Nuclear energy

Nuclear energy is the result of nuclear fission. In a nuclear fission, the nucleus of a heavy atom like uranium or plutonium splits into two lighter elements. The sum of the masses of the products is lower that the reactant atom. This small difference in mass gets converted to energy as per the following equation:

E= MC2

Here ?M? stands for the difference in the mass of the original atom and its products, ?C? is the speed of light in a vacuum. This formula was first derived by Albert Einstein in 1905.

Nuclear reactors generate nuclear energy. A nuclear reactor is a complex equipment where neutrons bombard the atoms of uranium. As a result, the atoms of uranium split into two lighter elements- Krypton and boron. Along with the lighter elements, three neutrons are also produced. The neutrons set up a self-perpetuating reaction, and the reactor is said to have gone critical. This reaction can be controlled using a boron rod and a steady state of fission is established. The energy produced by the fission reaction is used to produce steam, which is then used to drive a turbine, thus producing electricity.

The biggest advantage of nuclear power is that a single atom of uranium can produce an immense amount of energy. The energy produced from one atom of uranium is equal to that from 100 million atoms of carbon. ?One atomic mass unit of uranium can produce more than 900 electron megavolts (eMV) of electricity. Thus, nuclear energy has emerged as a very attractive source of energy.

Presently, nuclear power plants are located in Tarapur, Kalpakam, Rana Pratap Sagar (Rajasthan), Narora (UP), Kakrapar (Gujarat) and Kaiga (Karnataka). The total installed capacity of nuclear energy in India contributes to less than 3% of the energy requirement of the country. In contrast, some countries source nearly 30% of their energy need from nuclear power. Many reactors have been planned to increase the share of nuclear power in power generation in India.

However, nuclear energy is not easy to harness. The biggest problem with nuclear power is the storage and disposal of nuclear waste. Used uranium produces harmful radiation for many years. Therefore, used fuel needs to be stored and disposed properly. The second major problem is with security. Long before being used for power generation, nuclear power was used for destructive purposes- Japan was attacked with nuclear bombs World War II. Used uranium can be used to make atomic bombs. Therefore, stringent standards are required to ensure the safety of the used fuel.

Setting up a nuclear energy plant requires a huge investment. The technology is expensive, and there are safety issues involved. Due to the fear of accidental leakage, there is a lot of unrest in local communities over proposed nuclear plants.

Investment in research will improve the safety of nuclear energy plants and may allow setting up of more nuclear plants. Increased share of nuclear energy will ultimately help feed the immense appetite for energy in the country.

Click this link for more articles on class 10 science.

Click here for CBSE books.

Wind energy

Man has used the power of the wind for hundreds of years. The earliest seafarers used wind energy to power the ships. We used to use windmills to grind wheat, rice and corn. Now we use windmills to generate electricity. Even, some of our leisure activities like flying a kite also requires wind energy.

If you travel along the southern coast of India, you will see thousands of windmills, which harness the wind energy and convert it into electricity. So how do windmills produce electricity?

The wind has kinetic energy. The blades of the windmill rotate when the wind strikes it. The turbine is connected to the blades converts the kinetic energy of the wind into electric energy. When a magnetic coil rotates around a metal core, it produces electricity. The rotatory movements of the blades rotate a magnetic coil within the turbine to produce electricity. The amount of electricity produced is proportional to the speed of the wind. ?As the electricity produced by a single windmill is small, thousands of windmills are installed where land and wind conditions are favourable, these are called as wind energy farms or simply wind farms. The largest such farm in India is in Kanyakumari District in Tamil Nadu. This farm produces 380 MW of electricity.

Wind energy is one of the clean sources of energy. It is renewable, does not pollute the environment and will be a source of energy for as long as the winds blow. Wind energy can generate nearly 45,000 MW of electricity in India. Due to the concerns about global warming, many countries are focussing on the wind as a source of energy. Denmark is one such country. Nearly 1/4th the energy requirement of Denmark is met through wind power.

The initial costs of setting up a wind farm are high. A 1 MW farm requires about 2 hectares of land. Also, windmills can only come up in areas with wind flow throughout the year. The wind speed should be excess of 15 km/h.

Apart from these, batteries are required to store the energy produced by the wind and then there are maintenance costs. Therefore, wind energy is still a fledgling enterprise. However, once set up, the running costs are fairly low. As the initial investment is high, governments offer subsidies to help promote the wind as a source of energy.

