Assignments Portal: BIOL 101 MAN AND ENVIRONMENT ASSIGNMENT

Need of Energy

Types of Energy

Advantages and Disadvantages

Energy is defined as power of doing work. Human beings and other species that are living or non-living require energy in order to perform various activities. Any form of energy can be transformed into another form, but the total energy always remains the same.

Why do we need energy?

Energy is very important to survive. As energy is ability to do work so we need energy to move and do the things. We need energy for all our muscles to work. All the cells in our body require energy to carry out the required chemical reactions to complete their specific functions. Machines are created, a vehicle needs energy to move, so the gasoline/diesel is being processed in the vehicle engine, and then converted to the energy needed. So we use energy to run cars, planes, trains, buses and motorcycles. For example, we use different energy sources to generate the electricity we need for our homes, schools, businesses and factories. Electricity powers our TVs, computers, air conditioners and many other electronic devices.

Types of Energy

There are different types of energy in the universe. Potential energy and, mechanical energy, chemical energy, kinetic energy, etc are some of the common forms of energy. Even an object that is lying on the ground stores an amount of potential energy in it. When you lift the object or move the object, its potential energy is changed into kinetic energy. We make the use of one form of energy in order to produce the other form of energy. Waterfall in from a height possesses great amount of kinetic energy and when it falls on the water turbine, it rotates it and produces electricity. Human being has invented new ways of transferring one form of energy into another form of energy.

The energy sources have been split into three categories:

· fossil fuels

· renewable sources

· nuclear sources

The fossil fuels covered here are coal, petroleum, and natural gas. The renewable energy sources are solar, wind, hydroelectric, biomass, and geothermal power. The nuclear-powered sources are fission and fusion.

Fossil Fuels

Coal, oil and gas are called "fossil fuels" because they have been formed from the organic remains of prehistoric plants and animals.

How it works:

· Coal is crushed to a fine dust and burnt.

· Oil and gas can be burnt directly.

Coal provides around 28% of our energy, and oil provides 40%. Burning coal produces sulphur dioxide, an acidic gas that contributes to the formation of acid rain. This can be largely avoided using "flue gas desulphurisation" to clean up the gases before they are released into the atmosphere. This method uses limestone, and produces gypsum for the building industry as a by-product. However, it uses a lot of limestone.

Crude oil (called "petroleum") is easier to get out of the ground than coal, as it can flow along pipes. This also makes it cheaper to transport.

Natural gas provides around 20% of the world's consumption of energy, and as well as being burnt in power stations, is used by many people to heat their homes.
It is easy to transport along pipes, and gas power stations produce comparatively little pollution.

Advantages

Very large amounts of electricity can be generated in one place using coal, fairly cheaply.
Transporting oil and gas to the power stations is easy.
Gas-fired power stations are very efficient.
A fossil-fuelled power station can be built almost anywhere, so long as you can get large quantities of fuel to it.

Disadvantages

Basically, the main drawback of fossil fuels is pollution.
Burning any fossil fuel produces carbon dioxide, which contributes to the "greenhouse effect", warming the Earth.
Burning coal produces more carbon dioxide than burning oil or gas.
It also produces sulphur dioxide, a gas that contributes to acid rain. We can reduce this before releasing the waste gases into the atmosphere.

· Mining coal can be difficult and dangerous. Strip mining destroys large areas of the landscape.

· Fossil fuels are not a renewable energy resource. Once we've burned them all, there isn't any more, and our consumption of fossil fuels has nearly doubled every 20 years since 1900. This is a particular problem for oil, because we also use it to make plastics and many other products.

RENEWABLE SOURCES

Solar Energy The energy of the sun can be used in many ways. When plants grow, they store the energy of the sun. Then, when we burn those plants, the energy is released in the form of heat. This is an example of indirect use of solar energy.

The form we are interested in is directly converting the sun's rays into a usable energy source: electricity. This is accomplished through the use of "solar collectors," or, as they are more commonly known as, "solar panels."

There are two ways in which solar power can be converted to energy. The first, known as "solar thermal applications," involve using the energy of the sun to directly heat air or a liquid. The second, known as "photoelectric applications," involve the use of photovoltaic cells to convert solar energy directly to electricity.

Solar power has an exciting future ahead of it. Because solar power utilizes the sun's light, a ubiquitous resource (a resource that is everywhere), solar panels can be attached to moving objects, such as automobiles, and can even be used to power those objects. Solar powered cars are being experimented with more and more frequently now.

Advantages

Solar energy is free - it needs no fuel and produces no waste or pollution.
In sunny countries, solar power can be used where there is no easy way to get electricity to a remote place.
Handy for low-power uses such as solar powered garden lights and battery chargers, or for helping your home energy bills.

Disadvantages

Doesn't work at night.
Very expensive to build solar power stations. Solar cells cost a great deal compared to the amount of electricity they'll produce in their lifetime.
Only areas of the world with lots of sunlight are suitable for solar power generation.

Wind power is the conversion of wind energy into a useful form, such as electricity, using wind turbines. Wind energy has historically been used directly to propel sailing ships or converted into mechanical energy for pumping water or grinding grain, but the principal application of wind power today is the generation of electricity. We can use the energy in the wind by building a tall tower, with a large propeller on the top. The wind blows the propeller round, which turns a generator to produce electricity.

Advantages

· Wind is free, wind farms need no fuel.

· Produces no waste or greenhouse gases.

