Fossil Fuels I

What are Fossil Fuels? All fossil fuels are forms of stored solar energy that are created from incomplete biological decomposition. Fossil non-renewable fuels include: Coal Oil Natural gas

Sources of Energy Used by Humans

Fossil Fuels Predominant Energy Source Nuclear ~ 6% Hydroelectric ~ 4% Biomass fuels < 5% Alternatives ~1%

20% of the World’s Population Consumes 68% of the World’s Energy.

What is the difference between US/Canada and Switzerland/Japan/Denmark in energy use?

Where Energy Goes in the U.S.A. Industry ~ 42% Making metals; chemical industry (plastics, fertilizers) Residential/commercial ~ 33% Heating, air conditioning, lighting, and hot water Transportation ~ 25% Passenger travel, hauling by semi (Trains, barges, ships and pipelines use 12% of fuel, yet haul 75% of freight.

Where Energy Goes in the U.S.A.

Oil and Gas was Formed by Partial Decomposition of Aquatic Organisms

OIL Location - usually in porous and coarse-grained stone such as sandstone and limestone. Requires a trap - rock, like shale, that impedes the hydrocarbons in anticlines (arch-shaped folds).

Oil Extraction: Primary Recovery (~25%) - oil is under pressure, so pumping oil is a way to control the extraction of oil. Secondary Recovery (>50%) - injecting steam, water, or chemicals (carbon dioxide, nitrogen)

World Gas and Crude Oil Reserves Natural Gas Crude Oil

Known Oil Reserves 60% of proven recoverable oil reserves in the Mid-East. Proven reserves of oil = 1 trillion barrels At 22 billion barrels a year (present rate), this is 45 years worth of oil.

Uses of Oil

Environmental Effects of Oil and Gas Use Carbon Dioxide Release Water Contamination Pollution of marine waters from leaks or spills. Wastewater used in secondary recovery. Pollution of surface waters and groundwater from runoff and leaking from broken pipes and storage tanks. Spills Gulf war = 250 million gallons Exxon Valdez = 11 million gallons

Environmental Effects of Oil and Gas Use Soil Contamination From wells, pipelines, storage tanks, and roads Release of drilling mud

Smoke tornado

ANWR = 200 day supply of oil?

What are the Costs and Benefits of Exploring the ANWR for Oil?

Natural Gas Formation similar to oil, from partially decomposed aquatic organisms subjected to heat and pressure. In contrast to oil which consists of a mixture of often hundreds of hydrocarbons, natural gas is composed primarily of one hydrocarbon – methane. Natural gas is more expense to transport than oil, and it is often burned off at an oil well as waste.

Advantages of Natural Gas Compared to oil products, natural gas produces about 80-90% fewer emission when used in vehicles. Natural gas can be used for both heating and cooling systems. Natural gas is more plentiful than oil.

Coal Coal was formed by the partial decay of plants and animals. Under heat and pressure from burial by later material, the partially decomposed plant material became the carbon-rich rock we call coal. Coal may be classified as lignite, bituminous, or anthracite according to its hardness. Anthracite, the hardest, was formed under the highest temperatures and produces the fewest pollutants when burned.

Carboniferous forests from which coal was formed

Coal Composition Formation - 300 million years ago Kinds:: Anthracite - hard coal, shiny, blue/black coal. Highest heat producing capacity of the coals. Lowest volatiles. Bituminous - called soft coal, but is hard, bright black coal - usually high in sulfur volatiles. Lignite - soft, moist coal which produces little heat compared to other coals. Coal Composition

Coal Extraction

Extraction - Strip mines 1. Bulldozers and scrapers remove the vegetation and topsoil from an area. 2. Soil is stockpiled for reuse. 3. Overburden (rock over the coal) is removed. 4. Coal beds are drilled and blasted and loaded. 5. The cut is filled and topsoil is replaced. Surface Mining Control and Reclamation Act 1977 Prior to this, land did not have to be re-established.

World coal deposits are vast (10x greater than oil), and reserves could last for more than 200 years

Environmental Effects of Coal Mining Carbon dioxide release Sulfur dioxide and nitrogen oxide release - leads to acid precipitation Mine acid drainage - acidifies streams; toxic metals introduced into streams Release of radioactivity and toxic metals

Environmental Effects of Coal Mining Land disturbance Other human risks: Black lung disease Cave-ins Coal fires

Acid Deposition Problems

Ways to Alleviate Pollution Chemical or physical cleaning of coal prior to combustion. Boiler designs that require a lower temperature of combustion, reducing emissions of nitrogen oxides. Fluidized Bed Combustion - Injection of material rich in calcium carbonate while burning. Reacts with sulfur dioxide, producing a calcium sulfate sludge. Scrubbing/Filter/Precipitator following burning.

Fluidized Bed Combustion - Limestone captures sulfur and nitrogen impurities in slag, decreasing pollutants in the air.

Scrubber Electrostatic Precipitator Fabric Filter

Reserves at Present Rate of Consumption: Oil: 45 years Coal: 200 years But will energy consumption level out?

