Hello, in the previous video, you looked at the rise of renewable energy. In this video, we're going to take a closer look at some of the most common renewable energy sources, sun, wind and water. We'll look at the technologies, how they produce energy, and look at the advantages and disadvantages of each one. Let's begin by looking at how we can get power from the sun. We call this solar power. The sun gives off energy in the form of heat. We can use something called a solar panel to turn that heat into energy. A solar panel is made up of lots of silicon cells joined together. Silicon, which has the chemical symbol Si, is a semiconductor. This means that it sometimes conducts electricity. The technology is quite complicated. But in simple terms, a solar panel is like a sandwich of two layers of silicon. The bottom layer does not have enough electrons, and the top layer has more than it needs. When photons, small particles of light from the sun, hit the silicon sandwich, they knock electrons from the bottom layer to the top. This creates electricity. Solar panels have many advantages compared to fossil fuels. They produce clean energy with very little waste that harms the environment. They can be installed on the tops of houses, so each home can be responsible for creating its own energy. After the solar panels have been installed, they save people money. Most importantly, any country in the world can used the power of the sun to create energy. So countries do not have to depend on other countries for their energy. There are two strong disadvantages, the cost of buying the solar panels and the fact that the sun does not shine all the time. Consequently, the panels either need an efficient way to store energy, or they need to be used with another power source. Second, let's talk about the power of wind. Modern windmills are called wind turbines. And many of them are placed together to create a wind farm. A turbine is a machine for producing power in which a wheel goes around. When the wind turns the blades of the wind turbine, it is connected to a shaft, which spins a generator and creates electricity Similar to solar power, wind power is a clean, naturally occurring energy that can be created wherever the wind blows. After the wind farm has been set up, it is easy and cheap to fix, and allows countries to create their own electricity without help from other countries. In contrast to solar power, it can be generated 24 hours a day because winds blow at night, too. However, there are a few disadvantages to wind power. A wind farm can be expensive to create, and some people believe that wind farms are unattractive to look at. Also, the best wind sites are not usually close to cities, which use the electricity, so the power often has to be transported a long way Third, let's look at water power. When we refer to energy created by water, we use the word hydro from Greek, so we call it hydroelectric power. Hydroelectric power is created by converting falling water into electricity. The process is similar to wind power. The water falls onto a turbine that spins a generator, creating electricity. Similar to solar and wind power, hydroelectric power is a clean energy with no waste product. The water is either used again or just continues flowing. The water also flows constantly, so like wind power it can produce electricity 24 hours a day. Also, since the flow of water can be controlled, more energy can be created at peak times, the times of day when people use more energy. There are a couple of disadvantages. The water has to fall a long way to create the force to turn the turbines. Therefore, you need to build a dam on a river to stop most of the water from flowing. This can be expensive to create, and it can cause problems for the land around the river, such as flooding. Also, people often need to leave their towns or farms when the dam is built. So in this video, we looked a little closer at three forms of renewable energy. Solar power from the sun, wind power, and hydroelectric power from water. We looked at the way that they work, and talked about some of the advantages and disadvantages of each.