↑ Вгору

Реферат на тему

What is energy


Переглянути реферат


Скачати реферат


Друкувати реферат

What is energy.

Everything in the universe is either energy or matter. For us humans,
energy is the means for doing work. Picking up a book, watching TV or
launching a Space Shuttle all needs energy. Without it there would be no
life, for all life uses energy.

Energy, so far as we are concerned, comes from only two sources: the
Sun and the decay of radioactive elements inside the Earth. The Sun
radiates its warmth out to all the planets, but ours happens to be about
the right distance away to be able to support Life. In fact, Life seems
to control the temperature of the planet like a thermostat.

But what about oil, gas or coal, which also come from inside the
Earth? They were formed because of the energy from ancient sunshine from
millions of years ago driving life on Earth. These have formed 'fossil
fuels' or 'non-renewable' energy sources.

Energy is the power that we use to do things, whether it is thinking
about building a ship or actually building it. Building it needs large
amounts of energy to power blast furnaces to make the steel, mills to
roll it and electricity to weld it to form the ship's structure. That
ship, when built, has engines, which push it through the water. Most
energy is not available to us in a usable form. We have to convert it
into another form to make it work for us.

Here are two examples:

A fast-flowing river is full of energy we can't use. If you dam it and
install turbines, you get electricity.

Coal is just black rock with one odd property ... it burns. If you burn
it, you can warm your home, cook food or raise steam in a boiler - to
make electricity.

Life needs energy. Life's energy is self-perpetuating only so long as
there is sunshine. Plants can convert it and store it for their next
generation (as in potato tubers, groundnuts, rice or peas). Animals eat
the plants or each other, die and decompose, freeing nutrients for
plants again. It is a sustainable cycle. For hundreds of thousands of
years, humans have merely been a part of this cycle. Then we got clever
and discovered that we could use energy other than from our own muscles
to do work for us.

First we discovered that wind could drive our ships and water could
power our mills. Later, we found that coal could make heat and steam for
machinery. Then came oil and gas and nuclear power, all needed in
increasingly large amounts to fuel our endless appetite for being
comfortable and doing things with as little effort as possible. So we
heat our homes, schools and workplaces in the winter. In the richer
countries, most people have a car (or several) so that they can travel
about. Transport guzzles huge amounts of energy - all so that we can
have goods and services when we want them.

Kinds of energy resources.

Almost all of the energy we use comes from non-renewable sources.

All non-renewable energy sources create pollution, in part due to their
extraction from the crust of our planet but mainly from their burning.
Only two types exist: the fossil fuels (coal, oil and natural gas) and

two types exist: the fossil fuels (coal, oil and natural gas) and
nuclear fuels (uranium, plutonium and, for the future, unusual types -
isotopes - of hydrogen such as deuterium and tritium).

HYPERLINK "http://www.oneworld.org/energy/pictures.htm" \l "plume"
Fossil fuels are useful to us only because they liberate heat energy
when we burn the carbon they contain. "Burning" - combustion - is really
oxidation; making carbon and oxygen combine to liberate heat.
Unfortunately for us, the principal byproduct is carbon dioxide, CO2.
Most scientists believe that this is an important contributor to global
warming. The heat from coal, gas and oil we can use either directly or
indirectly to raise steam in boilers and generate electricity using
steam turbines to drive generators. By contrast, properly managed
nuclear fuels liberate no pollution to the atmosphere at all. Accidents
are rare in the nuclear power industry but when they occur, their
potential for long-lasting damage is horrific. The disaster at Chernobyl
on April 26, 1986 was by far the world's worst nuclear accident.

Coal is carbon; so is graphite (lead pencils) and diamond (a girl's
best friend as well as the hardest substance known). Every living
organism is made up of molecules based on carbon. Without carbon, there
would be no life. Coal is the most plentiful fossil fuel and,
unfortunately, the most polluting. Like oil and gas, coal started as
living plants - mostly trees - in low lying swampy areas not much above
sea level, tens or hundreds of millions of years ago. As the trees died,
they did not decompose (as they normally would, returning the carbon
locked in their tissues to the atmosphere). Because of the water
logging, normal decay processes couldn't function. So thick layers of
peat built up over thousands of years. These then became covered in
sands or muds as the land subsided. As more material accumulated above
the peat, the water was squeezed out leaving just carbon-rich plant
remains. After millions of years, this slowly changed - metamorphosis -
(like the oil and gas from the plankton) into coal.

