Unit 5. Energy. 5 primary / Natural Science Pedro Antonio López Hernández

Transcription

1 Unit 5. Energy 5 primary / Natural Science Pedro Antonio López Hernández

2 What is energy? Energy has no mass and occupies no space but it makes things happen. We know it exists because we see the effects it produces on other things. Nothing happens without energy. Forms of energy Kinetic energy This energy is produced by mass in movement, like the wind o a car. Potential energy This is the stored energy an object has because of its elevation above the ground. A book on a shelf has potential energy. Mechanical energy This energy is the sum of kinetic and potential energy. For example: a roller coaster car is both in movement (it has kinetic energy) and at several metres above the ground (It has potential energy): so it has mechanical energy. Light energy Lightning and some bodies like the sun emit energy in the form of light. Electrical energy We find in bolts of lightning when there is a storm. We can also make a form of energy artificially using falling water or by burning petrol or coal. It is the most common energy because it is easy to transform into other forms of energy. Heat energy Some bodies like the sun, fire or the lava of a volcano emit energy in the form of heat. Chemical energy Nuclear energy This energy is stored in certain substances like the food we eat, oil and coal. We get this form of energy from certain minerals like uranium.

3 Properties of energy 1 2 We can transfer energy Energy can pass from one body to another. If you line up a row of dominoes and knock over the first one, they will all fall down, one by one. This is because each domino transfers energy to the next domino in the row. We can transform energy One form of energy can be transformed into another form. Electrical energy can be transformed into light energy in a light bulb, into heat energy in a radiator or into mechanical energy in a fan. This is what makes it so useful. 3 4 We can transport energy We can store energy Batteries can store chemical energy making it ready for us to use when we need it. The food we eat is also a store of energy for our bodies. We can take energy from one place to another. We transport electrical energy using cables from where we produce it, to where we use it. Oil and gas, which contain chemical energy, can be transported in ships.

4 Sources of energy The energy we use comes from energy sources. Sources of energy are reserves of energy which we find in nature. These sources can be renewable or non-renewable. Renewable energy sources Non-renewable energy sources They are natural resources which do not run out because they are quickly replenished. They are natural resources which will run out, because we are consuming them faster than they replenish. Solar energy The sun is the source of solar radiation. Depending on how we collect it, this can produce electrical energy or heat energy. Wind energy Wind turbines transform the mechanical energy of the wind into electrical energy. Fossil fuels We use coal, gas or oil to move vehicles and for heating. In thermoelectric power plants, the chemical energy in the fossil fuels is transformed into heat energy and the heat energy is transformed into electrical energy. Hydroelectric energy This is mechanical energy of moving water. We can produce electrical energy using water falling from a reservoir or the tides of the sea. Biomass The chemical energy of organic waste from plants, like harvest leftovers, or from animals, like excrement, is used to generate heat energy or electrical energy. Uranium In nuclear power stations, energy from uranium, called nuclear energy, is transformed into heat energy and the heat energy is transformed into electrical energy.

5 Energy and the environment Using energy has made human progress possible. However, the production and use of energy have consequences on the environment. We call these consequences environmental impacts. Environmental impacts on the planet The end of out resources The atmosphere Some of the gases which vehicles release can react with the air and produce clouds of acidic substances. The rain from these clouds is called acid rain and it damages the soil, the harvests and the forests where it falls. The land We take rock from quarries and minerals from mines. By doing this, we also cause soil erosion. The oceans Oil spills from tankers leave dangerous substances in the sea. The waste from nuclear power plants also contaminates rivers and seas with radioactive substances, like uranium. Living things Aquatic organisms die because of industrial waste that is poured into rivers and seas and wind turbines kill birds. Most of the energy we use in the developed world comes from fossil fuels because they are cheap and easy to obtain. However, if we continue to increase our consumption of these fossil fuels, they Will run out very soon. This is why we need to control our consumption of fossil fuels and use other renewable sources of energy.

6 Sustainable development We know that excessive consumption of energy contaminates the environment and wastes natural resources. If we continue to use energy in this way, we may put future generations at risk. What can we do about it? Sustainable houses We can now build houses which need less energy and which use renewable natural resources. Hot water and heating The house has solar-thermal panels to heat the water. Electricity Solar-photovoltaic panels turn the energy from the sun into electrical energy and the wind turbine produces electricity from the wind. Water treatment This system collects rain water. Waste water from the house is also recycled and used to water the garden. Ecological swimming pool We don t need to change the water. It is cleaned naturally.

7 Taking care of our planet Our planet is also our home. We should all help reduce the energy we use in order to protect our natural resources and reduce our environmental impact and production of waste. Sustainable development improves our welfare and the welfare of developing countries by protecting our environment and our planet for future generations.

8 Energy-saving measures The authorities and the people that make up the general public are responsible for working together to save energy. It is important to remember that all our actions have consequences on our planet. What can people do? Use public transport whenever possible. Insulate the walls and Windows of buildings. Drive responsibly. Don t drive too fast and turn off the engine if the car is going to be stopped for more tan a few seconds. Use natural light when you can. Turn off lights when you are not using them. Use low-energy lightbulbs at home. Do not use heating or air conditioning too much. Keep the temperature at home at 21 ºC in winter and 26 ºC in summer. Choose the most efficient electrical appliances. They do the same work, but use less energy. Turn off appliances when you are not using them.

9 What can the authorities do? The authorities also have a series of obligations to help reduce energy consumption. To teach the society about the need to save energy, using publicity campaigns. To promote the use of renewable energies that allows us to produce clean energy. To make sure businesses take a responsible attitude towards the effects their production processes have on nature. To support investigation into alternative energy resources and the efficient use of energy.