What are renewable and non-renewable resources?

Two kinds of natural resources

Nature gives us everything we need: heat and light from the Sun, water from rivers, and food from plants and animals. But not every resource comes back once we use it. Natural resources are grouped into two kinds, depending on whether nature can renew them in a reasonable time.

Renewable resources

Remember the nellikai (Indian gooseberries) that Bhoomi and Surya collected? Ajji let them take only the fruits that had fallen on the ground, leaving enough for animals and birds. Seeds in the droppings of animals and birds grow into new trees, though it takes some years before those trees bear fruit. In this way, nature renews the forest.

Resources that get renewed, replenished or restored within a reasonable period of time are called renewable resources. Examples are air, water and forests. Even so, we must use them carefully: if we cut trees faster than new ones grow, or pollute water faster than nature can clean it, these resources will not last.

How nature renews water

Water is renewed through the water cycle you learnt about in the chapter on the states of water: the Sun’s heat evaporates water from seas, rivers and lakes, and it falls back as rain or snow, filling rivers, lakes and wells again. But polluted water does not become fit to use so easily, so we must keep it clean.

Non-renewable resources

Fossil fuels take millions of years to form. They are found in limited quantities, and once used, they are gone. Resources that are not produced or replenished within a reasonable time are called non-renewable resources. Examples are minerals, soil, rocks, coal, petroleum and natural gas. Soil and rocks are included because they take thousands to millions of years to form.

A closer look at fossil fuels

Different vehicles fill up with different fuels. Petrol and diesel are the most widely used. Petrol, diesel and kerosene are obtained from petroleum. Petroleum, natural gas and coal are called fossil fuels, because they formed from the remains of microorganisms and plants that were buried deep inside the Earth and changed over millions of years.

Fossil fuel	Main uses
Petroleum	Petrol and diesel for vehicles, kerosene
Natural gas	Cooking, electricity, CNG for vehicles
Coal	Producing electricity

Earlier, coal, wood and dung cakes were burnt for cooking; today, less polluting natural gas and LPG (Liquefied Petroleum Gas) have largely replaced them. CNG (Compressed Natural Gas) is a cleaner fuel than petrol or diesel.

Why we must save non-renewable resources

If we keep using fossil fuels as we do now, they will soon run out. Burning them also releases smoke and carbon dioxide, which pollute the air; in cities, vehicle smoke makes the air smell bad. So we should:

• walk or cycle to nearby places;
• use public transport;
• choose cleaner vehicles, such as those running on CNG, and electric vehicles, which give out no smoke;
• look for other sources of energy, such as the Sun and the wind.

Rocks and minerals, too, take thousands to millions of years to form, so they must be used responsibly. Learn practical ways to save every resource in how to conserve natural resources.