With the improvement in the design and efficiency of the wind turbines, this source of energy may one day be truly affordable without the need for subsidies.

Click this link for more articles on class 10 science.

Click here for CBSE books.

Solar energy

Man has been using solar energy for many thousands of years. We use solar energy to dry our clothes and food. In fact, the sun plays a critical role in our culture as well. Most communities in India worship the sun. Mythological and religious texts refer to the sun. So, what makes the sun so important?

The sun is the source of all energy in the world. It provides us with light, heat and enables the plants to produce food. It is also responsible for the formation of winds, clouds, and rain. Therefore, it would not be incorrect to say that life on earth would not be possible without the sun.

We in India are lucky because most parts of our country receive abundant sunlight throughout the year. We have been using solar energy to heat up water and to cook food. However, sunlight can only be used during the daytime. Also, if the sky is cloudy, then the amount of solar energy reaching the surface of Earth is much lower.

To rectify this problem, we have developed solar cells. These cells are designed to convert solar power into electricity that we can store for future use. The solar cells are made up of silicon, a mineral found in abundance in the earth?s crust. A single cell will develop a voltage of 0.5 t 1V and can produce about 0.7 Watts of power when exposed to sunlight. As the amount of power generated by a single cell is low, many cells are combined to form a solar panel.

Solar energy has many advantages. It is nearly a limitless source of energy. The sun has been shining for the past 5 billion years, and it is likely to shine for many millions of years. It is renewable and most importantly, it is the cleanest source of energy.

However, solar energy is not without its disadvantages. As the output from a single solar cell is quite small, many millions of cells are required to be assembled to produce enough power. Therefore, large tracts of land are needed to install these panels. In remote, sparsely inhabited areas (like Leh or Rajasthan), it may be possible to get large tracts of lands, but laying transmission lines is expensive in these areas. An innovative solution is to install these panels over irrigation canals. Installation of solar panels over irrigation canals has two advantages- there is no need to use fertile farmland and the solar panels minimise water loss due to evaporation.

Manufacture of solar panels requires Silicon, a mineral abundant in the earth. However, extracting and refining it is expensive. Production of solar panels also requires silver, a rare and precious metal. Therefore, the cost of installation of solar panels is quite high, but the running costs of negligible.

With the improvement in technology, the cost of solar energy is steadily coming down. As awareness increases, it is likely that the use of solar energy will increase. We can reduce our dependence on fossil fuels by increasing the use of solar energy.

Click this link for more articles on class 10 science.

Click here for CBSE books.

Fossil fuels- advantages and disadvantages

In our previous article, we had discussed the nature of fossil fuels. In this article, we shall discuss the advantages and disadvantages of fossil fuels.

The world is overwhelmingly dependent on fossil fuels for its energy requirements. Coal is the predominant fuel used in our factories and power plants. Almost all our transport runs on oil. In fact, we are so dependent on fossil fuels that we cannot imagine our life without them.

Fossil fuels have some distinct advantages that make them a preferable source of energy. The amount of energy produced by burning of fossil fuels is quite high. Also, fossil fuels are easily available, especially in countries that have deposits of these fuels. It is, therefore, not surprising that we are so dependent on them for our energy needs.

However, there are many disadvantages of using fossil fuels. These fuels are a finite resource. Fossil fuels were formed millions of ago and will take many years to replenish. Therefore, we have to use them with prudence. Also, fossil fuels are a dirty source of energy. Burning of fossil fuels produces carbon dioxide that is the major greenhouse gas in the atmosphere. ?Indiscriminate burning of fossil fuels has led to a rapid rise in world temperature due to the greenhouse effect produced by carbon dioxide. Also to carbon dioxide, burning of fossil fuels produce oxides of sulphur and nitrogen. These cause air pollution and lead to the formation of acid rain that is harmful to plants and animals. These pollutants also increase the risk of allergic and respiratory disorders in humans.

Apart from producing carbon dioxide and oxides of nitrogen and sulphur, burning of coal also produces a fine ash called as fly ash. This fly ash coats the surface of buildings and fields, especially in the vicinity of power plants. Fly ash causes damage to buildings and impairs production of food crops. Most power plants store this fly ash in ponds called as ash ponds. A few years ago, there was a breach in one of the ponds and acres of fertile farmland were cover with fly ash, rendering these lands unfit for cultivation.

