Energy Use and Renewable Sources
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Questions and Answers

Explain how heat spreads and give an example of a process where this occurs.

Heat spreads through conduction, convection, and radiation; for example, in a boiling pot of water, heat moves from the stove to the water through conduction.

Identify two renewable energy sources and discuss one advantage of each.

Two renewable energy sources are solar energy and wind energy. Solar energy is abundant and reduces reliance on fossil fuels, while wind energy has a low environmental impact during operation.

Describe the process of energy transformation that occurs in a hydroelectric power station.

In a hydroelectric power station, mechanical energy from moving water is transformed into electrical energy through turbines and generators.

What are fossil fuels, and why are they considered non-renewable?

<p>Fossil fuels, such as oil, coal, and natural gas, are formed from decomposed organic matter over millions of years and are considered non-renewable because they deplete faster than they can be replenished.</p> Signup and view all the answers

Explain the environmental impact of biomass as an energy source.

<p>Biomass can contribute to deforestation and habitat loss if not sourced sustainably, but it can also reduce waste and provide renewable energy if managed properly.</p> Signup and view all the answers

Discuss the role of nuclear energy in energy production and one associated risk.

<p>Nuclear energy plays a significant role in generating large amounts of electrical energy without greenhouse gas emissions, but risks include radiation exposure and potential catastrophic failures.</p> Signup and view all the answers

How does solar energy convert into electrical energy using solar panels?

<p>Solar energy is converted into electrical energy in solar panels through photovoltaic cells, which generate electricity when exposed to sunlight.</p> Signup and view all the answers

What is the significance of discussing energy sources' pros and cons in energy management?

<p>Discussing the pros and cons of energy sources is significant in energy management as it helps in making informed decisions that balance efficiency, environmental impact, and sustainability.</p> Signup and view all the answers

Describe how waves can be used as an energy source and the process involved.

<p>Waves can be used as an energy source through wave energy converters that capture the kinetic energy from wave movement and convert it into electrical energy.</p> Signup and view all the answers

What is energy conservation, and why is it important in today's context?

<p>Energy conservation is the practice of using less energy by implementing more efficient practices and technologies; it is important today to combat climate change and ensure energy availability for future generations.</p> Signup and view all the answers

What are the main types of renewable energy sources mentioned?

<p>Hydropower, biomass, wind energy, solar energy, and wave energy.</p> Signup and view all the answers

How does wind energy convert to electrical energy?

<p>Wind energy causes the blades of wind turbines to spin, which converts mechanical energy into electrical energy.</p> Signup and view all the answers

What transformation occurs in a hydroelectric power plant?

<p>The mechanical energy from moving water is transformed into electrical energy.</p> Signup and view all the answers

What is a key disadvantage of fossil fuels?

<p>Fossil fuels release carbon dioxide when burned, contributing to climate change.</p> Signup and view all the answers

How does biomass energy generate heat for homes?

<p>Biomass materials, like pellets and wood chips, are burned to create heat for water and space heating.</p> Signup and view all the answers

Explain how solar panels convert energy from the sun.

<p>Solar panels convert sunlight (radiant energy) into electrical energy using photovoltaic cells.</p> Signup and view all the answers

What energy transformation occurs in nuclear power plants?

<p>Nuclear energy is transformed into heat energy, which is then converted into electrical energy.</p> Signup and view all the answers

Discuss one environmental concern associated with hydropower.

<p>Hydropower can disrupt local ecosystems and wildlife habitats due to dam constructions.</p> Signup and view all the answers

What role do fossil fuels play in energy production?

<p>Fossil fuels are burned to generate electricity, provide heat, and power vehicles.</p> Signup and view all the answers

Which renewable energy source is described as being developed rapidly and why?

<p>Solar energy is developed rapidly due to advancements in technology and decreasing costs.</p> Signup and view all the answers

How does increasing temperature affect the motion of molecules in a solid material?

