Nonrenewable Energy Chapter 15 Energy Resources and Fossil

Nonrenewable Energy Chapter 15

Energy Resources and Fossil Fuels

Fossil Fuels • Most of the energy we use comes from a group of natural resources called fossil fuels. • Fossil fuels –

Fuels for Different Uses • Fuels are used for four main purposes: – Transportation – Manufacturing – Heating and cooling buildings – Generating electricity to run machines and appliances.

Types of Nonrenewable Energy • Coal, oil, natural gas, and uranium (used for nuclear power) are all nonrenewable energy resources.

Commercial Energy Use by Source for the World and the United States

Electricity • The energy in fuels is often converted into electrical energy in order to power machines, because electricity is more convenient to use.

How is electricity generated? • Electric generator – • Most commercial electric generators convert the movement of a turbine into electrical energy – Turbine -

Waste heat Coal bunker Cooling tower transfers waste heat to atmosphere Turbine Generator Cooling loop Stack Pulverizing mill Boiler Condenser Filter Ash disposal Fig. 15 -15 a, p. 387

Energy Use • Everything from the food you eat to the clothes you wear requires energy to produce.

Energy Use • People in developed societies use much more energy than people in developing countries do.

Energy Use in the US • The United States uses more energy person than any other country in the world except Canada and the United Arab Emirates.

Fossil Fuels • Nonrenewable energy

Advantages and Disadvantages of Oil • Oil that is pumped from the ground is also known as crude oil, or Petroleum • Petroleum product –

Locating Oil Deposits • Oil is found in and around major geologic features that tend to trap oil as it moves in the Earth’s crust. • Exploration wells are drilled to determine the volume and availability of the oil deposit

Oil Formation • Oceanic microscopic plants/animals die, sink to bottom, form layers of sediment • Buried deeper, increased heat/pressure • Amount of heat determines oil or natural gas

Predicting Oil Production • Oil reserves – • Oil deposits

The Environmental Effects of Using Oil • When petroleum fuels are burned, they release pollutants. • These pollutants contribute to the formation of smog and cause health problems. • Carbon dioxide emissions contribute to climate change • Oil spills harm ecosystems

OPEC • OPEC – Organization of Petroleum Exporting Countries – 13 countries – >60% world’s crude oil reserves – Produce 45% of the world’s oil

Case Study: ANWR • Arctic National Wildlife Refuge (Alaska) • • http: //www. nationalgeographic. com/adventure/media/anwr-wild-chronicles. wmv http: //www. fws. gov/alaska/nwr/arctic/issues 1. htm

Oil Sands and Oil Shales • Oil sand – – Canada has 75% – Releases a lot of CO 2 – Produces a lot of toxic sludge

Oil Sands and Oil Shales • Oil shales contain kerogen – After distillation: shale oil • 72% of the world’s reserve is in arid areas of western United States

Natural Gas • Natural gas contains 50 -90% methane (CH 4) • Supplies about 21 percent of the world’s nonrenewable energy • Burning natural gas produces fewer pollutants than other fossil fuels • Considered “cleaner”

Trade-Offs: Conventional Natural Gas

Coal § Coal: solid fossil fuel § Burned in 2100 power plants, generates 40% of the world’s electricity • Inefficient

Coal Formation

Coal • Most of the world’s fossil-fuel reserves are made up of coal. • Asia and North America are particularly rich in coal deposits. • Two major advantages of coal:

Coal

Coal • • Some coal burns cleaner than other coal High grade coal – Low grade coal – Burning low grade coal that has a lot of sulfur can lead to acid rain.

Waste heat Coal bunker Cooling tower transfers waste heat to atmosphere Turbine Generator Cooling loop Stack Pulverizing mill Boiler Condenser Filter Ash disposal Fig. 15 -15 a, p. 387

Coal Mining and the Environment • Environmental costs of burning coal – Severe air pollution – Is there really a “clean coal”? – http: //www. cbsnews. com/news/the-dilemma-over-coal-generated-power/

Fossil Fuels and the Future • Today, fossil fuels supply about 90 percent of the energy used in developed countries. • As the demand for energy resources increases, the cost of fossil fuels will likely increase enough to make other energy sources more attractive.