Nuclear power taps the ultimate source of energy, which powers the
universe, and its myriads of stars like our Sun. It exploits the famous
E=mc2 [e1] equation, which shows that matter, can change into energy.
Nuclear engineers deliberately arrange to "split" certain atoms - this
is called nuclear fission. When this happens, some matter gets destroyed
- liberating huge amounts of energy. This energy mostly ends up as heat
from which you can make steam to drive turbines and generators, and make
electricity in power stations. In the Sun, atoms of hydrogen fuse to
create helium and liberate the seemingly endless stream of energy we
call sunlight. Without this solar fusion reactor 150 million kilometers
away, our home planet would be a frigid lifeless world. Scientists hope
to reproduce this fusion reaction in a controlled way to yield almost
unlimited energy supplies with far fewer radioactive waste problems. So

h far fewer radioactive waste problems. So
far, they've only managed the uncontrolled reactions ... hydrogen bombs.
HYPERLINK "http://www.oneworld.org/energy/pictures.htm" \l "nucnuc"
The discovery of nuclear reactions is a wonderful example of the
neutrality or indifference of science. Like so many other discoveries,
humans for good or for ill could exploit nuclear reactions. The
pressures of war caused the ill to be developed first but out of that
development came an industry, which now provides 22% of electricity
supply in the OECD countries. In France, it provides 73%; in the UK 23%
and 17% in the USA. And whilst it's true that the two nuclear bombs used
in anger on Japan killed and maimed hundreds of thousands, they have
some way to go to catch up with the hundreds of millions of people
who've lost their lives because of ordinary bombs, high-explosive
shells, bullets and mines. Many claim that the very existence of nuclear
weapons has prevented major conflict since World War 2. But what really
scares people - and rightly so - is that modern nuclear weapons could
destroy the entire planet ... if they're ever used in anger again. So
now, there are forces -like the World Court Project - afoot to make
their possession and use illegal throughout the world. On the other
hand, many countries view with disgust the idea that the nuclear "haves"
should keep their weapons whilst making sure that the "have nots" don't
get any; a kind of nuclear imperialism. This is a good reason for making
all such weapons illegal. Otherwise, proliferation is a worry,
particularly since the break-up of the Soviet Union, which has
inadvertently made weapons-grade materials available on the
international black market. Sooner or later, extremists will accumulate
enough of this to build a crude device, which could easily be carried by
a vehicle, driven into a major city and detonated. The prospects are
frightening. As in any industry, accidents happen. Serious accidents can
mean the spreading of dangerous radioactivity into the environment.
Several serious accidents have occurred, as everyone knows. Several
other less well-known accidents associated with the race to build
nuclear weapons occurred in the former Soviet Union, causing the
contamination of hundreds of square kilometers of land. Renewable
sources - Renewable energy sources have long been energy's Cinderella.
Today, wind power is finally coming into its own. Denmark, already
employing 12,000 people in its wind industry, intends wind power to
produce half its total electricity needs by 2030. Several major wave
power projects are now underway and solar energy is booming in Germany,
the western USA and, in a smaller way, in remoter parts of the South.
Equally important in cold climates is the design of buildings to capture
'passive' energy and retain it through insulation. Other minor
renewables include geothermal power in volcanically active countries
like Iceland, while tidal barrages remain a possibility in the UK and

he UK and
eastern Canada.

People use some kinds of renewable sources.

At first, it is wind energy. We have been harnessing the wind's
energy for hundreds of years. From old Holland to farms in the United
States, windmills have been used for pumping water or grinding grain.
Today, the windmill's modern equivalent – a wind turbine – can use the
wind's energy to generate electricity.  Wind turbines, like windmills,
are mounted on a tower to capture the most energy. At 100 feet (30
meters) or more aboveground, they can take advantage of the faster and
less turbulent wind. Turbines catch the wind's energy with their
propeller-like blades. Usually, two or three blades are mounted on a
shaft to form a rotor. A blade acts much like an airplane wing. When the
wind blows, a pocket of low-pressure air forms on the downwind side of
the blade. The low-pressure air pocket then pulls the blade toward it,
causing the rotor to turn. This is called lift. The force of the lift is
actually much stronger than the wind's force against the front side of
the blade, which is called drag. The combination of lift and drag causes
the rotor to spin like a propeller, and the turning shaft spins a
generator to make electricity. Wind turbines can be used as stand-alone
applications, or they can be connected to a utility power grid or even
combined with a photovoltaic (solar cell) system. Stand-alone wind
turbines are typically used for water pumping or communications.
However, homeowners or farmers in windy areas can also use wind turbines
as a way to cut their electric bills. For utility-scale sources of wind
energy, a large number of wind turbines are usually built close together
to form a wind plant. Several electricity providers today use wind
plants to supply power to their customers.

At second, it is bio energy. We have used bio energy – the energy from
biomass (organic matter) – for thousands of years, ever since people
started burning wood to cook food or to keep warm. And today, wood is
still our largest biomass resource for bio energy. But many other
sources of biomass can now be used for bio energy, including plants,
residues from agriculture or forestry, and the organic component of
municipal and industrial wastes. Even the fumes from landfills can be
used as an energy source.

The use of bio energy has the potential to greatly reduce our greenhouse
gas emissions. Bio energy generates about the same amount of carbon
dioxide as fossil fuels, but every time a new plant grows, carbon
dioxide is actually removed from the atmosphere. The net emission of
carbon dioxide will be zero as long as plants continue to be replenished
for bio energy purposes. These energy crops, such as fast-growing trees
and grasses, are called bio energy feedstocks. The use of bio energy
feedstocks can also help increase profits for the agricultural industry.