<p>Increasing temperature causes the molecules in a solid to move more vigorously and require more space, leading to expansion.</p> Signup and view all the answers

What role does air play in the conduction and convection of heat in a building?

<p>Air acts as an insulator and carrier of heat; warm air rises while cold air sinks, creating a circulation.</p> Signup and view all the answers

What distinguishes the heat transfer properties of metals from those of non-metals?

<p>Metals conduct heat more efficiently due to their molecular structure, allowing for faster movement of heat compared to non-metals.</p> Signup and view all the answers

Explain how solar radiation contributes to the melting of ice.

<p>Solar radiation provides energy that increases the movement and vibration of water molecules in ice, leading to its melting.</p> Signup and view all the answers

In what way does the expansion of gases relate to their temperature changes?

<p>As the temperature of a gas increases, its molecules move more energetically, causing the gas to expand and occupy more space.</p> Signup and view all the answers

What happens to the movement of atoms and molecules when a solid like ice is heated?

<p>They gain energy and begin to move more freely, causing the ice to melt.</p> Signup and view all the answers

Why does warm air rise while cold air sinks?

<p>Warm air is less dense than cold air, causing it to rise and allowing the cold air to sink.</p> Signup and view all the answers

How does the insulation material affect heat transfer?

<p>Insulation slows down the transfer of heat, making it harder for heat to escape from or enter a space.</p> Signup and view all the answers

What is the effect of heating a metal on its structure?

<p>The heat causes the metal’s molecules to move more and require more space, leading to thermal expansion.</p> Signup and view all the answers

How does the concept of thermal conductivity compare between metals and non-metals?

<p>Metals have a higher thermal conductivity than non-metals, allowing heat to transfer quickly through them.</p> Signup and view all the answers

What unit is used to measure energy, including heat?

<p>The energy is measured in joules, J.</p> Signup and view all the answers

How does temperature change affect the movement of molecules in a solid like ice?

<p>Heating ice causes the molecules to move faster and transition into a liquid state.</p> Signup and view all the answers

Why does a warm metal expand when heated?

<p>The heat causes the metal's molecules to move more, requiring more space.</p> Signup and view all the answers

What is thermal conduction, and how does it differ between metals and non-metals?

<p>Thermal conduction is the transfer of heat within a material, and it occurs more efficiently in metals than in non-metals.</p> Signup and view all the answers

What happens to the density of air when it's heated?

<p>Heated air becomes less dense and rises because it expands and occupies greater volume.</p> Signup and view all the answers

Study Notes

Energy Use

  • Energy use has increased significantly in the past 100 years.
  • Developed countries use more energy than developing countries.
  • There are concerns about whether there will be enough energy for everyone in the future.
  • It is possible to reduce the use of fossil fuels.

Electricity

  • Electricity is a valuable form of energy.
  • It is easy to convert electricity into other forms of energy.
  • Electricity can be generated in power plants:
    • Hydroelectric power plants
    • Wind power plants
    • Nuclear power plants

Hydroelectric Power

  • Hydroelectric power is a renewable energy source.
  • The mechanical energy of water is converted into electricity.
  • Hydroelectric power can impact wildlife and the environment.

Biomass

  • Biomass is a renewable energy source.
  • Examples include pellets and wood chips.
  • Burning biomass creates heat, which can be used to heat water and homes.
  • The energy transfer involves:
    • Radiation energy → chemical energy → heat energy

Wind Power

  • Wind power is a renewable energy source.
  • Wind turbines convert the kinetic energy of wind into electricity.
  • The mechanical energy of the wind turbine blades is converted into electricity.

Solar Energy

  • Solar power is a renewable energy source.
  • There is rapid development in solar technology.
  • Solar cells contain electrical circuits.
  • Solar radiation is converted into electricity.

Wave Energy

  • Wave energy is a renewable energy source.
  • It uses the kinetic energy of waves to generate electricity.

