Can Air, Water And Soil Be Exhausted By Human Activities?

We rely on a variety of materials to meet our daily needs. Some of these are readily available in nature, while others are created through human effort.

Materials obtained directly from nature, such as air, water, soil, and minerals, are referred to as natural resources.

Considering the availability of these natural resources, they can be broadly categorised into two main types:

1. Inexhaustible Natural Resources: These resources are found in unlimited quantities in nature and are not expected to be depleted by human activities. Examples include sunlight and air.
2. Exhaustible Natural Resources: The quantities of these resources in nature are finite. They can be used up and become unavailable due to human consumption. Examples include forests, wildlife, minerals, coal, petroleum, and natural gas.

A key question arises: Can we continue to use all natural resources indefinitely?

Exhaustible Natural Resources

As discussed, exhaustible natural resources are limited in supply and risk depletion from human activities. The concept of exhaustibility can be illustrated by considering how different generations might consume a finite resource. If earlier generations consume a resource excessively without regard for future availability, later generations may face scarcity or complete absence of that resource.

This highlights the importance of judicious use and conservation of exhaustible resources.

In this chapter, we will focus on some specific exhaustible natural resources: coal, petroleum, and natural gas.

These resources are formed from the remains of ancient living organisms that died millions of years ago. Because they originate from fossils (dead remains), they are collectively known as fossil fuels.

Coal

Coal is a well-known material, often seen or heard about. It is a substance that is typically hard like stone and is black in colour.

Historically, coal has been used for various purposes. It serves as a fuel for cooking food. In the past, it powered railway engines by producing steam. Today, it is extensively used in thermal power plants to generate electricity and also as a fuel in numerous industries.

Story Of Coal

Coal was formed over vast periods, approximately 300 million years ago. During that time, the Earth had dense forests located in low-lying, wet areas.

Through natural events, such as floods, these forests were gradually buried under soil. As more layers of soil accumulated over them, the buried vegetation was subjected to intense compression.

With increasing depth, the temperature also rose. Under these conditions of high pressure and high temperature, the dead plant matter underwent a very slow conversion process, eventually turning into coal.

Since coal is primarily composed of carbon, this gradual transformation of dead vegetation into coal is termed carbonisation.

Because coal originated from the remains of ancient plant life, it is classified as a fossil fuel.

When coal is burned in the presence of air, it mostly produces carbon dioxide gas.

In industrial settings, coal is processed to yield several useful products, including coke, coal tar, and coal gas.

Coke

Coke is a by-product of coal processing. It is characterised by being a tough, porous, and black substance. It is considered an almost pure form of carbon.

Coke is mainly used in the manufacturing of steel and in the process of extracting various metals from their ores.

Coal Tar

Coal tar is obtained during the processing of coal. It is a black, thick liquid with a strong, unpleasant odour.

Coal tar is not a single substance but a mixture of around 200 different substances. Many useful materials used in daily life and industry are derived from the products obtained from coal tar. These include starting materials for making synthetic dyes, various drugs, explosives, perfumes, plastics, paints, photographic materials, and roofing materials.

An interesting example is naphthalene balls, used to repel insects like moths, which are also produced from coal tar.

Historically, coal tar was used for metalling roads, but today, a petroleum product called bitumen is commonly used for this purpose.

Coal Gas

Coal gas is another product obtained when coal is processed to produce coke. It is used as a fuel in various industries, particularly those located close to coal processing plants.

In the early 19th century (around 1810 in London and 1820 in New York), coal gas was used for street lighting. While it can produce light, its primary use nowadays is as a source of heat.

Petroleum

Many light vehicles such as motorcycles, scooters, and cars use petrol as fuel, while heavy vehicles like trucks and tractors run on diesel. Both petrol and diesel are derived from a natural resource known as petroleum.

The name "petroleum" originates from the Latin words 'petra' (meaning rock) and 'oleum' (meaning oil), indicating that it is oil extracted from between rocks beneath the Earth's surface.

Petroleum was formed from the remains of tiny organisms that lived in ancient seas. After these organisms died, their bodies settled on the seabed and were covered by layers of sand and clay over millions of years.

