4Energy Resource Transition During the 20th century, worldwide use of energy resources shifted dramatically:COAL: % to 22%OIL: % to 30%NATURAL GAS 1% to 23%NUCLEAR % to 6%RENEWABLE % to 19%
5WHAT IS ENERGYWork - Application of force through a distance.Energy - The capacity to do work.Power - Rate at which work is done.Calorie - Amount of energy necessary to heat 1 gram of water 1o C.Joule - Amount of work done when a force of 1 newton is exerted over 1 meter.
6Energy HistoryFire probably first human energy technology.Muscle power provided by domestic animals has been important since dawn of agriculture 10,000 years ago.Wind and water power used nearly as long.Coal replaced wood at beginning of 19th century.Oil replaced coal in 20th century.
7Current Energy Sources Fossil fuels currently provide about 86% of all commercial energy in the world.Hydroelectric dams supply about 7% of commercial power.Nuclear power makes up about 7% of commercial power.
9Per Capita Consumption Richest countries have consumed nearly 80% of all commercial energy. This is changing.On average, each person in the U.S. and Canada uses more than 300 GJ of energy annually.In poorest countries of the world, each person generally consumes less than one GJ annually.
12HOW ENERGY IS USEDLargest share of energy used in the U.S. is consumed by industry (33%).Residential and Commercial buildings use 20% of primary energy consumed in U.S..Transportation consumes about 27% of all energy used in the U.S..Three trillion passenger miles and 600 billion ton miles of freight carried annually by motor vehicles in the U.S..
13How Energy Is UsedAbout half of all energy in primary fuels is lost during conversion to more useful forms while being shipped, or during use.Nearly two-thirds of energy in coal being burned to generate electricity is lost during thermal conversion in the power plant.Another 10% is lost during transmission and stepping down to household voltages.
14COALFossilized plant material preserved by burial in sediments and compacted and condensed by geological forces into carbon-rich fuel.Most laid down during Carboniferous period (286 million to 360 million years ago).
15Coal-Coal replaced wood in the 18th century in the western world and supplied the energy for the steam engine and the Industrial Revolution.23.5% of the world’s energy is provided by coal worldwide; this number is steadily increasing due to China’s-Coal power plants provide over half of the nations’ electricity.-The US used over 1 billion tons of coal in 2005
16ReservesProven reserves- have been identified, mapped, measured, and shown to be economically recoverable.Known reserves -have been identified but not thoroughly mapped.World total resource is estimated to be 10 trillion metric tons. (several thousand years’ supply)Known US reserves are 266 billion tons.
17CoalResources and ReservesWorld coal deposits are ten times greater than conventional oil and gas resources combined.Under current consumption rates, this could last several thousand years.
19Environmental Issues Coal contains 10% sulfur (by weight) Toxic metals- uranium, arsenic, lead, cadmium, mercury, rubidium, thallium, and zinc.These were absorbed by plants and concentrated in the process of coal formation, released when burned.25% of all atmospheric mercuryOxidizes nitrogen compoundsReleases carbon dioxide-1/2 of industrial carbon dioxideUnderground mines-poisonous or explosive gases. (Black lung disease)
20CoalMiningBetween 1870 and 1950, more than 30,000 coal miners died of accidents and injuries in Pennsylvania alone.Several thousands have died of respiratory diseases.Black Lung Disease - Inflammation and fibrosis caused by accumulation of coal dust in the lungs or airways.
21CoalAir PollutionCoal burning releases radioactivity and toxic metals into the atmosphere.Coal combustion is responsible for 25% of all atmospheric mercury pollution in the U.S..Coal contains up to 10% sulfur by weight.Unless removed by washing or flue-gas scrubbing, sulfur is released and oxidizes to sulfur dioxide or sulfate.
