewable energy resources?

Answer 8

Because the resources used to create the energy through these systems and generators will never run out within a human lifetime.

Question 9

How does wind energy work?

Answer 9

As wind pushes the blades of the wind turbine around a rotor which spins a generator, creating electricity.

Question 10

compare the operation of hydroelectric, wave, and tidal systems in terms of reliability, potential power

Answer 10

Hydroelectic energy is reliable as there is a constant renewable source of energy. Furthermore, energy can be stored, the water cam be re-used and it meets energy demans quickly. On the other hand, wave and tidal systems are much less reliable as it isn’t constantly wavy and the tide only changes approximately twice a day, limiting the amount of energy produced. Furthermore, tidal energy only produces substantial energy when the tide differs at least 5m in height. However, wave systems have a lot of potential power if it were to be extremelly windy, causing large waves, producing lots of energy.

Question 11

What are the advantages of renewable energy?

Answer 11

• Doesn’t have any carbon emmisions or negative effect on the environment
• Difersifying energy supply
• Reduces dependance on fossil fuels and nuclear power
• Often lower energy costs

Question 12

What are the disadvantages of renewable energy?

Answer 12

• Often unreliable
• Expensive set up cost
• Often produces far less energy than non-renewable energy sources
• Doesn’t produce enough energy for society to mainly rely on

Question 13

How does the hydroelectic system opperate and produce energy?

Answer 13

Before water, from the resevoir above the dam, flows down, it has potential energy. As it flows down it spins on turbine. As a result, it drives generator which produces electricity. The water can then be re-used again to create electricity.

Question 14

What is the purpose, operation, and advantages of a pumped storage system?

Answer 14

Pumped-storage hydroelectricity allows energy from intermittent sources (such as solar, wind) and other renewables, or excess electricity from continuous base-load sources (such as coal or nuclear) to be saved for periods of higher demand. When there is excess power on the grid and demand for electricity is low, the power is used to pump water from the lower to the upper reservoir using reversible turbines. This can be useful as it means for when demand increases suddenly, the energy demands can be met quickly without a long start-up time. This can also be useful as it allows the resources to be re-used to create further electricity.

Question 15

What energy resource has the quickest start-up time?

Answer 15

Natural gas power station

Question 16

How much energy is released per kg of fuel between a fossil fuel power station and nuclear power station?

Answer 16

• Fossil fuel power station: 30MJ
• Nuclear power station: 300,000 MJ

Question 17

How does a solar cell operate?

Answer 17

When the semiconductor is exposed to light, it absorbs the light’s energy and transfers it to negatively charged particles in the material called electrons. This extra energy allows the electrons to flow through the material as an electrical current.

Question 18

Compare and contrast the operation of solar cells (photovoltaic cells) with solar heating panels.

Answer 18

Solar cells (photovoltaic cells) systems convert sunlight directly into electricity, using the extra electricity towards electrons to create an electrical current, whilst thermal systems produce thermal energy for residential heating systems such as hot water or space heaters, using solar energy to heat a fluid (either liquid or air).

Question 19

What are the power outputs of different energy sources?

Answer 19

• Wind: Very low
• Hydroelectricity: Medium
• Geothermal: Medium
• Tidal: Potentially very high, but unreliable

Question 20

What are the differences between solar cells and solar heating systems?

Answer 20

Solar heating systems are used to collect sunlight and and use the solar energy to heat a fluid (either liquid or air) and produce thermal energy for residential heating systems such as hot water or space heaters. Solar panels, on the other hand, utilise PV technology to capture sun rays and directly convert the sunlight into electricity.

Question 21

How does a solar power tower work?

Answer 21

The setup includes an array of large, sun-tracking mirrors known as heliostats that focus sunlight on a receiver at the top of a tower. In this receiver, a fluid is heated and used to generate steam. This steam then powers a turbine generator to generate electricity.

Question 22

How do you calculate the energy provided by a solar heating system by using the increase in water temperature?

Answer 22

Energy = rate of flow (in kilograms/s , kg/s) x Specific heat capacity of water x Change in temperature of the water (°C)

Question 23

Why is radioactive decay the source of heating in geothermal systems?

Answer 23

Certain elements, known as radioactive elements such as potassium, uranium, and thorium, break down through a process known as radioactive decay, and release energy as heat. Heat from the core is constantly radiating outward and warming rocks, water, gas, and other geological material, which become the source of heating in geothermal stystems

Question 24

How does a geothermal power plant work?

Answer 24

Geothermal power plants use steam to produce electricity. Hot watee is pumped from resevoirs underground through a well under high pressure. When the water reaches the surface, the pressure is dropped and it turns to steam. The steam rotates a turbine that activates a generator, which produces electricity. The hot water can also be directly circulated into homes for heating and hot water.

Question 25

What are the factors that affect the power output of a solar cell?

