TRIPLE ONLY: Energy resources and electricity generation

We can divide energy resources in two categories: renewable and non-renewable

What is meant by the term renewable energy resource? What about non-renewable?

Energy supplies that won’t be completely used up in time as it is replenished at a faster rate than the rate at which it is being used

Energy source that will not last forever and cannot be replaced once it has been used. Finite resource

Examples of renewable and non-renewable energy resources

• Renewable energy resources include:

  • solar heating panels

  • solar cells

  • wind

  • hydroelectricity

  • geothermal

  • wave

  • tidal

• Non-renewable energy resources include:

  • fossil fuels (coal, oil and natural gas)

  • nuclear fuel

Electricity is generated in very similar ways, no matter what energy resource is used.

Describe the general process

• A turbine is turned, which turns a generator, which generates electricity

• The element that differs is how the turbine is made to turn

What are the advantages of using renewable sources vs non renewable? This applies to all renewable energy sources

It does not produce greenhouse gases

What is a reliable vs non-reliable resources?

• A reliable energy resource is one that can produce energy at any time

• Non-reliable resources can only produce energy some of the time (e.g. when it’s windy)

• The demand for electricity varies from hour to hour, day to day and season to season.

• The companies supplying this electricity need to be able to cope with these changes in demand or they are forced to cut off electricity to some consumers

Describe the process of generating electricity using wind + energy stores

• Wind is powered by the Sun’s heat energy and it turns turbines directly which turns a generator which generates electricity

• Energy is transferred from the kinetic store of the wind to the KE of turbine mechanically to the KE store of the generator

• Power can only be harvested in regions where the wind blows with enough energy for a significant portion of the year

• Wind farms change the appearance of the landscape (environmental damage)

• They cause noise pollution

• May kill birds and bats

Advantages + disadvantages of wind?

Advantages

• Produces no pollution or CO2

• Cheap to build and maintain

Disadvantages

• Non-reliable (strength, direction and frequency varies) *

• Power can only be harvested in regions where the wind blows with enough energy for a significant portion of the year and in the right direction

• Wind farms change the appearance of the landscape *

• They cause noise pollution

• May kill birds and bats

Describe the process of generating electricity using hydroelectric dams + energy stores

What is the role of the Sun in this process?

• Water is stored at a height (usually in a dam), and when released, the moving water is used to turn turbines directly which turns a generator, which generates electricity

• Energy is transferred from the gravitational potential store of the water, to the kinetic store of the water as it flows down, to the kinetic store of the turbine, to the kinetic store of the generator

• The Sun causes water to evaporate. This water falls as rain to be collected in reservoirs and used again.
  

Advantages + disadvantages for hydroelectric?

Advantages

• Can respond to meet changes in demand quickly

• Renewable so no pollution or CO2 produced (unless a pump is used to return the water as this uses fossil fuels)

Disadvantages

• Building reservoirs and power stations can spoil the landscape

• May involve flooding large areas to build reservoirs, destroying natural habitats and displace wildlife

What is something hydroelectric power stations can do but others can’t?

• Many power stations (like nuclear) are most efficient when they run at a steady pace and cannot be turned off quickly

• At night, when the demand for electricity is low, the extra electricity is wasted

• However, hydroelectric power stations can use the extra electricity to pump water uphill into high level reservoir.

• This converts electrical energy into GPE stored in the water

• Then this GPE can be re-transferred when needed

Describe the process of generating electricity using tidal power + energy stores

What is the role of the Sun in this process?

• Water is stored at a height (usually by a tidal barrage) at high and low tide, when released the moving water is used to turn turbines directly, which turn a generator, which generates electricity

• Energy is transferred from the gravitational potential store of the water, to the kinetic store of the water, to the kinetic store of the turbine, to the kinetic store of the generator

• The energy for the movement of the tides is provided by the gravitational pull of the Moon and the Sun (uses only a bit)

Advantages + disadvantages for tidal?

Advantages

• Tides are predictable so energy can be produced at regular intervals

Disadvantages

• Few suitable locations

• Dams affect the rise and fall of water and is likely to damage aquatic life and disrupt shipping

• In textbook but not save my exams: not available continuously

Describe the process of generating electricity using wave energy + energy stores

Why is this energy (and the other 2 above) a renewable source?

• The motion of the water due to waves is used to turn turbines directly, which turn a generator, which generates electricity

• Energy is transferred from the kinetic store of the water to the kinetic store of the turbine, to the kinetic store of the generator

• The movement of energy of the waves is continuously available

Advantages + disadvantages for wave energy?

There are no problems al parecer: renewable, does not produce pollution (greenhouse gases or unwanted waste products)

Describe the process of generating electricity using geothermal energy + energy stores

What are some of the problems?

• Hot rocks underground are used to heat water to produce steam that turns turbines, which turn a generator, which generates electricity

• Energy is transferred from the thermal store of the rocks, to the thermal store of the water, to the kinetic store of the turbine, to the kinetic store of the generator

Advantages + disadvantages for geothermal?

