Geothermal and Nuclear Energy

Geothermal Energy Geothermal energy, sourced from hot springs, has

been used for bathing since Paleolithic times and for heating during the Roman era.

However, now it is now better known for electricity generation.

Worldwide, about 10,715 megawatts (MW) of geothermal power is online in 24 countries.

An additional 28 Gigawatts of direct geothermal heating capacity is installed for district heating, space heating, spas, industrial processes, desalination and agricultural applications

What exactly is geothermal energy?

Geothermal energy is the thermal energy generated and stored in the

Earth.

Earth's geothermal energy originates from the original formation of the planet (20%) and from radioactive

decay of minerals (80%)

Geothermal power plants use the heat obtained from the earth’s thermal

energy 

Inside a geothermal plant, the heat energy is used to heat water into water vapour and that rotates turbines, thus

generating electricity

Recent research in Geothermal Energy

Geothermal energy is increasingly contributing to the power supply world wide.

Iceland is the world-leader in expanding development of geothermal utilization: in

recent years the annual power supply here doubled to more than 500 MW alone in the

supply of electricity. 

Alone in the region of Travale, in Italy, a team of European scientists have found geothermal reservoirs, holding a potential comparable to the effectiveness of 1000 wind power plants. 

In Germany also, development is taking place in the field of geothermal energy. Here,100

MW of power is currently being provided through geothermal energy.  

Advantages and Disadvantages of

Geothermal energy

AdvantagesGeothermal energy generally

involves low running costs since it saves 80% costs over fossil fuels and no fuel is used to

generate the power. 

The main advantages of using geothermal energy is that it does

not create any pollution. It has helped in reducing global warming and pollution. 

Governments of various countries are investing hugely in creation of geothermal energy which on

the other hand has created more jobs for the local people.

DisadvantagesGeothermal sites can run out of steam over a period of time due to drop in temperature or if too

much water is injected to cool the rocks.

Since this type of energy is not widely used, the unavailability of equipment, staff, infrastructure, training pose hindrance to the

installation of geothermal plants across the globe.

Geothermal sites may contain some poisonous gases which can

escape deep within the earth, through the holes drilled by the

constructors.

Nuclear power is the use of

sustained nuclear fission to

generate heat and electricity.

Nuclear energy provides about 6% of the world's energy and 13–14% of

the world's electricity.

In 2007, the IAEA reported

there were 439 nuclear

power reactors in operation in

the world,

operating in 31 countries.

Nuclear Power

Nuclear power is the use of

sustained nuclear fission to

generate heat and electricity.

Nuclear energy provides about 6% of the world's energy and 13–14% of

the world's electricity.

In 2007, the IAEA reported

there were 439 nuclear

power reactors in operation in

the world,

operating in 31 countries.

Nuclear reaction is the process in which two nuclei, or else a nucleus of an atom and a subatomic particle (such as a proton, neutron, or high energy electron) from outside the atom, collide to produce products different from the initial particles. The energy released in the nuclear reaction is called nuclear energy or atomic energy.

Nuclear energy is produced naturally and in man-made operations under human control.Naturally: Some nuclear energy is produced naturally. For example, the Sun and other stars make heat and light by nuclear reactions

Man-Made: Nuclear energy can be man-made too. Machines called nuclear reactors, parts of nuclear power plants, provide electricity for many cities. Man-made nuclear reactions also occur in the explosion of atomic and hydrogen bombs.

Nuclear energy is produced in two different ways, in one, large nuclei are split to release energy. In the other method, small nuclei are combined to release energy.

Nuclear fission is a nuclear reaction in which the nucleus of an atom splits into smaller parts, often producing two or three free neutrons and photons  and mass of original atom is converted into large amount of energy, and releasing a very large amount of energy, in accordance with the equation E = mc2

Nuclear Fission

Nuclear fission produces energy for nuclear power and to drive the explosion of nuclear weapons. In a nuclear weapon, there is uncontrolled nuclear fission, while in a reactor, the fission is always monitored.