Most of our vehicles burn oil for energy. Burning of oil also produces carbon dioxide and oxides of sulphur and nitrogen. Also, engines also produce small particulate matter that remain suspended in air. This particulate matter is particularly harmful, and this is the reason respiratory illness is higher in highly polluted cities like New Delhi and Beijing.

Mining of fossil fuels also leads to environmental degradation. Forests are cut down to mine these fuels. Seas and oceans are the most abundant source of oil. We have to dig deep wells in the seabed to extract this oil. In this process when there is an oil leak, millions of square kilometres of the ocean surface is covered with this oil, leading to an environmental disaster like the one that happened in Gulf of Mexico.

Excessive use of fossil fuels also has an economic impact, especially in countries that no not have adequate reserves. India imports nearly 3/4th its requirement of oil. Paying for this contributes the maximum to our trade deficit and puts a huge strain on our economy.

Therefore, we should use fossil fuels with care. We can reduce our dependence on fossil fuels by cutting down the wasteful expenditure of energy and by using other alternative sources of energy like hydroelectric power or nuclear power.

Click this link for more articles on class 10 science.

Click here for CBSE books.

Fossil Fuel

Coal, oil, and natural gas are the most commonly used sources of energy. These are all hydrocarbon based and known as fossil fuel. Fossil fuel is a generic term used to describe organic geological deposits that are combustible. Fossil fuels are formed from decaying plant and animal matter that under the influence of heat and pressure, is converted into coal, oil and natural gas.

Many million years ago, most of the land on earth consisted of swamps and oceans. Many huge trees and other leafy plants grew in these swamps. The surface of oceans was covered by millions of algae, which are very small plants. As these plants and algae died, they sunk to the bottom of swamps and oceans. Over a period, this layer of organic matter was covered by sand, clay and other minerals. As the weight of the layer of sand and clay increased, water was squeezed out of organic matter and eventually fossil fuels were produced. This period is called as carboniferous period and it is estimated to have occurred some 300 million years ago.

Coal is a black coloured, rock-like substance. It is made up of carbon, oxygen, nitrogen, sulphur and hydrogen. There are three major types of coal-anthracite, bituminous and lignite. Anthracite has the highest proportion of carbon and is the hardest of the three types of coal. Lignite has the least amount of carbon and is the softest of the three types of coal. Coal is mined from the earth in many different ways. Coal is mined from deep vertical shafts dug into the earth. These mines are called as closed mines. Coal can also be mined by stripping away the top layer of sand and clay above the coal. These mines are called as open mines. Once mined, coal is transported by trains, ships and even through pipelines to distant places where it is used in industry or is used to generate electricity.

Oil is a thick, sticky liquid which has many uses in our life. Sumerians were the first to use petroleum. They used it for medicinal purposes and lighting lamps. Currently, oil is used for transportation, industry and as a raw material for many substances like fertilisers. Oil is found deep in the crust of the earth, between two layers of rocks. Rigs drilled into the crust of the earth?extract oil. Once extracted, this oil is fractionated or refined into its many components- petrol, diesel, natural gas and fuel oil. The waste left over after refining is called pitch and is used to lay roads. Today, oil is found in most countries, but USA, Russia and the countries in the Middle East are the largest producers of oil.

Natural gas is another hydrocarbon based fossil fuel that we commonly use. Natural gas is found in close vicinity to oil and both are extracted together. Natural gas is lighter than air and is colourless and odourless. The primary component of natural gas is methane that consists of one carbon molecule attached to four hydrogen atoms (CH4).

Fossil fuels have been made over millions of years. And they are a finite resource. Once exhausted, it will take millions of years to replenish. Therefore, it is important to conserve them. We can save fossil fuels by cutting down on the wasteful expenditure of energy and by investment in technology that improves efficiency.

Click this link for more articles on class 10 science.

Click here for CBSE books.

Sources of energy

From the moment we wake up, to the time we sleep, we use energy. We use electricity to heat water for bathing, use gas to cook breakfast and go to school in vehicles powered by petrol or diesel. Electricity, gas, and petrol are all sources of energy.

