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 nuclear fuels (uranium, plutonium and, for the
future, unusual types - isotopes - of hydrogen such as deuterium
and tritium). http: //www. oneworld. org/energy/pictures. htm -
plumeFossil 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. http: //www. oneworld.
org/energy/pictures. htm - planktonPhytoplankton are tiny floating
plants called algae. The commonest are golden or brown colored
diatoms and din flagellates. Zooplankton are tiny animals, which
eat the phytoplankton but are themselves the main food for fish and
some whales. Oil (petroleum) and natural gas formed by complex
decay processes from microscopic life forms called phytoplankton
(phyto=plant) which floated in the world's oceans millions of years
ago. Just like today's phytoplankton, they harnessed the Sun to
photosynthesis and store energy. When these myriads of tiny
floating plants died, they sank to the sea floor and became mixed
with muds from distant rivers, and were gradually buried. Over
immense periods of time, the soft sediments became ever more deeply
buried and slowly hardened into rocks. Heat from the Earth's
interior and the weight of the overlying rocks gradually changed
the energy-containing substances in the accumulated plants into
hydrocarbon liquids and gases. Hydrocarbons are simple molecules
made up of carbon and hydrogen atoms joined together in chains or
in rings. These molecules, being light and mobile, migrated upwards
through the rocks but eventually became trapped beneath impermeable
rock structures in the Earth's crust. The oil and gas companies
around the world know how to find these trapped reservoirs and
release their contents by drilling holes into them. As everyone
knows, crude oil and gas from these deposits form the basis for the
world's largest energy industry: oil and gas. Much oil and gas
production now comes from underneath the seabed. As the technology
for extraction continues to advance, production becomes possible
from deeper and deeper waters. This means that new oil and gas
fields will continue to be found for some years yet so the early
forecasts of oil running dry have proved to be wrong. But we know
that the supplies are limited. We also know that every drop of oil
we burn adds to the monumental environment problems we already have
by pumping gases like carbon dioxide (CO2) into the atmosphere.
Many scientists worry that this continual release of CO2 is an
important cause of global warming. Ошибка! Неизвестный аргумент
ключа. 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 far,
they've only managed the uncontrolled reactions .... hydrogen
bombs. http: //www. oneworld. org/energy/pictures. htm - nucnucThe
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 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.
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 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 turbine/generator.
Conclusion.
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.
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