Hydroelectricity is generated by fast flowing water. A wall is constructed across a river and water is held back in a lake. The water is then made to fall over the wall from a height, the force of which helps to produce electricity.
Hydroelectricity is a renewable resource pollution free and an environment-friendly source of power. Thermal electricity which is generated by burning of coal causes pollution, is non-renewable and is not environment friendly.

Minerals are natural resources which are obtained from rocks. Geologists define a mineral as a "homogeneous, naturally occurring substance with a definable internal structure." They are normally found in solid, liquid and gaseous states. They have a definite chemical composition and crystalline structure. A particular mineral that will be formed from a single or certain combination of elements depends upon the physical and chemical conditions under which the material forms. Minerals are classified into metallic and non-metallic minerals and energy resources.
(a) Metals are obtained from metallic minerals. They are further subdivided into:
   (i) Ferrous minerals containing iron, e.g. iron-ore, manganese, nickel, cobalt, etc.
   (ii) Non-ferrous minerals, e.g.copper, lead, tin, bauxite, etc. that do not contain iron.
   (iii) Precious minerals, e.g. gold, silver, platinum.
(b) Non-metals, e.g. mica, salt, potash, sulphur, granite, limestone, dolamite, gypsum, marble, etc. lack the lustre and hardness of metals.
(c) Energy minerals are fossil fuels, e.g. coal, petroleum, natural gas and are used to generate energy.

(a)High risk involved
(b)Due to poisonous fumes, mines are vulnerable to workers for pulmonary diseases.
(c)Risk of collapsing mines roofs, and fires in coal mines.
(d)Water sources get contaminated

Nuclear Power plant
(a) Naraura: Uttar Pradesh
(b) Kalpakkam: Tamil Nadu
(c) Kaiga: Karnataka
(d) Rawat Bhata: Rajasthan

Thermal power plant
(a) Namrup: Assam
(b) Tuticorin: Tamil Nadu

Kudremukh mines are located in Bellary-Chitradurga-Chikkamagaluru Tumakuru iron-ore belt.

Certain minerals may occur as alluvial deposits in the sands of the valley floors and the base of hills. These deposits are called 'placer deposits'

Magnesium is largely derived from the ocean water.

The Peninsular plateau region, especially the Damodar Valley Region of Jharkhand and West Bengal, the Son, Mahanadi, Godavari and Wardha Valleys of Madhya Pradesh, Chhattisgarh, Odisha, Maharashtra and Andhra Pradesh have rich deposits of Gondwana coal. In the north-eastern states of Meghalaya, Assam, Arunachal Pradesh and Nagaland, tertiary coal is found. In Tamil Nadu, lignite deposits are found. The three major forms of coal are Anthracite, Bituminous and Lignite. Anthracite is the highest quality of coal with more than 80 per cent carbon content and very low moisture content. It is hard, compact and deep-black in colour. It is found in the Jharia coalfields of Jharkhand in a small quantity. Bituminous is the most widely used coal. High grade bituminous coal is used in metallurgical industries, especially for melting iron in blast furnaces. So it is also known as metallurgical coal. Bituminous coal contains 60 to 80 per cent carbon, low moisture, and has high heating capacity. It is formed when coal has been buried deep and subjected to increased temperatures. It is found in large quantities in the Jharia coalfield, of Jharkhand and Raniganj coalfield of West Bengal. Lignite contains about 60 per cent carbon and has high moisture content. It is a low grade brown coal which is soft and has low heating capacity. It is used in thermal power stations. Principal reserves are found in Neyveli in Tamil Nadu.