Answer 25

• Load resistance
• Sunlight intensity
• Shading
• Cell temperature
• Tilt
• Climate
• Latitude

Question 26

What are some environmental problems associated with fossil fuels?

Answer 26

• Greenhouse gasses
• Climate change
• Acid rain
• Damage to crops and forests
• Air pollution
• Water pollution (oil spills)

Question 27

What are the effects of acid rain and climate change?

Answer 27

• Acid rain- acid rain has detrimental effects on trees, through dissolving important nutrients for the tree’s growth, freshwaters and soils, destroys insects and aquatic life-forms, causes paint to peel, corrosion of steel structures such as bridges, and weathering of stone buildings and sculptures, as well as impacts on human health.
• Climate change- Climate impacts are already harming health, through air pollution, disease, extreme weather events, forced displacement, pressures on mental health, increased hunger, extreme weather, natural disasters, hitter temperaturs and poor nutrition in places where people cannot grow or find sufficient food.

Question 28

What are methods of reducing damage caused by waste products of fossil fuels and nuclear fuels?

Answer 28

Placing packaged radioactive waste in an engineered, underground facility or ‘repository’. The geology (rock structure) provides a barrier against the escape of radioactivity. Methods of reducing damage caused by waste products of fossil fuels is relying more on renewable energy sources instead of fossil fuels to prevent the negative affects of fossil fuels from further damaging the environment.

Question 29

What are the waste products of fossil fuels and nuclear fuel?

Answer 29

• Radioactive waste and material
• Oil spills
• Harmful gasses
• Acid rain
• Air and water pollution

Question 30

What are techniques to reduce the harmful products of burning fossil fuels?

Answer 30

• Carbon capture- Filters the polluting gasses at the factory to prevent air pollution
• Use more renewable energy sources- carbon neutral energy resources such as biofuels
• Monitor air quality warnings and take action on areas with poor air quality
• Conserve energy and reduce energy demands

Question 31

What are the problems associated with nuclear accidents?

Answer 31

• Higher risks of cancer
• Risk to public health- deaths and mutation to newborn babies
• Affects growth of crops and safety to eat
• Radiation affects the soil and therefore the growth of plants
• Innitial explosion acts as a threat to human and animal life
• Surrounding areas nust be evacuated; people lose their homes
• Radiaction often spreads hundreds/ thousands of km to surrounding countries and areas

Question 32

Rank the start-up times of these power stations in order of fastest to slowest:
( Nuclear, Renewable energy resources, Oil, Gas Coal)

Answer 32

Fastest

1. Renewable energy resources (wind, hydroelectric, wave)
2. Gas
3. Oil
4. Coal
5. Nuclear

Slowest

Question 33

Why are some power stations are in constant operation whereas others may be switched on and off?

Answer 33

Nuclear power stations and coal-fired power stations usually provide ‘base load’ electricity - they are run all the time because they take the longest time to start up. Oil-fired and gas-fired power stations are often used to provide extra electricity at peak times, because they take the least time to start up, meaning they can meet the energy demand quickest without having to predict and start before.

Question 34

What is the base load?

Answer 34

The base load is the minimum level of demand on an electrical grid over a span of time; the lowest point of energy demand

Question 35

compare some of the advantages and disadvantages of various energy resources.

Answer 35

Burning oil and gas releases pollution which increases global warming. Nuclear fuel does not create greenhouse gases when making energy . Only a very small amount of nuclear fuel is needed to make a lot of energy. Supplies of nuclear fuel will run out in 50 years. On the other hand, renewable energy resources have a near instant staty up time and produce no CO2 pollution, however, they are unreliable and often need a lot of the resource (eg: tidal energy needs at least a 5m change in tide to produce a substantial amount of energy) to produce substantial amounts of energy.

Question 36

compare energy resources in terms of capital and operational costs.

Answer 36

Renewable energy sources such as wind farms and hydroelectricity often have high additional expenses however have very low operational costs. On the other hand, unrenewable energy sources such as nuclear power stations and fossil fuel power stations are much more expensive overall as they have high capital and innitial costs whilst also having high operational costs.

Question 37

What are the most important design considerations for power plant construction?

Answer 37

• Location and site selection.
• Plant layout and configuration.
• Material and equipment selection.
• Energy efficiency and emission reduction.
• Safety and security.
• Surrounding area/ environment

Question 38

What causes acid rain?

Answer 38

Buring fossil fuels which contain sulfur (Natural Gas and crude oil)

Question 39

Why does the voltage across the overhead cables of the National Grid need to be much higher than the output voltage from the power station generators?

Answer 39

By increasing the voltage, currents are reduced. This reduces energy lost through heat and this increase the efficiency of transmission. Therefore, the voltage must be higher to decrease the current and therefore reduce the amount of energy lost.