22-The 3 major coal producing states are Wyoming, West Virginia, and Kentucky -There are three types of coal:1. Lignite -youngest coal, lowest carbon content, brown coal, mainly used for electric power generation.2. Bituminous - the most plentiful form of coal in the US. Higher carbon content than lignite and will burn much hotter. Primarily used to generate electricity and make coke for the steel industry.
233. Anthracite -highest carbon content and hottest when burned 3. Anthracite -highest carbon content and hottest when burned. There are 7.3 billion tons of anthracite reserves in the US.-Other products made from coal are:1. Perfumes2. Fingernail polish3. Briquettes4. Insecticides5. Disinfectants6. Antiseptics7. Dyes
25The Earth at Night-main use for coal is production of electricity.
26Fossil fuel –composed of prehistoric marine plants & animals Petroleum-oilFossil fuel –composed of prehistoric marine plants & animalsOil was first discovered in the US in 1859.At the beginning of the 20th century, oil supplied only 4% of the world’s energy.
27Today oil supplies about 40% of the world’s energy. The US imports over 60% of the oil we use.95% of the energy for transportation in the US comes from oil.Each day US consumers use about 850 million gallons of oil.40% of the petroleum is produced domestically by 500,000 oil wells
28There are 132 refineries in the US that turn the oil into useful products. 45% of crude oil is refined into gasoline for use in cars -370 millions gallons/day.It takes over 42,000 daily trips to transport fuel to over 170,000 service stations across the US (one delivery every 2 seconds )
34The top sources of US crude oil imports for December were: (as of 12/06) 1. Canada (1.829 million barrels/day)2. Saudi Arabia (1.471 million barrels/ day)3. Mexico (1.245 million barrels/ day)4. Venezuela (1.045 million barrels/ day),5.Nigeria (1.010 million barrels per day).6.Angola (0.610 million barrels/ day)7. Algeria (0.421 million barrels/ day)8. Iraq (0.419 million barrels/ day)9. Ecuador (0.254 million barrel/day)10. Kuwait (0.163 million barrels/day).
42OILResources and ReservesTotal amount of oil in the world is estimated at 4 trillion barrels. (Half is thought to be ultimately recoverable)In 2005, proven reserves were estimated at 1 trillion barrels.As oil becomes depleted and prices rise, it will likely become more economical to find and bring other deposits to market.
44NATURAL GASWorld’s third largest commercial fuel.23% of global energy consumption.Produces half as much CO2 as equivalent amount of coal.Most rapidly growing energy source.Difficult to ship long distances, and to store in large quantities.
45Natural GasResources and ReservesProven world reserves of natural gas are 5,500 trillion ft3.Current reserves represent roughly 60 year supply at present usage rates.Proven reserves in North America are about 250 trillion ft3.
47Unconventional Gas Sources Methane hydrate - Small individual molecules of natural gas trapped in a crystalline matrix of frozen water.Thought to hold 10,000 gigatons of carbon, or twice as much as combined amount of all traditional fossil fuels combined.Difficult to extract, store, and ship.
48NUCLEAR POWERPresident Dwight Eisenhower, 1953, “Atoms for Peace”speech.Nuclear-powered electrical generators would provide power “too cheap to meter.”Between 1970 and 1974, American utilities ordered 140 new reactors for power plants.
49Nuclear PowerAfter 1975, only 13 orders were placed for new nuclear reactors, and all of those were subsequently cancelled.In all, 100 of 140 reactors on order in 1975 were cancelled.Electricity from nuclear power plants was about half the price of coal in 1970, but twice as much in 1990.
51How Do Nuclear Reactors Work ? Most commonly used fuel is U235, a naturally occurring radioactive isotope of uranium.Occurs naturally at 0.7% of uranium, but must be enriched to about of 3%.Formed in cylindrical pellets (1.5 cm long) and stacked in hollow metal rods (4 m long).About 100 rods are bundled together to make a fuel assembly.Thousands of fuel assemblies bundled in reactor core.