NUCLEAR ENERGY When isotopes of uranium and plutonium undergo controlled nuclear fission, the resulting heat produces steam that spins turbines to generate electricity. The uranium oxide consists of about 97% nonfissionable uranium-238 and 3% fissionable uranium-235. The concentration of uranium-235 is increased through an enrichment process.

Small amounts of radioactive gases Uranium fuel input (reactor core) Control rods Containment shell Heat exchanger Steam Turbine Generator Electric power Waste heat Hot coolant Useful energy 25%–30% Hot water output Pump Pump Coolant Pump Pump Cool water input Waste heat Figure 16.16 Science: light-water–moderated and –cooled nuclear power plant with a pressurized water reactor. QUESTION: How does this plant differ from the coal-burning plant in Figure 16-13? Moderator Coolant passage Shielding Pressure vessel Water Condenser Periodic removal and storage of radioactive wastes and spent fuel assemblies Periodic removal and storage of radioactive liquid wastes Water source (river, lake, ocean) Fig. 16-16, p. 372

NUCLEAR ENERGY After three or four years in a reactor, spent fuel rods are removed and stored in a deep pool of water contained in a steel-lined concrete container. Figure 16-17

NUCLEAR ENERGY After spent fuel rods are cooled considerably, they are sometimes moved to dry-storage containers made of steel or concrete. Figure 16-17

Decommissioning of reactor Fuel assemblies Enrichment of UF6 Fuel fabrication (conversion of enriched UF6 to UO2 and fabrication of fuel assemblies) Temporary storage of spent fuel assemblies underwater or in dry casks Conversion of U3O8 to UF6 Uranium-235 as UF6 Plutonium-239 as PuO2 Spent fuel reprocessing Low-level radiation with long half-life Figure 16.18 Science: the nuclear fuel cycle. QUESTION: Are any parts of the nuclear fuel cycle within 27 kilometers (17 miles) of where you live or go to school? Geologic disposal of moderate & high-level radioactive wastes Open fuel cycle today “Closed” end fuel cycle Fig. 16-18, p. 373

What Happened to Nuclear Power? After more than 50 years of development and enormous government subsidies, nuclear power has not lived up to its promise because: Multi billion-dollar construction costs. Higher operation costs and more malfunctions than expected. Poor management. Public concerns about safety and stricter government safety regulations.

Case Study: The Chernobyl Nuclear Power Plant Accident The world’s worst nuclear power plant accident occurred in 1986 in Ukraine. The disaster was caused by poor reactor design and human error. By 2005, 56 people had died from radiation released. 4,000 more are expected from thyroid cancer and leukemia.

NUCLEAR ENERGY In 1995, the World Bank said nuclear power is too costly and risky. In 2006, it was found that several U.S. reactors were leaking radioactive tritium into groundwater. Figure 16-19

NUCLEAR ENERGY A 1,000 megawatt nuclear plant is refueled once a year, whereas a coal plant requires 80 rail cars a day. Figure 16-20

NUCLEAR ENERGY Terrorists could attack nuclear power plants, especially poorly protected pools and casks that store spent nuclear fuel rods. Terrorists could wrap explosives around small amounts of radioactive materials that are fairly easy to get, detonate such bombs, and contaminate large areas for decades.

NUCLEAR ENERGY When a nuclear reactor reaches the end of its useful life, its highly radioactive materials must be kept from reaching the environment for thousands of years. At least 228 large commercial reactors worldwide (20 in the U.S.) are scheduled for retirement by 2012. Many reactors are applying to extent their 40-year license to 60 years. Aging reactors are subject to embrittlement and corrosion.

NUCLEAR ENERGY Building more nuclear power plants will not lessen dependence on imported oil and will not reduce CO2 emissions as much as other alternatives. The nuclear fuel cycle contributes to CO2 emissions. Wind turbines, solar cells, geothermal energy, and hydrogen contributes much less to CO2 emissions.

NUCLEAR ENERGY Scientists disagree about the best methods for long-term storage of high-level radioactive waste: Bury it deep underground. Shoot it into space. Bury it in the Antarctic ice sheet. Bury it in the deep-ocean floor that is geologically stable. Change it into harmless or less harmful isotopes.

New and Safer Reactors Pebble bed modular reactor (PBMR) are smaller reactors that minimize the chances of runaway chain reactions. Figure 16-21

New and Safer Reactors Some oppose the pebble reactor due to : A crack in the reactor could release radioactivity. The design has been rejected by UK and Germany for safety reasons. Lack of containment shell would make it easier for terrorists to blow it up or steal radioactive material. Creates higher amount of nuclear waste and increases waste storage expenses.

NUCLEAR ENERGY Nuclear fusion is a nuclear change in which two isotopes are forced together. No risk of meltdown or radioactive releases. May also be used to breakdown toxic material. Still in laboratory stages. There is a disagreement over whether to phase out nuclear power or keep this option open in case other alternatives do not pan out.