Fossil Fuels

  • Oil, coal, and natural gas are non-renewable energy sources.
  • They are referred to as "fossil fuels".
  • Fossil fuels can be used to generate:
    • Electricity in coal-fired power plants
    • Mechanical energy in cars
  • Burning fossil fuels releases carbon dioxide, contributing to climate change.

Nuclear Power

  • Nuclear power is a non-renewable energy source.
  • Nuclear energy is converted into electricity in nuclear power plants.
  • Atoms are split in a nuclear reactor.
  • Nuclear energy → heat energy → kinetic energy → electrical energy
  • There is a risk of radiation from a nuclear reactor.

Energy Use

  • Energy consumption has drastically increased over the last 100 years.
  • Richer countries consume considerably more energy than poorer countries.
  • There's ongoing debate about whether we will have enough energy for everyone in the future and whether we can reduce reliance on fossil fuels.

Electrical Energy

  • Electricity is a valuable form of energy because it's easily convertible into other energy forms.
  • Power plants, like hydroelectric, wind, and nuclear power plants, generate electricity.

Hydroelectric Power

  • A renewable source of energy.
  • The mechanical energy (kinetic energy) of water is transformed into electrical energy.
  • It can impact the surrounding environment and wildlife.

Energy Sources

Biomass

  • A renewable energy source.
  • Examples include wood pellets and wood chips.
  • Biomass is burned to generate heat, which can be used for heating water and homes.

Wind Power

  • A renewable energy source.
  • Wind turbines harness the kinetic energy of wind, transforming it into electrical energy.

Solar Cells

  • A renewable energy source.
  • Continuous development and improvement.
  • Solar cells contain electrical circuits that convert radiant energy from the sun into electricity.

Wave Energy

  • A renewable energy source.
  • Wave motion is harnessed to generate electricity.

Fossil Fuels

  • Non-renewable energy sources like oil, coal, and natural gas.
  • Can be used to generate electricity (in coal power plants) and provide power for vehicles.
  • The combustion of fossil fuels releases carbon dioxide, contributing to climate change.

Nuclear Power

  • A non-renewable energy source.
  • Nuclear energy is transformed into electricity in nuclear power plants.
  • Atoms are split in the nuclear reactor to release energy in the form of heat, which is converted into kinetic energy and then into electrical energy.
  • Nuclear reactors produce dangerous radiation.

Heat is energy

  • Heat is a measure of how much atoms and molecules move
  • Energy is measured in joules (J).
  • Heat energy can be:
    • Conduction
    • Convection
    • Radiation
  • Insulation is a material that makes it difficult for heat to conduct.
  • Stationary air is a good insulator.

What is heat really?

  • When the sun shines, we can feel it warming us.
  • The sun gives water molecules more energy, causing them to move faster and more freely.
  • Heat is a measure of the movement of atoms and molecules.

Heat - one of several forms of energy

  • Heat is a form of energy, and the sun's radiant energy is another.

Air can weigh differently

  • When the sun warms a solid substance like metal, interesting things happen.
  • Heat energy causes the molecules to move more.
  • This makes the molecules need more space to move.
  • Therefore, a warm metal takes up more space than a cold metal.
  • We say that the metal expands when it gets hot.
  • A liter of warm air is lighter than a liter of cold air.

Heat moves - it flows

  • Warm air is light and rises towards the ceiling, while cold air is heavy and settles closest to the floor.
  • Heat that is transferred in this way is called convection.

Heat is conducted

  • Heat also moves inside a solid material like metal or wood.
  • Iron quickly conducts heat away from your hand.
  • The amount of energy that is used efficiently is called efficiency, and it is described with a percentage.

Electrical energy - a valuable form of energy

  • Electrical energy is often abbreviated as electricity.
  • Electrical energy can easily be converted into other forms of energy.

