In our previous chapter, we have learned about conventional sources of energy. We have also learned, if you are using conventional sources of energy, at an alarming rate, it will be getting exhausted. So people started to think, for an alternative, which we can use relatively for a longer period of time. After a study on this, human came up with non-conventional sources of energy. So what are the non-conventional sources of energy? Energy sources, which are based on advanced technologies are called non-conventional sources of energy. For example, nuclear energy, solar energy, etc Here, in this lesson let’s discuss about some of the non-conventional sources of energy. Let’s start with solar energy. As we know Sun is the main source of energy, for all living beings on the earth. Even the energy from the fossil fuel came from the Sun. Technologies are being developed to harness the massive amount of solar energy. Let’s discuss some application of solar energy. One of the most important application of harnessing solar energy is solar cooker. Solar cooker is very simple in design and mode of function. It is usually made of plain mirrors, plain mirrors are kept in, rectangular box. The light reflected from the plain mirror concentrates the solar energy, inside the solar cooker and generates enough heat to cook food. Another most important application of solar energy of harnessing solar energy, is solar cell. Solar cell is made of silicon. The solar panel convert the solar energy into electrical energy and stored it in a battery, for a later use. These are some of applications of solar energy, at the same time there are some limitations also. The technologies for harnessing solar energy are at an early stage. So, right now it is not cost-effective. Now we know, solar energy is a non-conventional sources of energy. It’s applications, it’s advantages and limitations. Another most common non-conventional sources of energy is, energy from ocean. Energy from ocean’s? What all are they? They are tidal energy, wave energy and ocean thermal energy. Let’s discuss them one by one. Let’s start with tidal energy. We all know tides happen near the seashore. Water rushes up near the seashore during a high tide and runs back during a low tide. Dams are build near the seashore to collect water during a, high tide. When the water runs back to the ocean, the kinetic energy of the flow of water is used to rotate the turbine to produce electricity. Another method of using energy from sea is, wave energy. Wave is a good source of energy, many devices are designed and tested to produce wave energy. For example, a holo tower. When the water gushes into the queue, the wave because of the wave it forces the air to move upwards. The kinetic energy of the air in the upward direction, is used in running the turbine. When the wave goes down the air also goes down which is also used in running the turbine to generate electricity. The next form of non-conventional sources of energy, which we can use from sea is, ocean thermal energy. The water at sea surface is hot during daytime, while the water at lower level is cold. This temperature difference can be used to generate energy. If the temperature difference is more than 20 degree celsius, we can utilize ocean thermal energy. For this, a volatile liquid like ammonia, is boiled using the heat of hot water at the surface. The steam produced by the volatile liquid is used to run the turbine to generate electricity. Here, in this lesson we have learned about non-conventional sources of energy and we have also learned, how we can harness non-conventional sources of energy.