Tidal energy

Remember how the waves threw you around when you went swimming in the sea! Tidal power or tidal energy is the effect of the immense power of water. Tides are caused by the gravitational pull of the sun and the moon and the earth’s rotation. Tidal energy can be used to generate electricity. There are two major types of tidal energy-tidal stream system and tidal barrages. Tidal stream systems use the force of waves to power turbines. They cost little and are eco-friendly. Tidal barrages use the difference in height between high and low tide to generate energy. But building and maintaining barrage is expensive and is not eco-friendly.

 A tidal fence has an attached turbine. Water is forced to pass through the fence and the turbine. Tidal turbines are turned by the kinetic energy of the tides. But the force of the tides is so much that tidal turbines have to be made much stronger than wind turbines. This makes them more expensive.

 Biomass

Anything that is produced by a living organism or was once living is biomass. So, leaves and bark, leftovers of crops like paddy stalks and sugar cane, dead animals and cow dung are all biomass. The first discover by humans had been lit with biomass. Even today, millions of homes depend on biomass energy for cooking and heating.

 All living things take in energy to live and grow. Some of the energy is stored in their cells. When they die, this biomass can be used as bio fuel or agro fuel. Bio fuel can be solid, liquid or gaseous. Scientists are making new fuels like biodiesel and   ethanol from plants. There are cleaner than fossil fuels but they are still expensive.

 Advantages of using biomass

• Biomass is available top most of the people of the world and is practically free.
• Biogas plants are easy to operate, and not very expensive.

Disadvantages of using biomass

• Burning dung and wood products gases which pollute the environment
• Trees are cut for wood at a much faster rate than they are planted, therefore, one day there may be no biomass at all

Geothermal energy

`Geo’ means earth and `thermal’ comes from the Greek word therme, or heat. Geothermal is a renewable source of energy that comes from the earth. Although there is a huge amount of geothermal energy, it is about 20,000 times less than the amount of energy we get from the sun. Inside the earth, boiling magma and the natural decay of radioactive elements uranium and thorium release this energy. Just a few feet underground, the temperature is almost constant so the heat pump in a geothermal system uses this heat. Water heated by this heat energy produces steam. This steam can drive turbines to produce electricity.

Geothermal energy can be found even in Iceland! It is a reasonably clean form of energy since it does not release greenhouse gases. This form of energy is of low cost. Geothermal energy is, however, available only in some places since the rocks need to be hot enough. A certain type of rock is suitable for this, so we have to be careful where we drill. Sometimes, dangerous gases can be released.