Friday, December 22. 2017What is solar energy?
The Sun covers our planet in light and warmth. A mixture of heat and light from the Sun can be used as energy to heat water and make machines work. Energy from the Sun is called solar energy. Solar means to do with the Sun. The Sun is a blazing star. This huge burning ball of gas is our nearest star. Even though it is 150 million km away from Earth, the Sun can shine so brightly that you need to shade your eyes from its light. Sunlight can feel hot on your skin. You need to wear sun cream to protect your skin.
Energy makes things work. You need energy to throw a ball. Without energy, nothing works. Everything needs energy. There are many types of energy. The Sun’s energy helps plants and flowers to grow. We eat plants and other foods. The energy from food gives us the energy to throw a ball and run around.
The Sun’s heat dries wet clothes. The Sun is packed with energy. In one hour, the Earth receives more energy from the Sun than the whole world uses in a year. This energy can also be used to generate electricity. We call this electricity solar power. Friday, December 22. 2017Heat from the SunWhat happens to the water in a paddling pool on a sunny day? The Sun makes it warm enough to lie in without shivering. This energy from the Sun can heat the water for hot baths and showers. Heat from the Sun can be used to heat houses too.
Sunlight shines through glass in this greenhouse. Fruits such as tomatoes and exotic plants grow well in a hot greenhouse. The Sun’s light and heat pass through the clear glass windows. When the light and heat are trapped inside the greenhouse, it feels very warm.
The Sun can be used to heat up water. Buildings can be fitted with pipes and plates that collect the Sun’s heat on the roof. These contain a liquid that heats up quickly when the Sun shines on it. The hot liquid is used to heat water. The hot water is sent through pipes to taps, ready for use.
Some colours soak up the Sun’s heat better than others. Paint some paper plate’s different colours, including one black and one white. Put them out in the sunshine for a few hours, and then check which one is hottest, and which one is coolest. Black clothes absorb the Sun’s heat and make you feel even hotter. Solar pipes and plates are black so that they soak up lots of heat. Friday, December 22. 2017Electricity from the Sun’s energy
The Sun’s energy can be used to make heat and electricity. Special mirrors gather the Sun’s energy. This energy creates heat. The heat is used to turn water into steam. Steam is used to produce electricity.
Mirrors collect sunlight. Mirrors concentrate sunlight in one place. In a solar power tower, lots of mirrors reflect sunlight onto a special collector. The collector is filled with a liquid. The liquid stays hot for a long time. It is pumped into containers. When power is needed, the liquid flows to a heat exchanger where it heats water and produces steam. The steam turns a turbine that makes electrical energy.
These curved mirrors turn to follow the Sun. Power troughs have mirrored surfaces. They turn to follow the Sun. Sunlight heats a liquid-filled pipe in the centre of the troughs. This is sent to a heat exchanger. The steam produced is used to create electricity.
Steam from hot water turns a turbine. Sunlight is used to boil a liquid that heats up quickly. Steam from the boiling liquid powers a turbine. A turbine is like a water-wheel which is powered by steam instead of water. The turbine drives a generator which produces electricity for homes, offices and factories. |
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