Important energy sources

  • Hydropower:
    • Renewable: Yes
    • Energy conversion: Kinetic energy ⇒ electrical energy
    • Advantages:
      • Does not increase the amount of carbon dioxide in the air.
      • Easy to increase and decrease production.
    • Disadvantages:
      • Floods land.
      • Impacts nature and wildlife.
  • Biomass:
    • Renewable: Yes
    • Energy conversion: Chemical energy ⇒ heat + electrical energy.
    • Advantages:
      • Does not increase the amount of carbon dioxide in the air.
      • Available in large quantities in Sweden.
    • Disadvantages:
      • Forest is also needed for timber and paper.
  • Wind power:
    • Renewable: Yes
    • Energy conversion: Kinetic energy ⇒ electrical energy.
    • Advantages:
      • Does not increase the amount of carbon dioxide in the air.
      • Easy to build and demolish.
    • Disadvantages:
      • Only delivers when it's windy.
  • Solar cells:
    • Renewable: Yes
    • Energy conversion: Radiant energy ⇒ electrical energy.
    • Advantages:
      • Does not increase the amount of carbon dioxide in the air.
      • Easy to build.
      • No moving parts.
    • Disadvantages:
      • Only delivers when the sun is shining.
  • Heat pumps:
    • Renewable: Yes
    • Energy conversion: Lowers temperature outside and raises it inside.
    • Advantages:
      • Does not increase the amount of carbon dioxide in the air.
      • Wide range of applications.
    • Disadvantages:
      • Needs electrical energy to function.
  • Wave energy:
    • Renewable: Yes
    • Energy conversion: Kinetic energy ⇒ electrical energy.
    • Advantages:
      • Does not increase the amount of carbon dioxide in the air.
      • Delivers almost year-round.
    • Disadvantages:
      • Complicated to build.
  • Oil, coal, and gas:
    • Renewable: No
    • Energy conversion: Chemical energy ⇒ electrical energy + kinetic energy.
    • Advantages:
      • Easy to use.
      • Available for purchase everywhere.
    • Disadvantages:
      • Increases the amount of carbon dioxide in the air.
      • Will run out eventually.
  • Nuclear power:
    • Renewable: No
    • Energy conversion: Nuclear energy ⇒ electrical energy.
    • Advantages:
      • Relatively easy to increase and decrease production.
      • Does not increase the amount of carbon dioxide in the air.
    • Disadvantages:
      • Dangerous radiation can leak out.
      • Complicated to build.
      • Will run out eventually.

We use more energy

  • Today, we use a lot more energy in the world than we did 100 years ago, maybe ten times more.
  • Richer countries use more energy than poorer countries.

Energy on a playground

  • In a swing, mechanical energy is in focus.
  • Mechanical energy is actually a collective term for the two energy forms: potential energy and kinetic energy.
  • When the swing is at its highest point, all kinetic energy has been converted into potential energy.
  • When the swing falls, potential energy is gradually converted into kinetic energy.
  • In a climbing frame, you first use energy to climb up.
  • The chemical energy in food is converted to kinetic energy in the muscles.
  • The higher you climb, the greater your potential energy.
  • When you take the slide down, almost all of the potential energy is converted to kinetic energy.

Can this continue?

  • We are not using more energy today than we did in 1990.
  • Most vehicles still run on gasoline or diesel.

Everyone can get better

  • All of the world's countries have the opportunity to get better without an increase in energy use worldwide.

Fossil fuels - non-renewable energy sources

  • Fossil fuels are the common term for oil, coal, and natural gas.
  • They began to be used on a large scale in the 20th century in vehicles, boats, and airplanes.
  • When these fuels burn in an engine, carbon dioxide is formed.
  • Fossil fuels contribute to a warmer climate.
  • In Sweden, we use almost no fossil fuels to heat water and homes.

Nuclear power - non-renewable energy source

  • In a nuclear reactor, atoms are split in half.
  • The heat comes from the nuclear energy that holds the atomic nucleus together.
  • When the atom is split, nuclear energy is no longer needed.
  • The heat is used to boil water.
  • Steam drives a turbine, which in turn drives an electric generator.

Why is energy discussed so much?

