NUCLEAR ENERGY (URANIUM) ENERGY FROM
ATOMS
Nuclear power accounts for about 20 percent of the total electricity
generated in the United States, an amount comparable to all the electricity
used in California,Texas and New York, our three most populous (having
the most people) states. In 2000, there were 66 nuclear power plants
(composed of 104 licensed nuclear reactors) throughout the United
States, located mostly on the East Coast and in the Midwest.
A nuclear power plant operates basically the same way as a
fossil fuel plant, with one difference: the source of heat. The process
that produces the heat in a nuclear plant is the fissioning or splitting
of uranium atoms. That heat boils water to make the steam that turns
the turbine-generator, just as in a fossil fuel plant. The part of
the plant where the heat is produced is called the reactor core.
NUCLEAR FUEL
Atoms are made up of three major particles: protons, neutrons and
electrons. The most common fissionable atom is an isotope (the specific
member of the atom's family) of uranium known as uranium-235 (U-235
or U235), which is the fuel used in most types of nuclear reactors
today. Although uranium is quite common, about 100 times more common
than silver, U-235 is relatively rare. Most U.S. uranium is mined,
in the Western United States. Once uranium is mined the U-235 must
be extracted and processed before it can be used as a fuel. In its
final usable state, the nuclear fuel will be in the form of a pellet
roughly one-inch-long, which can generate approximately the same amount
of electricity as one ton of coal.
TYPE OF REACTORS
Just as there are different approaches to designing and building
airplanes and automobiles, engineers have developed different types
of nuclear power plants. Two types are used in the United States:
boiling-water reactors (BWR's), and pressurized-water reactors (PWR's).
In the BWR, the water heated by the reactor core turns directly into
steam in the reactor vessel and is then used to power the turbine-generator.
In a PWR, the water passing through the reactor core is kept under
pressure so that it does not turn to steam at all -- it remains liquid.
Steam to drive the turbine is generated in a separate piece of equipment
called a steam generator. A steam generator is a giant cylinder with
thousands of tubes in it through which the hot radioactive water can
flow. Outside the tubes in the steam generator, non radioactive water
(or clean water) boils and eventually turns to steam. The clean water
may come from one of several sources: oceans, lakes or rivers. The
radioactive water flows back to the reactor core, where it is reheated,
only to flow back to the steam generator. Roughly seventy percent
of the reactors operating in the U.S. are PWR.
Nuclear reactors are basically machines that contain and control
chain reactions, while releasing heat at a controlled rate. In electric
power plants, the reactors supply the heat to turn water into steam,
which drives the turbine-generators. The electricity is shipped or
distributed through transmission lines to homes, schools, hospitals,
factories, office buildings, rail systems and other customers.
ENVIRONMENT
Like all industrial processes, nuclear power generation has by-product
wastes: radioactive waste and hot water. Because nuclear generated
electricity does not emit carbon dioxide into the atmosphere, nuclear
power plants in the U.S. prevent about as much greenhouse has emissions
as taking 5 billion cars off our streets and highways.
Radioactive wastes are the principal environmental concern for nuclear
power. Most nuclear waste is low-level nuclear waste. It is ordinary
trash, tools, protective clothing, wiping cloths and disposable items
that have been contaminated with small amounts of radioactive dust
or particles. These materials are subject to special regulation that
govern their storage so they will not come in contact with the outside
environment.
On the other hand the irradiated fuel assemblies are highly radioactive
and must be stored in specially designed pools resembling large swimming
pools (water cools the fuel and acts as a radiation shield) or in
specially designed dry storage containers. The older and less radioactive
fuel is kept in the dry storage facility. It is sealed in special
concrete reinforced containers. The United States Department of Energy's
long range plan is for this spent fuel to be stored deep in the earth
in a geologic repository. The proposed site is Yucca Mountain, Nevada.
Currently, all spent (used) fuel is stored at the power plant at which
it was used.
Petroleum (Oil) -- A Fossil Fuel
Oil was formed from the remains of animals and plants that lived millions
of years ago in a marine (water) environment before the dinosaurs.
Over the years, the remains were covered by layers of mud. Heat and
pressure from these layers helped the remains turn into what we today
call crude oil . The word "petroleum" means "rock oil"
or "oil from the earth."
WHERE DOES OIL COME FROM?
Crude oil is a smelly, yellow-to-black liquid and is usually found
in underground areas called reservoirs. Scientists and engineers explore
a chosen area by studying rock samples from the earth. Measurements
are taken, and, if the site seems promising, drilling begins. Above
the hole, a structure called a 'derrick' is built to house the tools
and pipes going into the well. When finished, the drilled well will
bring a steady flow of oil to the surface.
The world's top five crude oil-producing countries are:
Saudi
Arabia
Russia
United
States
Iran
China
The amount of crude oil produced (domestically) in the United States
has been getting smaller each year. However, the use of products made
from crude oil has been growing, making it necessary to bring more
oil from other countries. Over 50 percent of the crude oil and petroleum
products used in the United States comes from other countries.
HOW IS IT USED?
After crude oil is removed from the ground, it is sent to a refinery
by pipeline, ship or barge. At a refinery, different parts of the
crude oil are separated into useable petroleum products. Crude oil
is measured in barrels. A 42-U.S. gallon barrel of crude oil provides
slightly more than 44 gallons of petroleum products. This gain from
processing the crude oil is similar to what happens to popcorn, it
gets bigger after it is popped.
