27 Nisan 2013 Cumartesi

Non-Renewable Sources Overview

Non-Renewable Sources Overview

Energy sources are considered nonrenewable if they cannot be replenished (made again) in a short period of time. On the other hand, renewable energy sources such as solar and wind can be replenished naturally in a short period of time.
Nonrenewable energy sources come out of the ground as liquids, gases, and solids. Crude oil (petroleum) is the only commercial nonrenewable fuel that is naturally in liquid form. Natural gas and propane are normally gases, and coal is a solid. Of the four categories of nonrenewable source listed below, only the first three are fossil fuels. Uranium ore, a solid, is mined and converted to a fuel used at nuclear power plants. Uranium is not a fossil fuel, but is a nonrenewable fuel.
The four nonrenewable energy sources used most often are listed here. Click on one to learn about it.

Oil and Petroleum Products

Oil was formed from the remains of animals and plants (diatoms) that lived millions of years ago in a marine (water) environment before the dinosaurs. Over millions of years, the remains of these animals and plants were covered by layers of sand and silt. 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."
A 42-U.S. gallon barrel of crude oil yields between 44 and 45 gallons of petroleum products.
Refineries in the United States produce about 19 gallons of gasoline from every 42-gallon barrel of crude oil that is refined.
U.S. Gasoline in History
Edwin Drake dug the first U.S. oil well in 1859 and distilled the petroleum to produce kerosene for lighting. Drake had no use for the gasoline or other products, so he discarded them. It wasn't until 1892 with the invention of the automobile that gasoline was recognized as a valuable fuel. By 1920, there were 9 million vehicles on the road powered by gasoline, and service stations were popping up everywhere.
249 Million Vehicles on the Road
Today, gasoline is the fuel used by most passenger vehicles in the United States. There are about 249 million vehicles that use gasoline, and they each travel over 12,000 miles per year. There are about 162,000 fueling stations that provide convenient refueling for consumers. Nearly two-thirds of fuel used for transportation is in the form of gasoline.
The U.S. Uses More than it Makes
Gasoline is the primary transportation fuel used in the United States. Americans use about 380 million gallons of gasoline every day. With about 304 million people in the United States, that equals more than a gallon of gasoline every day for each man, woman, and child. The United States does not produce enough crude oil to make all of the gasoline used by U.S. motorists. Only about 34% of the crude oil used by U.S. refineries is produced in the United States. The rest is imported from other countries.
Gasoline Use Contributes to Air and Water Pollution
Burning gasoline produces carbon dioxide, a major greenhouse gas. Scientists know with virtual certainty that increasing greenhouse gas concentrations tend to warm the planet.
Gasoline is a highly flammable and toxic liquid. The vapors given off when it evaporates and the substances produced when it is burned (carbon monoxide, nitrogen oxides, particulate matter, and unburned hydrocarbons) contribute to air pollution.
Laws Such as the Clean Air Act Reduce Environmental Impact
The Clean Air Act is the major law aimed at reducing air pollution. The Clean Air Act (first passed in 1970) and its amendments have aimed to reduce pollution from driving by requiring both cleaner cars and cleaner fuels (gasoline and diesel). The Environmental Protection Agency (EPA) put these goals into action by requiring the following:
  • Removal of leaded gasoline in 1996
  • Cleaner reformulated gasoline required since 1995
  • Low sulfur gasoline, reduced by 90% beginning in 2006