Under conditions of absence of air, high temperature, and high pressure, the buried remains of these marine organisms were slowly converted into petroleum and natural gas over millions of years.

Observing typical deposits, one finds that the layer containing petroleum oil and natural gas is situated above the layer of water. This arrangement occurs because oil and gas are less dense (lighter) than water and do not mix with it.

The first oil well in the world was drilled in Pennsylvania, USA, in 1859. In India, oil was first discovered at Makum in Assam in 1867. Significant oil reserves in India are found in Assam, Gujarat, Mumbai High, and in the river basins of Godavari and Krishna.

Refining Of Petroleum

Crude petroleum, as extracted from the earth, is a dark, oily liquid with an unpleasant smell. It is a complex mixture comprising various useful substances, including petroleum gas, petrol, diesel, kerosene, lubricating oil, paraffin wax, and bitumen.

The process of separating these different components or fractions of petroleum is called refining. Refining takes place in a specialised facility known as a petroleum refinery.

Here are some of the various constituents obtained from petroleum and their common uses:

Constituent of Petroleum	Uses
Petroleum Gas in Liquid form (LPG)	Fuel for homes and industries (cooking gas)
Petrol	Fuel for motor vehicles and aviation, used as a solvent in dry cleaning
Kerosene	Fuel for stoves, lamps, and jet aircraft engines
Diesel	Fuel for heavy motor vehicles and electric generators
Lubricating oil	Used for lubrication of machinery parts
Paraffin wax	Used in ointments, candles, petroleum jelly (vaseline), etc.
Bitumen	Used in paints and for surfacing roads

Many valuable substances are derived from petroleum and natural gas. These are collectively termed 'Petrochemicals'. They are essential in manufacturing detergents, synthetic fibres (like polyester, nylon, and acrylic), polyethylene, and other types of plastics.

Hydrogen gas, which can be obtained from natural gas, is used in producing fertilisers like urea.

Given its immense commercial value and wide range of applications, petroleum is also commonly referred to as 'black gold'.

Natural Gas

Natural gas is a highly important fossil fuel, valued for its ease of transportation through pipelines. It is often stored under high pressure as Compressed Natural Gas (CNG).

CNG is increasingly used for electricity generation and, notably, as a fuel for vehicles because it is significantly less polluting than petrol or diesel, making it a cleaner fuel option.

A major advantage of natural gas is that it can be supplied directly via pipelines for burning in homes and factories. Pipeline networks for natural gas supply exist in places like Vadodara (Gujarat), parts of Delhi, and other locations.

Natural gas also serves as a raw material for producing various chemicals and fertilisers.

India possesses substantial reserves of natural gas, with deposits found in Tripura, Rajasthan, Maharashtra, and the Krishna Godavari delta region.

Some Natural Resources Are Limited

As established at the beginning of this chapter, certain natural resources, including fossil fuels (coal, petroleum, natural gas), forests, and minerals, are exhaustible.

The formation of coal and petroleum from dead organic matter was an extremely slow process, taking millions of years under specific geological conditions. In contrast, the currently known reserves of these fossil fuels are estimated to last for only a few hundred years at present consumption rates.

Furthermore, burning these fuels contributes significantly to air pollution and is a major factor linked to global warming (the increase in the Earth's average temperature).

Considering their limited supply and environmental impact, it is crucial to use these fossil fuels only when absolutely necessary and with careful planning. This approach helps to:

• Create a better environment by reducing pollution.
• Minimise the risk of global warming.
• Ensure the availability of these resources for a longer duration for future generations.

It is important to understand that creating fossil fuels like coal, petroleum, and natural gas in a laboratory from dead organisms is not possible. Their formation requires immense periods and specific geological conditions (high pressure, high temperature, absence of air) that cannot be replicated in a laboratory setting.

Organisations like the Petroleum Conservation Research Association (PCRA) in India provide advice on how to conserve petrol and diesel while driving. Their recommendations typically include:

• Driving at a steady and moderate speed whenever possible.
• Turning off the engine while waiting at traffic lights or other stationary points.
• Maintaining the correct tyre pressure in vehicles.
• Ensuring regular maintenance of the vehicle to ensure optimal performance and fuel efficiency.

Adopting such practices contributes to fuel conservation and reduces environmental impact.

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