One barrel of crude oil, when refined, produces 19.4 gallons of finished
motor gasoline, as well as other petroleum products. Most of the petroleum
products are used to produce energy. For instance, many people across
the United States use propane to heat their homes and fuel their cars.
Other products made from petroleum include: ink, crayons, bubble gum,
dishwashing liquids, deodorant, eyeglasses, records, tires, ammonia,
and heart valves.
OIL AND THE ENVIRONMENT
When petroleum products such as gasoline (used in automobiles), diesel
fuel (used in trucks), and heating oil (used to heat our homes) are
burned as fuel, they give off carbon dioxide. Drilling for oil also
has an impact on the environment--companies must use advanced technology
and comply with government rules and regulations for safe drilling
and petroleum production.
Natural Gas -- A Fossil Fuel
Millions of years ago, the remains of plants and animals decayed and
built up in thick layers. This decayed matter from plants and animals
is called organic material -- it was once alive. Over time, the mud
and soil changed to rock, covered the organic material and trapped
it beneath the rock. Pressure and heat changed some of this organic
material into coal, some into oil (petroleum), and some into natural
gas -- tiny bubbles of odorless gas. The main ingredient in natural
gas is methane, a gas (or compound) composed of one carbon atom and
four hydrogen atoms.
HOW WE DISCOVERED NATURAL GAS
Gas escapes from small gaps in the rocks into the air; then, if there
is enough activation energy from lightning or a fire, it burns. When
people first saw the flames, they experimented with them and learned
they could use them for heat and light.
HOW WE GET NATURAL GAS
The search for natural gas begins with geologists (people who study
the structure of the earth) locating the types of rock that are usually
found near gas and oil deposits.
Today their tools include seismic surveys that are used to find the
right places to drill wells. Seismic surveys use echoes from a vibration
source at the earth’s surface (usually a vibrating pad under
a truck built for this purpose) to collect information about the rocks
beneath. Sometimes it is necessary to use small amounts of dynamite
to provide the vibration that is needed.
Scientists and engineers explore a chosen area by studying rock samples
from the earth and taking measurements. If the site seems promising,
drilling begins. Once the gas is found, it flows up through the well
to the surface of the ground and into large pipelines. Some of the
gases that are produced along with methane, such as butane and propane
(also known as 'by-products'), are separated and cleaned at a gas
processing plant. The by-products, once removed, are used in a number
of ways. For example, propane can be used for cooking on gas grills.
Because natural gas is colorless, odorless and tasteless, mercaptan
(a chemical that has a sulfur like odor) is added before distribution,
to give it a distinct unpleasant odor (smells like rotten eggs). This
serves as a safety device by allowing it to be detected in the atmosphere,
in cases where leaks occur.
We can also use machines called "digesters" that turn today's
organic material (plants, animal wastes, etc.) into natural gas. This
replaces waiting for thousands of years for the gas to form naturally.
WHAT NATURAL GAS IS USED FOR
Approximately 23 % of the energy consumption of the U.S. comes from
natural gas. Over one-half of the homes in the U.S. use natural gas
as their main heating fuel.
Natural gas is also an essential raw material for many common products,
such as: paints , fertilizer, plastics, antifreeze, dyes, photographic
film, medicines, and explosives. We also get propane, a fuel we use
in many of our backyard barbecue grills, when we process natural gas.
Industry depends on it. Natural gas has thousands of uses. It's used
to produce steel, glass, paper, clothing, brick, electricity and much
more!
Homes use it too. More than 61.9 million homes use natural gas to
fuel stoves, furnaces, water heaters, clothes dryers and other household
appliances. It is also used to roast coffee, smoke meats, bake bread
and much more.
NATURAL GAS AND THE ENVIRONMENT
Natural gas is a cleaner fossil fuel. By this we mean it produces
relatively few pollutants, so the air inside and outside stays clean.
Natural gas also has fewer emissions than coal or oil and has virtually
no ash particles left after burning.
COAL -- A Fossil Fuel
IT'S USEFUL
Coal is used to generate more than half of all electricity produced
in the United States. It's also used as a basic energy source in many
industries, including, steel, cement and paper.
THERE'S PLENTY OF IT and IT'S AVAILABLE
Many U.S. coal beds are very near the ground's surface. Modern mining
methods allow us to easily reach most of our coal reserves.
ITS EFFECT ON THE ENVIRONMENT
Environmental issues, such as clean water and clean air, will determine
the future of coal.
COAL PRODUCTION
Coal production provides thousands of jobs in all aspects of the coal
industry - exploration, reclamation, mining, equipment supply, and
transportation.
4 MAJOR USES
FOR ELECTRIC POWER
Power plants burn coal to make steam. The steam turns turbines which
generate electricity. Electric utility companies use over 80% of the
coal mined in the United States.
FOR INDUSTRY
A variety of industries use coal's heat and by-products. Separated
ingredients of coal (such as methanol and ethylene) are used in making
plastics, tar, synthetic fibers, fertilizers, and medicines. The concrete
and paper industries also burn large amounts of coal. Industrial consumers
use over six percent of the coal mined in the United States.
FOR MAKING STEEL
Coal is baked in hot furnaces to make coke, which is used to smelt
iron ore into iron needed for making steel. It is the very high temperatures
created from the use of coke that gives steel the strength and versatility
for products such as bridges, buildings, and automobiles.
FOR EXPORT
The United States is the world's 4th largest coal exporter. Approximately
60 million tons are exported every year to about 40 different countries
worldwide. Most trade is with Western Europe, Canada and Brazil.
