Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Conventional Energy Chapter 21

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Outline: Energy History How Energy Is Used Coal Oil Natural Gas Nuclear Power  Fission  Reactors  Waste Management  Fusion

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. WHAT IS ENERGY Work - 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 1 o C.  Joule - Amount of work done when a force of 1 newton is exerted over 1 meter.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Energy History Muscle power provided by domestic animals has been important since dawn of agriculture 10,000 years ago. World Oil Use peaked in  Oil prices rose ten-fold in 1970’s. Early 1980’s saw increased interest in conservation and renewable energy.  Oil glut in mid 1980’s caused prices to fall. US now imports over half annual oil supply.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Current Energy Sources Fossil Fuels currently provide about 85% of all commercial energy in the world.  Biomass fuels contribute about 6% of commercial energy.  Other renewable sources make up 4-5% of commercial power.  Nuclear power makes up 4-5% of commercial power.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Worldwide Commercial Energy Production

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Per Capita Consumption Richest 20 countries consume nearly 80% of natural gas, 65% of oil, and 50% of coal production annually.  On average, each person in the US 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.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Per Capita Energy Use and GNP

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. HOW ENERGY IS USED Largest share of energy used in the US is consumed by industry (36.5%). Residential and Commercial buildings use 34% of primary energy consumed in US. Transportation consumes about 26% of all energy used in the US.  Three trillion passenger miles and 600 billion ton miles of freight carried annually by motor vehicles in the US.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. How Energy Is Used About 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.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. COAL Fossilized 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).

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Coal Resources and Reserves  World coal deposits are ten times greater than conventional oil and gas resources combined. - Under current consumption rates, this could last several thousand years.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Proven-In-Place Coal Reserves

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Coal Mining  Between 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.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Coal Air Pollution  Coal burning releases radioactivity and toxic metals into the atmosphere. - Coal combustion is responsible for 25% of all atmospheric mercury pollution in the US.  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.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. OIL Petroleum is formed very similar to oil - Organic material buried in sediment and subjected to high pressure and temperature.  Oil Pool usually composed of individual droplets or thin film permeating spaces in porous sandstone or limestone. - At least half of total deposit is usually uneconomical to pump out.  Secondary oil recovery techniques.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Oil Recovery Process

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. OIL Resources and Reserves  Total amount of oil in the world is estimated at 4 trillion barrels. (Half is thought to be ultimately recoverable) - In 1999, 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.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Proven Recoverable Oil Reserves

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Oil Imports and Domestic Supplies  The US has used about 40% of its original recoverable petroleum resource. - Of the 120 billion barrels thought to remain, 58 billion are proven-in-place.  Until 1947, the US was the world’s leading oil export country. - By 1998, the US was importing 10 million barrels per day - Half of total consumption.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Oil Oil Shales and Tar Sands  Estimates of total oil supply usually do not reflect large potential from unconventional oil sources such as shale oil and tar sand. - Could potentially double total reserve.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. NATURAL GAS World’s third largest commercial fuel.  23% of global energy consumption.  Produces half as much CO 2 as equivalent amount of coal.  Most rapidly growing energy source. - Difficult to ship long distances, and to store in large quantities.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Natural Gas Resources and Reserves  Proven world reserves of natural gas are 3,200 trillion cubic feet. - Current reserves represent roughly 60 year supply at present usage rates.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Proven-In-Place Natural Gas Reserves

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Unconventional 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.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. NUCLEAR POWER President 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.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Nuclear Power After 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.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Nuclear Power Plant History

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. How Do Nuclear Reactors Work Most commonly used fuel is U 235, 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 and bundled together to make a fuel assembly. - Thousands of fuel assemblies bundled in reactor core.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. How Do Nuclear Reactors Work When struck by neutrons, radioactive uranium atoms undergo nuclear fission, releasing energy and more neutrons.  Triggers nuclear chain reaction.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Nuclear Fission

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. How 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.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Kinds of Reactors Seventy 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.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Kinds of Reactors Both 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.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. PWR

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Kinds of Reactors Simpler, 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.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Alternative Reactor Designs High-Temperature, Gas-Cooled Reactors  Uranium encased in tiny ceramic-coated pellets. Process-Inherent Ultimate Safety Reactors  Reactor core submerged in large pool of boron-containing water within a massive pressure vessel.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Breeder Reactors Breeder 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.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Breeder Reactors

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Breeder 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.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. RADIOACTIVE WASTE MANAGEMENT Until 1970, the US, 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 US.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Radioactive Waste Management About 100,000 tons of low-level waste (clothing) and about 15,000 tons of high-level (spent-fuel) waste in the US.  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.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Radioactive Waste Management US Department of Energy announced plans to build a high-level waste repository near Yucca Mountain Nevada in  Facility may cost between $10 and 35 billion, and will not open until at least 2010.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Decommissioning 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.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. CHANGING FORTUNES 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 US.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Changing Fortunes With natural gas prices soaring, and electrical shortages looming, many sectors are once again promoting nuclear reactors.  Over the past 50 years, the US government has provided $150 billion in nuclear subsidies, but less than $5 billion to renewable energy research.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. NUCLEAR FUSION Nuclear Fusion - Energy released when two smaller atomic nuclei fuse into one large nucleus. (Sun)  Temperatures must be raised to 100,000,000 o C and pressure must reach several billion atmospheres. - Magnetic Confinement - Inertial Confinement  Despite 50 years and $25 billion, fusion reactors have never produced more energy than they consume.

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Summary: Energy History How Energy Is Used Coal Oil Natural Gas Nuclear Power  Fission  Reactors  Waste Management  Fusion

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed.