Compare and contrast bio-mass and hydro electricity as sources of energy.

The waste material of living things and the dead parts of living things is called bio-mass. Bio-mass contains carbon compounds and it is the oldest source of heat energy for domestic purposes. The important examples of bio-mass being used as a fuel are wood, cattle dung and agriculture wastes like bagasse. Hydropower plants convert the potential energy of falling water into electricity. Water energy is a renewable source of electric energy, which will never get exhausted. The construction of dams on rivers helps in controlling floods and in irrigation.