52How Do Nuclear Reactors Work When struck by neutrons, radioactive uranium atoms undergo nuclear fission, releasing energy and more neutrons.Triggers nuclear chain reaction.
54How Do Nuclear Reactors Work Reaction is moderated in a power plant by neutron-absorbing solution (Moderator).In addition, Control Rods composed of neutron-absorbing material are inserted into spaces between fuel assemblies to control reaction rate.Water or other coolant is circulated between the fuel rods to remove excess heat.
55Kinds of ReactorsSeventy percent of nuclear power plants are pressurized water reactors.Water circulated through core to absorb heat from fuel rods.Pumped to steam generator where it heats a secondary loop.Steam from secondary loop drives high-speed turbine producing electricity.
56Kinds of ReactorsBoth reactor vessel and steam generator are housed in a special containment building preventing radiation from escaping, and providing extra security in case of accidents.Under normal operating conditions, a PWR releases very little radioactivity.
58Kinds of ReactorsSimpler, but more dangerous design is a boiling water reactor.Water from core boils to make steam, directly driving turbine generators.Highly radioactive water and steam leave containment structure.Canadian deuterium reactors - Operate with natural, un-concentrated uranium.Graphite moderator reactors - Operate with a solid moderator instead of a liquid.
59Alternative Reactor Designs High-Temperature, Gas-Cooled ReactorsUranium encased in tiny ceramic-coated pellets.Process-Inherent Ultimate Safety ReactorsReactor core submerged in large pool of boron-containing water within a massive pressure vessel.
60Breeder ReactorsBreeder reactors create fissionable plutonium and thorium isotopes from stable forms of uranium.Uses plutonium reclaimed from spent fuel from conventional fission reactors as starting material.
62Breeder Reactor Drawbacks Reactor core must be at very high density, thus liquid sodium used as a coolant.Corrosive and difficult to handle.Core will self-destruct within a few seconds if primary coolant is lost.Produces weapons-grade plutonium.
63RADIOACTIVE WASTE MANAGEMENT Until 1970, the U.S., Britain, France, and Japan disposed of radioactive waste in the ocean.Production of 1,000 tons of uranium fuel typically generates 100,000 tons of tailings and 3.5 million liters of liquid waste.Now approximately 200 million tons of radioactive waste in piles around mines and processing plants in the U.S..
64Radioactive Waste Management About 100,000 tons of low-level waste (clothing) and about 15,000 tons of high-level (spent-fuel) waste in the U.S..For past 20 years, spent fuel assemblies have been stored in deep water-filled pools at the power plants. (Designed to be temporary)Many internal pools are now filled and a number plants are storing nuclear waste in metal dry casks outside.
65Radioactive Waste Management U.S. Department of Energy announced plans to build a high-level waste repository near Yucca Mountain Nevada in 1987.Facility may cost between $10 and 35 billion, and will not open until at least 2010.
66Decommissioning Old Nuclear Plants Most plants are designed for a 30 year operating life.Only a few plants have thus far been decommissioned.General estimates are costs will be 2-10 times more than original construction costs.
67CHANGING FORTUNES OF NUCLEAR POWER Public opinion has fluctuated over the years.When Chernobyl exploded in 1985, less than one-third of Americans favored nuclear power.Now, half of all Americans support nuclear-energy.Currently, 103 nuclear reactors produce about 20% of all electricity consumed in the U.S..
68Changing FortunesWith natural gas prices soaring, and electrical shortages looming, many sectors are once again promoting nuclear reactors.Over the past 50 years, the U.S. government has provided $150 billion in nuclear subsidies, but less than $5 billion to renewable energy research.
69NUCLEAR FUSIONNuclear Fusion - Energy released when two smaller atomic nuclei fuse into one large nucleus. (Sun)Temperatures must be raised to 100,000,000o C and pressure must reach several billion atmospheres.Magnetic ConfinementInertial ConfinementDespite 50 years and $25 billion, fusion reactors have never produced more energy than they consume.