  • Reduced risk of gasoline leaks by requiring double-lined storage tanks in 1990
Gasoline Changes with the Seasons
The main difference between winter- and summer-grade gasoline is its vapor pressure. Gasoline evaporates more easily in warm weather, releasing more volatile organic compounds that contribute to health problems and the formation of ground-level ozone and smog. In order to cut down on pollution, the Environmental Protection Agency requires petroleum refiners to reduce the vapor pressure of gasoline used during the summer months. During cold winter months, vapor pressure must be high enough for the engine to start easily.
Heating oil and diesel fuel are closely related products called distillates. Approximately 12 gallons of distillate are produced from each 42-gallon barrel of crude oil. Of these 12 gallons of distillate, less than 2 gallons are heating oil, and the other 10 are diesel fuel.
Diesel fuel is used in the diesel engines found in most freight trucks, trains, buses, boats, and farm and construction vehicles. Diesel fuel powers the vehicles that we use to produce and transport nearly all of our food and all of the other products we make and buy. Some cars and small trucks and boats also have diesel engines.
Diesel fuel is also used in diesel engine-generators to generate electricity. Many industrial facilities, large buildings, institutional facilities, hospitals, and electric utilities have diesel generators for backup and emergency power supply. Most remote villages in Alaska use diesel generators for their electricity.
Approximately 11 gallons of distillate are produced from each 42-gallon barrel of crude oil. Of these 11 gallons of distillate, less than 2 gallons are heating oil, and the other 9 are diesel fuel. Because diesel fuel requires additional processing to remove sulfur, it is more costly to produce than heating oil. Heating oil is used by many Americans, especially in the Northeast, to heat their homes.
Chemical Diagram of Propane C3H8
Propane is an energy-rich gas, C3H8. It is one of the liquefied petroleum gases (LP-gases or LPGs) that are found mixed with natural gas and oil. Propane and other liquefied gases, including ethane and butane, are separated from natural gas at natural gas processing plants, or from crude oil at refineries. The amount of propane produced from natural gas and from oil is roughly equal.
Propane naturally occurs as a gas. However, at higher pressure or lower temperatures, it becomes a liquid. Because propane is 270 times more compact as a liquid than as a gas, it is transported and stored in its liquid state. Propane becomes a gas again when a valve is opened to release it from its pressurized container. When returned to normal pressure, propane becomes a gas so that we can use it.
How Is Propane Used?
Although propane accounts for less than 2% of all energy used in the United States, it has some very important uses. Propane is the most common source of energy in rural areas that do not have natural gas service.
In homes, propane is used for:
  • Heating homes
  • Heating water
  • Cooking and refrigerating food
  • Drying clothes
  • Fueling gas fireplaces and barbecue grills
On farms, propane is used to dry corn and power farm equipment and irrigation pumps. Businesses and industry use propane to run their fork lifts and other equipment.
While only a small fraction of propane is used for transportation, it is the second largest alternative transportation fuel in use today. Instead of gasoline, propane often fuels fleets of vehicles used by school districts, government agencies, and taxicab companies. In recreational pursuits, hot air balloons use propane to heat the air that makes them rise.
Did You Know?
About 45% of propane is used by the chemical industry as a raw material for making plastics, nylon, and other materials.