Coal, Oil, and Natural Gas Deposits

Hydraulic Fracturing • AKA Hydrofracking or Fracking • Method of extracting underground natural gas • Very controversial due to concerns over groundwater pollution

Energy Production by Source

Nuclear Energy

Case Study: Three Mile Island, PA

Case Study: Worst Commercial Nuclear Power Plant Accident in the U. S. • Three Mile Island – March 29, 1979 – Near Harrisburg, PA, U. S. – Nuclear reactor lost its coolant – Led to a partial uncovering and melting of the radioactive core – Unknown amounts of radioactivity escaped – People fled the area – Increased public concerns for safety • Led to improved safety regulations in the U. S.

Case Study: Three Mile Island, PA • The Three Mile Island Unit 2 (TMI-2) reactor, near Middletown, Pa. , partially melted down on March 28, 1979. This was the most serious accident in U. S. commercial nuclear power plant operating history, although its small radioactive releases had no detectable health effects on plant workers or the public. Its aftermath brought about sweeping changes involving emergency response planning, reactor operator training, human factors engineering, radiation protection, and many other areas of nuclear power plant operations. It also caused the NRC to tighten and heighten its regulatory oversight. All of these changes significantly enhanced U. S. reactor safety.

Fission: Splitting Atoms • Nuclear energy • Nuclear power plants get their power from nuclear energy • Nuclear fission –

How Nuclear Energy Works • Fueled by uranium ore and packed as pellets in fuel rods and fuel assemblies • Water is the usual coolant • Containment shell around the core for protection • Water-filled pools or dry casks for storage of radioactive spent fuel rod assemblies

Small amounts of radioactive gases Uranium fuel input (reactor core) How Nuclear Energy Works Control rods Containment shell Heat exchanger Waste heat Steam Turbine Generator Hot coolant Hot water output Coolant Cool water input Moderator Shielding Pressure Coolant vessel passage Periodic removal and storage of radioactive wastes and spent fuel assemblies Periodic removal and storage of radioactive liquid wastes Water Useful electrical energy about 25% Waste heat Condenser Water source (river, lake, ocean) Fig. 15 -22 a, p. 390

Decommissioning of reactor Fuel assemblies Enrichment of UF 6 Reactor Fuel fabrication (conversion of enriched UF 6 to UO 2 and fabrication of fuel assemblies) Conversion of U 3 O 8 to UF 6 Uranium-235 as UF 6 Plutonium-239 as Pu. O 2 Temporary storage of spent fuel assemblies underwater or in dry casks Spent fuel reprocessing Low-level radiation with long half-life Mining uranium ore (U 3 O 8) Open fuel cycle today Recycling of nuclear fuel Geologic disposal of moderate and high-level radioactive wastes Fig. 15 -23, p. 392

Advantages of Nuclear Energy • Nuclear energy does not produce air polluting gases • Capable of generating a lot of energy • When operated properly, less radioactivity than coal fired power plants

Disadvantages of Nuclear Energy • • Storage of waste Safety concerns Low net yield of energy of the nuclear fuel cycle Slowest growing energy source

Nuclear Waste Storage Concerns • The difficulty of finding a safe place to store nuclear wastes is one of the greatest disadvantages of nuclear power. • Storage sites for nuclear wastes must be located in areas that are geologically stable for tens of thousands of years.

Case Study: Worst Nuclear Power Plant Accident in the World • Chernobyl – April 26, 1986 – In Chernobyl, Ukraine – Series of explosions caused the roof of a reactor building to blow off – Partial meltdown and fire for 10 days – Huge radioactive cloud spread over many countries and eventually the world – 350, 000 people left their homes – Effects on human health, water supply, and agriculture

Remains of a Nuclear Reactor at the Chernobyl Nuclear Power Plant