Unit 1: Chapter 4 - Generating Electricity

Question 1

Energy from Wind and Water

What are the 4 ways to produce electricity through wind and water?

Answer 1

WIND POWER (PROs and CONs) 
\+ Renewable as there is constant supply of wind to turn the blades or a turbine to turn the generator.
- Very situational. Needs to be in a certain area to produce the maximum energy yield.

WAVE POWER (PROs and CONs)

+Constant supply of energy usually.

• Generator could be damaged
• tidal flow patterns change, affecting the habitats and marine life.

HYDROELECTRIC POWER (PROs and CONSs)

+ Good emergency power as a release of water can turn the generator very fast.

• Once used, it may take a lot of time to collect water in reservoir.
• Potentially dangerous as there is a lack of warning if water is released.

TIDAL POWER (PROs and CONs)

+Constant supply of electricity produced.
- Very situational. Needs to have a rapid flow of water

Question 2

Fuel for electricity

Explain how a fossil-fuel power station works.

What are the 3 ways to produce electricity or energy by burning or using a power station?

Answer 2

A fossil-fuel power station works turning a turbine of a generator to supply electricity.
Firstly, fossil fuels are burned to heat the boiler and produces steam and leads to the turbine. The turbine spins the generator to produce electricity. Hot water is returned to the cooling tower to repeat the process.

FOSSIL FUELS (PROs and CONs)

+ Can produce electricity very quickly

• a large amount of waste gases are produced e.g. Nitrogen oxides and sulphur dioxides as well as carbon dioxides.
• fossil fuels are non-renewable and will eventually run out

BIOFUELS (PROs and CONs)

+ Renewable as it is a biological species that will never die out.

+ Carbon-neutral because in theory, the CO2 taken in can balance the CO2 released.

• A lack of biodiesel to power the world.
• Large amounts of land required to create energy

NUCLEAR POWER (PROs and CONs)
Works similarly to fossil fuel power station

+ Produces large amounts of energy from NUCLEAR FISSION.

+ No greenhouse gases

• Very dangerous if the waste is not stored properly and can affect areas for years.

Question 3

Power from the Sun and Earth

Answer 3

We can generate electricity using solar panels. Or we can heat water directly in solar heating panels.

SOLAR CELLS (PROs and CONs)

+Useful to power things that require small amounts of electricity

-We need lots of them - and plenty of sunshine - to generate enough electricity to be useful but it is also quite expensive.

SOLAR HEATING PANELS (PROs and CONs)

+Even on cloudy days it can supply enough water.

-Expensive to install

HOW DOES A SOLAR POWER TOWER WORK?

• Thousands of mirrors reflect sunlight onto a large water tank at the top of the tower.
  Mirrors on the ground surrounds the base of the tower.
• The water in the tank is turned into steam by the solar radiation.
• The steam is piped down to the ground, turning electricity generators.
• The mirrors are controlled by computers so they track the sun.

GEOTHERMAL ENERGY (PROs and CONs)

Geothermal energy comes from energy released by radioactive substances deep within the Earth. Water + hot rocks = steam.

+Constant production of electricity
+Renewable

-Very situational as it power plants can only be built in volcanic areas or where there are hot rocks below the surface.

Question 4

Renewable energy sources and the environment

Answer 4

ADVANTAGES

• They will never run out
• They do not produce greenhouse gases and acid rain
• They do not create radioactive waste
• They can be used where connection
  to the National Grid is uneconomic. For example, solar cells can be used for road signs and hydroelectricity can be used in remote areas.

DISADVANTAGES

• Wind turbines are loud and can upset them. They are also sometimes considered unsightly.
• Tidal barrages affect river estuaries and habitats of creatures and plants there.
• Hydroelectric schemes need large resevoirs of water, which can affect nearby animal and plant life. Habitats are often flooded.
• Solar cells would need to cover large areas to generate large amounts of power.

Question 5

The National Grid

What is the National Grid Voltage? Why?

What are transformers?

How much V do power plants produce?

What is the V of underground mains?

Answer 5

National Grid Voltage: 132,000V+

This is to reduce power loss, making the system more efficient.

Transformers are used to increase and decrease voltage.

Power stations produce 25,000V. This voltage is then increased to 132,000V with a step-up transformer.

Electricity pylons then carry the high voltage cables and then decreased to 230V to then be carried to the underground mains cable to houses.

Question 6

Big Energy Issues

Answer 6

RENEWABLE SOURCES ARE UNRELIABLE

Hydroelectric: Upland reservoir could run dry.

Wind, waves: Wind and waves waves are too weak on calm days.

Tidal: Height of tide varies both on monthly and yearly cycle.

Solar: No solar energy at night and variable during the day.

DEMAND FOR ELECTRICITY

Power stations start up relatively quickly.
Nuclear, coal and oil energy provide a constant amount of electricity.
Renewable sources when demand is high are also used and are in operation.
Renewable energy that is produce can be stored for later use.