Advantages

• Reliable

• Doesn’t release greenhouse gases (aunque en save my exams dice que can release methane in the extraction process)

Disadvantages

• Not many suitable locations

Solar heating systems are used for 2 things:

Widely used to provide water heating (warm water) in households

Generate electricity

Describe the process of warming up water using solar heating systems + energy stores.

What is the role of the Sun in this process?

The Sun emits thermal radiation which are absorbed by the panels

Water heating

• Solar heating panels use sunlight to heat water in small pipes within the panel to produce warm water for households

• Energy is transferred from the nuclear store of the Sun, to the thermal store of the panel, to the thermal store of the water

• Solar heating panels absorb thermal radiation (IR) and use it to heat water

Describe the characteristics of solar panels that are made to transfer as much energy to the water passing through them as possible

• Pipes made of copper and brazed onto a copper sheet — copper is a good conductor of heat

• The surfaces of the sheet and the pipes should have a matte black finish as this is the best absorber of thermal radiation

• The glass traps a layer of air above the copper to help insulate the unit and retain the heat

• The backing is designed to stop heat escaping to the surroundings

Describe the process of generating electricity using solar heating systems + energy stores.

Generate electricity

• Curved mirrors are used to focus thermal radiation onto a boiler in a tower

• The mirrors are controlled to reflect the Sun’s heat onto the central tower throughout the day.

• The steam is used to drive turbines which can be used to drive electricity generators

• Energy is transferred from the nuclear store of the Sun to the thermal store of the the boiler to the kinetic store of the steam to the kinetic store of the turbines to the kinetic store of the generators

Advantages + disadvantages for solar heating systems?

Advantages

• Renewable so no pollution or greenhouse gases

• Good for electricity production in remote areas

Disadvantages

• Non-reliable as it only produces energy when the Sun is shining

Describe the process of generating electricity using solar cells + energy stores

What is the role of the Sun in this process?

What are some of the problems?

• Solar cells use transfer light energy (sunlight — EM radiation) directly to electrical energy, producing a current

• When sunlight falls on solar cells, electrons are released from the metal in the solar cell, which can be directed into a circuit, producing a current

• Energy is transferred by radiation from the nuclear store of the Sun, to the thermal store of the solar cell

Advantages + disadvantages for solar cells?

Advantages

• Renewable so no pollution or greenhouse gases

• Good for electricity production in remote areas

Disadvantages

• Non-reliable as it only produces energy when the Sun is shining

• Each solar cell only produces a small amount of electricity so many cells are needed. PV farms spoils the countryside + good farming land is lost

Describe the process of generating electricity using fossil fuels + energy stores

• Fossil fuels are combusted to heat water to produce steam that turns turbines to generate electricity

• Energy is transferred from the chemical store of the fuel, to the thermal store of the water, to the kinetic store of the turbine, to the kinetic store of the generator

Advantages + disadvantages of fossil fuels?

Advantages

• Reliable

• They can be turned on quickly (although it takes a few hours until electricity is produced) so can respond to changes in demand

• Can produce large amounts of energy consistently.

Disadvantages

• They release greenhouse gases like CO2 which trap heat energy and leads to global warming

  • Global warming leads to: rising sea levels, destruction of habitats, etc

• Coal and oil contain sulfur. When they are burned it releases sulfur dioxide which combines with water to form acid rain.

  • acid rain damages people, plants and buildings

• Fossil fuels also provide chemicals that are used to manufacture many products. Once burned for energy production, these chemical resources are lost permanently.

Levels of acid rain are lower in Europe than in developing countries

Sulfur can be removed from the fuels + sulfur dioxide can be removed from the waste gases as well but both these things increases the cost.

There is no practical way of avoiding the release of CO2

Describe the process of generating electricity using nuclear power + energy stores

• Nuclear fuels (e.g uranium) are reacted to heat water to produce steam that turns turbines to generate electricity

• Energy is transferred from the nuclear store of the fuel, to the thermal store of the water, to the kinetic store of the turbine, to the kinetic store of the generator

Advantages + disadvantages for nuclear power?

Advantages

• Reliable

• It doesn’t produce greenhouse gases

• Large amounts of energy are produced from small amounts of fuel (cost of energy pe unit of fuel is low)

• Produces large amounts of energy consistently

Problems

• Produces radioactive waste materials that takes thousands of years to decay (accidents) and must be safely disposed of (when the useful life of nuclear power station comes to an end)

  • Other power station plants can be demolished

• Nuclear power stations are expensive to build and maintain and take many years to build

• Cannot respond to changes in demand because it cannot be turned off and on quickly

Why is uranium a non-renewable resource?

The uranium in the Earth was formed before the Solar System was formed, so once it has been used there will be no further supplies

What is the payback time?

Describe and explain how the pay-back time for nuclear power compares to that of wind farms

The payback time is how long it takes for the income from selling electricity to cover the cost of building the power station

• Although the running costs of nuclear power are relatively low, the pay back time is very long

• The cost of setting up a wind farm is lower and there are no fuel costs. However the amount of energy produced by wind farms is lower than the amount produced by nuclear power stations. The pay-back time is also quite long