Non-renewable resources

Non-renewable resources take a very long time to form, and cannot be replaced at the rate we use them.

Read that carefully. It does not say they are never formed again: coal is still forming somewhere, over millions of years. It says they cannot be replaced as fast as we use them.

So the difference between renewable and non-renewable is, again, about speed. Both come down to the same comparison: how fast Nature makes it, against how fast we take it.

The examples are fossil fuels (coal and petroleum) and minerals and metals like iron, copper and gold.

India has large coal reserves, and we mine coal to meet our growing need for energy.

But the book gives a number: "it has been estimated that the coal reserves in India may last another 50 years."

And demand is not standing still. It has been increasing as the population grows and building and development speed up.

So the conclusion follows: until more sustainable options are widely available, we need to use the coal we have judiciously. 'Judiciously' means with good judgement: not stopping, but not wasting either.