Sources of energy are classified in different ways. Since times immemorial, man has used wood to produce energy. Then coal was discovered. The widespread use of coal led to the industrial revolution and improved the lives of millions of people. Then came petroleum that enabled the development of mechanised transport. Wood, coal and oil are all called conventional sources of energy. Since they were produced millions of years ago from the fossilisation of organic matter, they are also called as fossil fuels. Fossil fuels are the most common source of energy in the world. They account for nearly 3/4th of the energy requirement of the world. However, this source of energy is a finite resource. If we indiscriminately use fossil fuels, then we will soon run out and stare at a crisis.

To reduce dependence on fossil fuels, man has been developing newer sources of energy. The earliest source was flowing water. The kinetic energy of flowing water can be harnessed to produce energy. Dams store water from rivers, which then flows through pipes producing electricity from the kinetic energy of flowing water. Power produced from water is also known as hydroelectric power. ?Similarly, we have harnessed the power of wind to generate energy. These sources of energy are called non-conventional energy. Some other non-conventional sources of energy include solar power, geothermal energy, nuclear energy and tidal energy. However, these are only a minor source of energy.

Energy is also classified on whether it is renewable or non-renewable. We can produce energy from sunlight as long as the sun shines. Similarly, as long as the wind continues to blow and rivers continue to flow, we can harness their energy for our use. These are called renewable sources of energy. However, fossil fuels are a limited in availability. Also, these will take many millions of years to renew. Therefore, fossil fuels are called as non-renewable energy.

We have all seen cow dung being used as a source of energy. Similarly, we have also seen firewood being used for cooking in villages. As these are procured from living beings, these are called biomass energy. Although a renewable source, they have low efficiency and produce a lot of smoke. With the improvement in technology, it is now possible to produce gas from biomass. As cow dung is the predominant ingredient, this is also called as ?gobar-gas?.

Based on the above, what would you consider a good source of energy?

A good source of energy should have high efficiency, must not produce a lot of smoke, should be easily available, should be renewable and should not require complicated technology to use. The current sources of energy do not?satisfy all these criteria. Therefore, man is always working to find newer sources of energy which will meet all the criteria.

Click this link for more articles on class 10 science.

Click here for CBSE books.


What is energy? The Basics.

Pedaling a bicycle requires energy, so does walking. What about your car? It also requires power to move, the power that comes from burning of gasoline. So, energy is associated with an activity. But this is not only action or movement visible to the naked eye. The action that happens at the level of individual cells and atoms also require energy. Therefore, energy is essential for life, as movement is a pre-requisite for life.

How many of you cycle to school? Have you ever wondered how the pedaling action of your legs propels the cycle forward? Pedaling converts the chemical power in muscles to the kinetic force, ?Which helps move the cycle forward. In a car, the power stored in gasoline is used to move the vehicle.

Thus, you note that there are two types of energy. The first type is the storage form or potential energy. The second type is the one that makes motion possible- kinetic force.

Any stored energy is called potential energy. It can be chemical, nuclear, gravitational or mechanical in nature.? On the other hand, the energy found in moving objects is called kinetic energy. A bicycle that moves forward has kinetic force, so does an automobile, train, and airplane. Even the tiniest atoms possess kinetic energy as the electrons are always moving around the nucleus. The sound is another example of kinetic power.

We have learned before that energy is neither created nor destroyed. If this is true, then the world should not face a crisis, right?? Right and wrong.

It is true that energy is neither created nor destroyed. It can only transform from one form to another. But what happens when a candle burns? Apart from producing light, it also produces heat that is lost in the environment. This heat cannot be captured to produce wax. Similarly, a pan of hot water left at room temperature will lose heat and come down to room temperature. So where has the heat gone? The potential energy stored in the water has dissipated in the air as kinetic energy. Therefore, you see that the transformation of energy is an extremely inefficient process. Even the best of machines and power plants waste over 50% ?during conversion. As there is a loss of energy into forms that cannot be used by us, if we keep using fuel indiscriminately, then our sources of energy would soon run out. We would then be staring at a crisis.

Thus, to summarize, energy is essential for life. There are two principal forms- potential and kinetic force. Energy is neither created nor destroyed, but it can transform from one form to another. But this process of transformation is far from efficient. Therefore, we need to conserve our sources of energy. Otherwise, we will be facing a crisis in future.

Click this link for more articles on class 10 science.

Click here for CBSE books.