· The land beneath can usually still be used for farming.

Disadvantages

· Very diffuse source means low energy production--large numbers of wind generators (and thus large land areas) are required to produce useful amounts of heat or electricity.

· The wind is not always predictable - some days have no wind.

· Suitable areas for wind farms are often near the coast, where land is expensive.

· Some people feel that covering the landscape with these towers is unsightly.

Hydroelectric systems make use of the energy in running water to create electricity. A dam is built to trap water, usually in a valley where there is an existing lake. Water is allowed to flow through tunnels in the dam, to turn turbines and thus drive generators. Hydro-electric power stations can produce a great deal of power very cheaply.

Advantages

· No waste or pollution produced.

· Much more reliable than wind, solar or wave power.

Disadvantages

· Smaller models depend on availability of fast flowing streams or rivers.

· Finding a suitable site can be difficult - the impact on residents and the environment may be unacceptable.

· Building a large dam will flood a very large area upstream, causing problems for animals that used to live there.

Biomass is the conversion of stored energy in plants into energy that we can use. Sugar cane is grown in some areas, and can be fermented to make alcohol, which can be burned to generate power. Alternatively, the cane can be crushed and the pulp can be burned, to make steam to drive turbines. "Bioconversion" uses plant and animal wastes to produce "biofuels" such as methanol, natural gas, and oil.

Advantages

It makes sense to use waste materials where we can.
The fuel tends to be cheap.
Less demand on the fossil fuels.

Disadvantages

Collecting or growing the fuel in sufficient quantities can be difficult.
We burn the biofuel, so it makes greenhouse gases just like fossil fuels do.
Some waste materials are not available all year round.

Geothermal Power Hot rocks underground heat water to produce steam. The earth's crust is heated by the decay of radioactive elements. The heat is carried by magma or water beneath the earth's surface. We drill holes down to the hot region; steam comes up, is purified and used to drive turbines, which drive electric generators.

Geothermal power can be used to directly heat buildings. Further, the pressurized steam from superheated water beneath the earth's surface can be used to power turbines and thus generate electricity.

Advantages

· Geothermal energy does not produce any pollution, and does not contribute to the greenhouse effect.

· The power stations do not take up much room, so there is not much impact on the environment.

· No fuel is needed.

· Geothermal energy is renewable. The energy keeps on coming, as long as we don't pump too much cold water down and cool the rocks too much.

Disadvantages

· The big problem is that there are not many places where you can build a geothermal power station. You need hot rocks of a suitable type, at a depth where we can drill down to them. The type of rock above is also important, it must be of a type that we can easily drill through.

· Sometimes a geothermal site may run out of steam.

· Hazardous gases and minerals may come up from underground, and can be difficult to safely dispose of.

NUCLEAR SOURCES

Nuclear power is any nuclear technology designed to extract usable energy from atomic nuclei via controlled nuclear reactions. The only method in use today is through nuclear fission, though other methods might one day include nuclear fusion. Nuclear power is generated using Uranium and some military ships and submarines have nuclear power plants for engines. Nuclear power produces around 11% of the world's energy needs, and produces huge amounts of energy from small amounts of fuel, without the pollution that you'd get from burning fossil fuels.

Nuclear Fission produces energy for nuclear power and to drive the explosion of nuclear weapons. Fission of heavy elements is an exothermic reaction which can release large amounts of energy both as electromagnetic radiation and as kinetic energy. The energy produced by fission is used primarily to heat a liquid (usually water) to boiling. The steam generated by the boiling liquid is used to power a turbine that generates electricity.

Advantages

Nuclear power costs about the same as coal, so it's not expensive to make.
Does not produce smoke or carbon dioxide, so it does not contribute to the greenhouse effect.
Produces huge amounts of energy from small amounts of fuel.
Produces small amounts of waste.
Nuclear power is reliable.

Disadvantages

· Although not much waste is produced, it is very, very dangerous. It must be sealed up and buried for many thousands of years to allow the radioactivity to die away. For all that time it must be kept safe from earthquakes, flooding, terrorists and everything else. This is difficult.

· Nuclear power is reliable, but a lot of money has to be spent on safety - if it does go wrong, a nuclear accident can be a major disaster.

Nuclear Fusion The fusion is the process that powers the stars. The energy that comes from the process relies on the joining, or "fusing," of two atoms to form a new molecule. When this larger, relatively unstable molecule splits apart, it releases energy. Tritium and deuterium atoms don't randomly collide and give off energy. They must be heated up to extremely high temperatures (around 100 million degrees) in order for fusion to take place.

Advantages

The fuel for fusion reactions is readily available. Deuterium and Tritium are virtually inexhaustible.
Unlike the burning of coal or other fossil fuels, fusion does not emit harmful toxins into the atmosphere. The combustion of most fossil fuels involves some form of the reaction.

Disadvantages

Tritium and deuterium atoms must be heated up to extremely high temperatures (around 100 million degrees) in order for fusion to take place.
Many countries are phasing out fusion research because of the failure to reach a breakthrough.

REFERENCES

http://home.clara.net/darvill/altenerg/index.htm

http://library.thinkquest.org/20331/types/fossil/theory.html

http://simple.wikipedia.org/wiki/Energy

http://en.wikipedia.org/wiki/Nuclear_power

http://uk.answers.yahoo.com/question/index?qid=20090417201514AA8iUnH

http://www.depweb.state.pa.us/justforkids/cwp/view.asp?a=3&q=472531