In a thermal power station, fuel like coal, naphtha, lignite, etc., are ignited. The heat energy liberated is used to convert water into steam at high pressure and temperature. Hence, thermal power plants use fossil fuels.The energy of the steam is used to rotate the turbine to generate electricity. 
The energy changes taking place here is:
Chemical energy -> Heat energy -> Mechanical energy -> Electrical energy. 

As there is no storage facility, there is no potential energy. The fast flowing stream of the river has kinetic energy. The turbine is used to convert the kinetic energy of the water directly into electrical energy.

Bio-gas is an excellent fuel as it contains up to 75% methane. It burns without smoke. Unlike wood, charcoal or coal it leaves no residue like ash. 

Solar energy is the primary source of energy for almost all the energy conversion.
Wind is caused by differences in the atmospheric pressure which is caused due to differential heating by sun light. When a difference in atmospheric pressure exists, air moves from the higher to the lower pressure area.

The kinetic energy possessed by huge waves near the seashore can be trapped to generate electricity. The waves are generated by strong winds blowing across the sea. A wide variety of devices have been developed to trap wave energy for rotation of turbine and production of electricity.
Hydrostatic energy is the energy possessed by static water i.e. potential energy 

The molten material mixed with gases in the mantle of the earth is called magma. It is a hot fluid material found below Earth's crust. When this magma reaches Earth's crust due to any crack in the crust or volcanoes, then we call it lava. Lave on cooling forms igneous rock.

Uranium is the primary element in nuclear reactors as it is capable of generating a large amount of energy by the process of nuclear fission.

The wind makes the rotor spin. As the rotor spins, the spinning of the blades gives power to a generator which produces electricity. So more the velocity of the wind, more will the blades spin and more will be the power generated.
The motion of the wind turning the turbine is called kinetic energy of the wind. This energy is converted into electricity.

Solar cookers achieve  higher temperature by using mirrors to focus the rays of the sun.
Concave mirrors are the most preferred ones as they can converge sunlight over a small area.