  • The main reason: It is the threat of a warmer climate on Earth.
  • Researchers are convinced that the change is caused by the fact that we are burning too much oil, coal, and gas.

Heat is Energy

  • Heat is a measure of how much atoms and molecules move.
  • Heat energy can be conducted, convected, or radiated.
  • Insulation is a material that makes it difficult for heat to flow.
  • Still air is a good insulator.

What is Heat Really?

  • When the Sun shines, we can feel it warming us.
  • Atoms are constantly moving.
  • In solids, like ice, atoms move a little.
  • When the sun shines on ice on a spring day, the ice melts because the water molecules receive more energy from the sun, making the molecules move faster and more freely.
  • Heat is a measure of the movement of atoms and molecules.

Heat - One Type of Energy

  • Solar radiation contains radiant energy that is converted into heat energy when it hits ice and water.
  • Heat is a form of energy and the sun's radiant energy is another form of energy.

Air Can Weigh Differently

  • When the sun heats a solid like metal, the heat energy causes molecules to move more.
  • This makes the molecules need more space to move, causing the hot metal to take up more space than a cool metal.
  • We say that the metal expands when it becomes warm.
  • When air is heated, its molecules move more and take up more space.
  • This means that one liter of warm air is lighter than one liter of cold air.

Heat Moves - It Flows

  • Heat can be moved using various methods:
    • Warm elements beneath windows
    • Heat coils in the floor
    • Fans that circulate warm air.
  • Warm air is light and rises towards the ceiling, while cold air is heavy and stays closest to the floor.
  • Heat that is moved in this way is called convection.

Heat is Conducted

  • Heat also moves within a solid material, such as metal or wood.
  • Iron conducts heat better than wood.
  • This is because iron molecules move easier than wood molecules.
  • When you touch an iron railing, the iron conducts heat away from your hand quickly.

Fossil Fuels - Non-Renewable Energy Sources

  • Fossil fuels include oil, coal, and natural gas.
  • Fossil fuels began to be used on a large scale in the 20th century in vehicles, boats, and airplanes.
  • When fossil fuels are burned in an engine, carbon dioxide is produced.
  • Fossil fuels contribute to a warmer climate.

Nuclear Power - Non-Renewable Energy Source

  • A lot of the electricity used in Sweden is created in nuclear power plants
  • Nuclear energy is generated from the atom's nucleus
  • In a nuclear reactor, atoms are split into two smaller atoms, plus a huge amount of energy in the form of heat.
  • This heat comes from the nuclear energy that holds the atom's nucleus together.
  • When an atom is split, the nuclear energy is no longer needed.
  • Instead, it can be captured and converted into electricity.
  • The heat in the reactor is used to boil water.
  • The steam generated drives a turbine, which rotates an electric generator.
  • This converts heat into kinetic energy and then into electrical energy.

Why Is Energy Discussed So Much?

  • Climate change is a threat caused by burning too much oil, coal, and gas.
  • This produces carbon dioxide that stays in the atmosphere, trapping heat and warming the planet.
  • Scientists are convinced that climate change is caused by the increased carbon dioxide in the atmosphere from burning fossil fuels.

Water Power - An Example of a Renewable Energy Source

  • The sun constantly creates clouds filled with water vapor.
  • Water power does not run out.
  • Water power can be used to generate electricity.
  • The downside is that water power plants affect nature and wildlife by collecting water in large dams.

Wood is a Renewable Energy Source

  • Solar energy makes forests grow.
  • The sun's radiant energy is converted into chemical energy, creating wood.
  • Biomass can be used to heat water and homes.
  • Wood pellets and wood chips are examples of biomass.

We Use Energy

  • Renewable energy sources are those that do not run out, such as hydropower, wind power, biofuels, and solar energy.
  • Non-renewable energy sources are those that will eventually run out, such as coal, oil, natural gas, and nuclear power.
  • Coal, oil, and natural gas are called fossil fuels.