back to top
About 24% of energy used in the United States came from natural gas in 2008. The United States used 23.8 trillion cubic feet (Tcf) of natural gas, matching the record high set in 2000.
How Natural Gas Is Used
Natural gas is used to produce steel, glass, paper, clothing, brick, electricity and as an essential raw material for many common products. Some products that use natural gas as a raw material are: paints, fertilizer, plastics, antifreeze, dyes, photographic film, medicines, and explosives.
Slightly more than half of the homes in the United States use natural gas as their main heating fuel. Natural gas is also used in homes to fuel stoves, water heaters, clothes dryers, and other household appliances.
The major consumers of natural gas in the United States in 2008 included:
  • Electric power sector - 6.7 trillion cubic feet (Tcf)
  • Industrial sector - 7.9 Tcf
  • Residential sector - 4.9 Tcf
  • Commercial sector - 3.1 Tcf
Where Natural Gas Is Used
Natural gas is used throughout the United States, but the top natural gas consuming States in 2007 were:
  • Texas
  • California
  • Louisiana
  • New York
  • Illinois
  • Florida

Map of Gas Production in Conventional Fields (Lower 48 states)

  View/Download/Print a PDF version of Map (2.8 megs)

Map of Active Shale Gas Plays (Lower 48 states)

  View/Download/Print a PDF version of Map (1.5 megs)

back to top


Coal is a combustible black or brownish-black sedimentary rock composed mostly of carbon and hydrocarbons. It is the most abundant fossil fuel produced in the United States.
Coal is a nonrenewable energy source because it takes millions of years to create. The energy in coal comes from the energy stored by plants that lived hundreds of millions of years ago, when the Earth was partly covered with swampy forests.
For millions of years, a layer of dead plants at the bottom of the swamps was covered by layers of water and dirt, trapping the energy of the dead plants. The heat and pressure from the top layers helped the plant remains turn into what we today call coal.
Types of Coal
Coal is classified into four main types, or ranks (anthracite, bituminous, subbituminous, and lignite), depending on the amounts and types of carbon it contains and on the amount of heat energy it can produce. The rank of a deposit of coal depends on the pressure and heat acting on the plant debris as it sank deeper and deeper over millions of years. For the most part, the higher ranks of coal contain more heat-producing energy.
Anthracite contains 86-97% carbon, and generally has a heating value slightly higher than bituminous coal. It accounts for less than 0.5% of the coal mined in the United States.
All of the anthracite mines in the United States are located in northeastern Pennsylvania.
Bituminous coal contains 45-86% carbon. Bituminous coal was formed under high heat and pressure. Bituminous coal in the United States is between 100 to 300 million years old. It is the most abundant rank of coal found in the United States, accounting for about half of U.S. coal production. Bituminous coal is used to generate electricity and is an important fuel and raw material for the steel and iron industries.
West Virginia, Kentucky, and Pennsylvania are the largest producers of bituminous coal.
Subbituminous coal has a lower heating value than bituminous coal. Subbituminous coal typically contains 35-45% carbon. Most subbituminous coal in the United States is at least 100 million years old. About 46% of the coal produced in the United States is subbituminous.
Wyoming is the leading source of subbituminous coal.
Lignite is the lowest rank of coal with the lowest energy content. Lignite coal deposits tend to be relatively young coal deposits that were not subjected to extreme heat or pressure, containing 25%-35% carbon. Lignite is crumbly and has high moisture content. There are 19 lignite mines in the United States, producing about 7% of U.S. coal.
Most lignite is mined in Texas and North Dakota. Lignite is mainly burned at power plants to generate electricity.
During nuclear fission, a small particle called a neutron hits the uranium atom and splits it, releasing a great amount of energy as heat and radiation. More neutrons are also released. These neutrons go on to bombard other uranium atoms, and the process repeats itself over and over again. This is called a chain reaction. The heat given off during fission in the reactor is used to boil water into steam, which turns turbine blades. As they turn, they drive generators that make electricity.
Drawing of How Fission Splits the Uranium Atom


back to top

Nuclear Energy

Nuclear energy is energy in the nucleus (core) of an atom. Atoms are tiny particles that make up every object in the universe. There is enormous energy in the bonds that hold atoms together.
In nuclear fission, atoms are split apart to form smaller atoms, releasing energy. Nuclear power plants use this energy to produce electricity. Nuclear power accounted for about 20% of the total electricity generated in the United States in 2008, about 8% of the total U.S. energy consumed from all sources.
Nuclear Fuel - Uranium
The fuel most widely used by nuclear plants for nuclear fission is a certain kind of uranium, referred to as U-235. This kind of uranium is used as fuel because its atoms are easily split apart. Though uranium is quite common, about 100 times more common than silver, U-235 is relatively rare.
Most U.S. uranium is mined in the West. Once uranium is mined, the U-235 must be extracted and processed before it can be used as a fuel.
Nuclear Energy Produces Radioactive Waste
The spent fuel is highly radioactive. Like all radioactive materials, it is hazardous. Since a power plant will generate about 20 metric tons of spent fuel each year, finding ways to isolate this waste so that it does no harm is a critical consideration.
Some canisters are designed to be placed vertically in robust above-ground concrete or steel structures.
Dry Storage Cask

Source: U.S. Nuclear Regulatory Commission
Some canisters are designed to be stored horizontally in above-ground concrete bunkers, each of which is about the size of a one-car garage.

Source: U.S. Nuclear Regulatory Commission
The United States Has the Most Nuclear Capacity
In 2007, the United States had more nuclear capacity than any other nation, 100.3 gigawatts, followed in rank order by France, Japan, and Germany. Although each of these countries generates less electricity than the United States, they are more dependent on nuclear power.
International Outlook for Nuclear Power Varies
International growth in commercial nuclear power has slowed, but several countries have ambitious nuclear construction programs. The United States, China, India, Russia, South Korea, and other countries have brought new reactors into service during the latter part of the twentieth century. However, the United States has not ordered any new reactors since 1978.
back to top

Hiç yorum yok:

Yorum Gönder