FISSILE ISOTOPESFissile isotopes are isotopes of an element that can be split through fission. Only certain isotopes of certain elements are fissile. For example, 239Pu and 232Th. One isotope of uranium, 235U, is fissile, while another isotope, 238U, is not fissile. SPLITTING OF URANIUM

Uranium is the principle element used in nuclear reactors and in certain types of atomic bombs. The specific isotope used is 235U. When a stray neutron strikes a 235U nucleus, it is at first absorbed into it. This creates 236U. 236U is unstable and this causes the atom to fission. The fissioning of 236U can produce over twenty different products. However, the products' masses always add up to 236. The following two equations are examples of the different products that can be produced when 235U fissions:

235U + 1 neutron 2 neutrons + 92Kr + 142Ba + ENERGY 235U + 1 neutron 2 neutrons + 92Sr + 140Xe + ENERGY

Nuclear Fusion

Fusion is a nuclear process in which two light nuclei combine to form a single heavier nucleus.

A large amount of energy is released in fusion reactions. However, though fusion is an energetically favourable reaction, it does not occur under standard conditions here on Earth because of the large energy requirement.

Fusion reactions have been going on for billions of years in our universe. In fact, nuclear fusion reactions are responsible for the energy output of most stars, including our own Sun.

• A chain reaction is a sequence of reactions where a reactive product or by-product causes additional reactions to take place. In each of the above reactions, 1 neutron splits the atom. When the atom is split, 1 additional neutron is released. This is how a chain reaction works. If more 235U is present, those 2 neutrons can cause 2 more atoms to split. Each of those atoms releases 1 more neutron bringing the total neutrons to 4. Those 4 neutrons can strike 4 more 235U atoms, releasing even more neutrons. The chain reaction will continue until all the 235U fuel is spent. This is roughly what happens in an atomic bomb. It is called a runaway nuclear reaction.

CHAIN REACTION

Chain reaction of thorium

Chain reaction of uranium

Nuclear Power in India(The above picture shows the nuclear reactors

currently operational in India)

Nuclear Power in India

Nuclear power is the fourth largest source of electricity in India after thermal, hydroelectric and renewable sources of electricity.

As of 2010, India has 20 nuclear reactors in operation in six nuclear power plants, generating 4,780 MW.

Seven other reactors are under construction and are expected to generate an additional 5,300  MW.

Advantages of Nuclear Energy• The Earth has limited

supplies of coal and oil. Nuclear power plants could still produce electricity after coal and oil become scarce.

• Nuclear power plants need less fuel than ones which burn fossil fuels. One ton of uranium produces more energy than is produced by several million tons of coal or several million barrels of oil.

• Coal and oil burning plants pollute the air. Well-operated nuclear power plants do not release contaminants into the environment.

Disadvantages of Nuclear Energy

• Nuclear explosions result in large amounts of radiation. The nuclear radiation harms the cells of the body which can make people sick or even kill them. Illness can strike people years after their exposure to nuclear radiation.

• Reactors produce nuclear waste products which emit dangerous radiation. Since they can kill people who touch them, they cannot be thrown away like ordinary garbage. 

• In nuclear plants, there is a risk of a meltdown. During a meltdown, the fission reaction goes out of control, leading to a nuclear explosion and the emission of great amounts of radiation.

Major nuclear meltdowns

Three Mile accident- The Three Mile Island accident was a partial nuclear meltdown which occurred at the Three Mile Island power plant in Pennsylvania. It resulted in a loss of coolant and partial core meltdown due to operator errors.

Chernobyl Disaster- One of the worst nuclear accidents to date was the Chernobyl disaster which occurred in 1986 in Ukraine. This accident killed 56 people directly, as well as damaging approximately $7 billion of property. Overheating, steam explosion, fire, and meltdown, necessitating the evacuation of 300,000 people from Kiev and dispersing radioactive material across Europe .

Fukushima Daiichi-A tsunami flooded and damaged the 5 active reactor at the Fukushima Daiichi nuclear plant. Loss of backup electrical power led to overheating, meltdowns, and evacuations. 3 reactors underwent a complete meltdown..

Recent developments in Nuclear EnergyAlthough nuclear power is currently a significant source of

global electricity supply, there is no consensus concerning its future role. While nuclear power stagnates in much of Europe and in North America, it continues as a strong option in some Asian countries

Although there is debate about its use, nuclear energy is eco friendly as decommissioning it does not involve environmental pollution and greenhouse gas emissions.

A newly discovered form of uranium, uranium nitride, could lead to a nuclear power plant small enough to fit in your car and eventually even power it

India has also sought to build new nuclear plants, so as to meet its massive energy needs