Heat is energy

  • Heat is a measure of how much atoms and molecules move
  • Heat energy can be conducted, convected, and radiated.
  • Insulation is a material that makes it difficult for heat to flow.
  • Still air is a good insulator.

What is heat really?

  • Atoms are constantly moving.
  • In solid substances, such as ice, the atoms move a little.
  • As the sun shines on ice, the water molecules receive more energy which makes them move faster and more freely.
  • Heat is a measure of the movement of atoms and molecules.

Heat - one of several forms of energy

  • The sun’s rays contain radiant energy that is transformed into heat when the rays hit the ice and water.
  • Heat is a form of energy and the sun’s radiant energy is another.

Air can weigh differently

  • When the sun heats a solid substance like metal, the heat energy causes the molecules to move more, requiring more space to move around.
  • This makes a warm metal take up more space than a cold metal.
  • When air is heated up, the molecules move more and take up more space, meaning that a liter of warm air is lighter than a liter of cold air.

Heat moves - it convects

  • Warm air is light and rises towards the ceiling, while cold air is heavy and settles closest to the floor.
  • Heat that is transferred this way is called convection.

Heat is conducted

  • Heat also moves inside a solid material, such as in metal or wood.
  • The difference in temperature between a metal railing and a wooden railing is because molecules move more easily in iron than in wood.
  • When you touch an iron railing, the iron quickly conducts the heat away from your hand.
  • The efficiency of energy utilization is called efficiency and is described as a percentage.
  • An efficiency of 90% means that most of the energy is utilized, only 10% becomes unusable heat

Electrical energy - a valuable form of energy

  • Electrical energy is the most valuable form of energy we have.
  • Electrical energy can easily be converted into other forms of energy such as heating water in a washing machine, keeping a refrigerator cold, and driving trains just as well as electric bicycles.

Important energy sources

  • Hydropower

    • Renewable: Yes
    • Energy conversion: Kinetic energy ⇒ electrical energy
    • Advantages:
      • Does not increase the amount of carbon dioxide in the air.
      • Easy to increase and decrease production.
    • Disadvantages:
      • Floods land.
      • Affects nature and wildlife.

  • Biomass

    • Renewable: Yes
    • Energy conversion: Chemical energy ⇒ heat + electrical energy
    • Advantages:
      • Does not increase the amount of carbon dioxide in the air.
      • Available in abundance in Sweden.
    • Disadvantages:
      • Forests are also needed for timber and paper.

  • Wind power

    • Renewable: Yes
    • Energy conversion: Kinetic energy ⇒ electrical energy
    • Advantages:
      • Does not increase the amount of carbon dioxide in the air.
      • Easy to build and dismantle.
    • Disadvantages:
      • Only delivers when it is windy.

  • Solar cells

    • Renewable: Yes
    • Energy conversion: Radiant energy ⇒ electrical energy
    • Advantages:
      • Does not increase the amount of carbon dioxide in the air.
      • Easy to build.
      • No moving parts.
    • Disadvantages:
      • Only delivers when the sun shines.

  • Heat pumps

    • Renewable: Yes
    • Energy conversion: Lowers the temperature outside and raises it inside.
    • Advantages:
      • Does not increase the amount of carbon dioxide in the air.
      • Wide range of applications.
    • Disadvantages:
      • Needs electrical energy to operate.

  • Wave energy

    • Renewable: Yes
    • Energy conversion: Kinetic energy ⇒ electrical energy
    • Advantages:
      • Does not increase the amount of carbon dioxide in the air.
      • Delivers almost year-round.
    • Disadvantages:
      • Complicated to build.

  • Oil, coal and gas

    • Renewable: No
    • Energy conversion: Chemical energy ⇒ electrical energy + kinetic energy.
    • Advantages:
      • Easy to use.
      • Available for purchase everywhere.
    • Disadvantages:
      • Increases the amount of carbon dioxide in the air.
      • Will run out.