I think, that it is very important to use sun energy. The Sun is the
center of our solar system and the source of life on the planet earth.

lanet earth.
Moreover, as petroleum continues to pollute and destroy the earth, what
better way than to look to the Sun for a solution?

The earth and either being used or simply bouncing off are always
capturing the heat from the Sun. Solar technology utilizes this heat
energy and converts it to electrical energy, which is then fed into the
power grid for users. That, albeit, is not all. One of the benefits of
solar energy is its ability to be used widely and in specialized
situations. For instance, "Small systems can be installed on the roofs
of homes to heat water for domestic use. Moderate-size systems can
supply hot water, steam, and hot air to schools, hospitals, businesses,
and industries. Large solar thermal electric installations can generate
electricity in quantities comparable to those generated in
intermediate-size utility generating plants (that is, 100 to 200
megawatts [MW] of electricity)."

One myth about solar power is that it requires large areas of land in
order to be deemed useful. One example of this falsity is "Solar
collectors covering less than half of Nevada could supply all of the
United States' energy needs." While that seems like a lot of land, that
area divided my 50 states and spread out could almost go unnoticed. One
of solar powers biggest advantages is cost. For 1% of the construction
cost on a building, solar panels installed could save up to 50% on
heating bills. In addition, at a more consumer level, a resident of a
home could save almost $500 within just the first year of installation.
As an added bonus, the savings are likely to increase over the years due
largely to increase in electrical bills. Thus, a solar heating system is
capable of paying for itself in less than 10 years. The answer to the
energy crisis the world is seeing could be to simply return to that with
we depends on already, the Sun.

Flowing water creates energy that can be captured and turned into
electricity. This is called hydropower. The most common type of
hydropower plant uses a dam on a river to store water in a reservoir.
Water released from the reservoir flows through a turbine, spinning it,
which in turn activates a generator to produce electricity. But
hydropower doesn't necessarily require a large dam. Some hydropower
plants just use a small canal to channel the river water through a
turbine. Another type of hydropower plant – called a pumped storage
plant – can even store power. The power is sent from a power grid into
the electric generators. The generators then spin the turbines backward,
which causes the turbines to pump water from a river or lower reservoir
to an upper reservoir, where the power is stored. To use the power, the
water is released from the upper reservoir back down into the river or
lower reservoir. This spins the turbines forward, activating the
generators to produce electricity.

The ocean can produce two types of energy: thermal energy from the
sun's heat, and mechanical energy from the tides and waves. Oceans cover

aves. Oceans cover
more than 70% of Earth's surface, making them the world's largest solar
collectors. The sun's heat warms the surface water a lot more than the
deep ocean water, and this temperature difference creates thermal
energy. Just a small portion of the heat trapped in the ocean could
power the world. Ocean thermal energy is used for many applications,
including electricity generation. Ocean mechanical energy is quite
different from ocean thermal energy. Even though the sun affects all
ocean activity, tides are driven primarily by the gravitational pull of
the moon, and waves are driven primarily by the winds. As a result,
tides and waves are intermittent sources of energy, while ocean thermal
energy is fairly constant. Also, unlike thermal energy, the electricity
conversion of both tidal and wave energy usually involves mechanical
devices. A barrage (dam) is typically used to convert tidal energy into
electricity by forcing the water through turbines, activating a
generator. For wave energy conversion, there are three basic systems:
channel systems that funnel the waves into reservoirs; float systems
that drive hydraulic pumps; and oscillating water column systems that
use the waves to compress air within a container. The mechanical power
created from these systems either directly activates a generator or
transfers to a working fluid, water, or air, which then drives a


Thus, humanity uses many kinds of energy: renewable and non-renewable.
To make sure we have plenty of energy in the future, it's up to all of
us to use energy wisely. We must all conserve energy and use it
efficiently. It also up to those of you who will want to create the new
energy technologies of the future. One of you might be another Albert
Einstein and find a new source of energy. It's up to all of us. The
future is ours but we need energy to get there.

The world has changed dramatically over the last 200 years, thanks
largely to fossil fuels – coal, oil and natural gas. These have provided
us with cheap and convenient energy, which we use to heat and cool our
homes and to run our cars, appliances and industries. But there has been
a cost. No city in the world is immune from the polluting effects of
fossil fuels, and they contribute vast quantities of greenhouse gases to
the atmosphere, something that many scientists believe causes global
warming. So, in the last few decades, scientists have been looking for
ways to produce energy without adverse side effects. Promising renewable
energy sources such as wind, direct solar and biomass are dealt with in
other Nova topics (see links at the end of this page). Now we'll have a
look at hot dry rocks, waves and hydrogen. It may be some years before
these energy sources make a big impact but they illustrate the diversity
of options that are available.

Energy resources year 10
DATE \@ "dd.MM.yyyy"


Alexey Ardalin

Page PAGE 1

© 2013 Alive-inter.net Про сайт Alive-inter.net Зворотній зв`язок Відмова від відповідальності