  • Nuclear power

    • Renewable: No
    • Energy conversion: Nuclear energy ⇒ electrical energy.
    • Advantages:
      • Relatively easy increase and decrease production.
      • Does not increase the amount of carbon dioxide in the air.
    • Disadvantages:
      • Dangerous radiation can leak out.
      • Complicated to build.
      • Will run out.

We use more energy

  • We use much more energy in the world today than we did 100 years ago, perhaps ten times more.
  • This varies from country to country.
  • Rich countries use more energy than poor countries.

Energy on a playground

  • The mechanical energy is essentially a collective term for the two forms of energy: potential energy and kinetic energy.
  • When the swing reaches its highest point, the swing stands still for a moment.
  • At this point, all the kinetic energy has been converted into potential energy.
  • As the swing falls downwards, potential energy is gradually converted into kinetic energy.
  • When you pass the lowest point, the potential energy has been converted into kinetic energy.

Can this continue?

  • In Sweden, we use almost no fossil fuels to heat water and homes.
  • When it comes to transport, we are worse off. Most vehicles still run on gasoline or diesel.

Everyone can get better

  • It means that all the countries of the world have the opportunity to improve without increasing global energy consumption.

Fossil fuels - non-renewable energy sources

  • Fossil fuels are the common term for oil, coal and natural gas.
  • They began to be used on a large scale in the 20th century in vehicles, boats and aircraft.
  • When these fuels burn in an engine, they produce carbon dioxide.
  • Today we know with great certainty that fossil fuels contribute to a warmer climate.
  • The sooner we manage to stop using these energy sources, the better for the climate.
  • In Sweden, we have come a long way.

Nuclear power - non-renewable energy source

  • A large part of the electricity we use in Sweden is generated in our nuclear power plants.
  • Today we have power plants in three different places in Sweden.
  • The energy that is utilized comes from the atom's inner core.
  • In a nuclear reactor, atoms are split in half.
  • The result of the division is two smaller atoms plus large amounts of heat.
  • The heat comes from the nuclear energy that holds the atomic nucleus together.
  • When the atom is divided, the nuclear energy is no longer needed.
  • Instead, it can be utilized and converted into electrical energy.
  • The heat is used to boil water.
  • The steam produced drives a turbine which in turn drives an electric generator, converting heat into kinetic energy and further into electrical energy.

Where does the electricity really come from?

  • One of the very best energy sources is running water in rivers.
  • When water rushes, kinetic energy can be captured in special machines called electric generators, where the kinetic energy of the water is converted into electrical energy.
  • The kinetic energy of the water actually comes from the sun’s rays that lift water vapor from lakes and seas up to the clouds.

Using energy smartly

  • To efficiently use energy is the same as buying a new refrigerator that keeps food cold but uses less energy than the old refrigerator.
  • If everyone thinks that way, both at home and at work, we will soon use significantly less energy than we do today in the world.

Energy in different forms

  • There are six forms of energy:
    • Heat energy
    • Mechanical energy
    • Electrical energy
    • Chemical energy
    • Radiant energy
    • Nuclear energy
  • Mechanical energy is usually divided into potential energy and kinetic energy.
  • The energy principle: Energy cannot be destroyed or created, only converted between different forms.
  • Efficiency tells us what proportion of the energy has been utilized.
  • The higher the efficiency, the more energy has been utilized.

More renewable energy sources

  • Wind turbines are being built to capture more of the wind's energy.
  • One wind turbine creates about as much electricity in a year as 500 families use.
  • Solar cells convert radiant energy directly into electrical energy.
  • The price of solar cells is falling, leading to the construction of even more solar cell parks.
  • Wave machines capture the kinetic energy of waves and convert it into electricity.
  • Heat pumps take heat from the outside air and transfer the energy to the inside air.

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Description

Explore the evolution of energy use over the last century, focusing on different sources like electricity, hydroelectric power, and biomass. Understand the impact of energy consumption on the environment and the potential for reducing reliance on fossil fuels. This quiz covers key concepts in sustainable energy practices and developments.

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