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 – are the remains of ancient organisms that changed into coal, oil, or natural gas.

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 – a machine that converts mechanical energy, or motion, into electrical energy. Most commercial electric generators convert the movement of a turbine into electrical energy Turbine - a wheel that changes the force of a moving gas or a liquid into energy that can do work.

Cooling tower transfers waste heat to atmosphere Coal bunker Turbine Generator Cooling loop Stack Pulverizing mill Condenser Filter Boiler Ash disposal Fig. 15-15a, 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 per person than any other country in the world except Canada and the United Arab Emirates.

Fossil Fuels Nonrenewable energy Coal Oil Natural gas

Advantages and Disadvantages of Oil Oil that is pumped from the ground is also known as crude oil, or Petroleum Petroleum product – anything that is made from crude oil, such as fuels, chemicals, and plastics

Lowest Boiling Point Gases Gasoline Aviation fuel Heating oil Diesel oil Naphtha Grease and wax Heated crude oil Asphalt Furnace Highest Boiling Point Fig. 15-4a, p. 377

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 If enough oil for profit, will drill Seismic Imaging

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 High heat – lighter oil Even higher heat – natural gas Will migrate through pores until it gathers under impermeable layer

https://www.youtube.com/watch?v=8YHsxXEVB1M

Predicting Oil Production Oil reserves - are oil deposits that can be extracted profitably at current prices using current technology. Oil deposits are yet to be discovered or to become commercial.

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/issues1.htm

Oil Sands and Oil Shales Oil sand – a mixture of clay, sand, water, and bitumen (organic material) Canada has 75% Releases a lot of CO2 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 Locked up in rock Water needed for extraction and processing Low net energy yield

Natural Gas Natural gas contains 50-90% methane (CH4) Supplies about 21 percent of the world’s nonrenewable energy Burning natural gas produces fewer pollutants than other fossil fuels Considered “cleaner”

Conventional Natural Gas Trade-Offs Conventional Natural Gas Advantages Disadvantages Ample supplies Low net energy yield for LNG Versatile fuel Production and delivery may emit more CO2 and CH4 per unit of energy produced than coal Medium net energy yield Fracking uses and pollutes large volumes of water Emits less CO2 and other air pollutants than other fossil fuels when burned Potential groundwater pollution from fracking Fig. 15-11, p. 383

Coal Coal: solid fossil fuel Burned in 2100 power plants, generates 40% of the world’s electricity Inefficient Three largest coal-burning countries China United States Canada

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 it is relatively inexpensive it needs little refining after it has been mined.

Coal

Bituminous (soft coal) Anthracite (hard coal) Increasing heat and carbon content Increasing moisture content Peat (not a coal) Lignite (brown coal) Bituminous (soft coal) Anthracite (hard coal) High grade coal – less pollution Low grade coal – more pollution Burning low grade coal that has a lot of sulfur can lead to acid rain. Heat Heat Heat Pressure Pressure Pressure Partially decayed plant matter in swamps and bogs; low heat content Low heat content; low sulfur content; limited supplies in most areas Extensively used as a fuel because of its high heat content and large supplies; normally has a high sulfur content Highly desirable fuel because of its high heat content and low sulfur content; supplies are limited in most areas

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

Coal Mining and the Environment Environmental costs of burning coal Severe air pollution Sulfur released as SO2 Large amount of soot CO2 Trace amounts of Hg and radioactive materials 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.

Self Quiz What are fossil fuels? How do fossil fuels form? What are some environmental problems associated with different fossil fuels? When might renewable energy become more common than fossil fuels?

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 Wastewater associated with shale gas extraction can contain high levels of dissolved solids, fracturing fluid additives, metals, and naturally occurring radioactive materials.

https://www.youtube.com/watch?v=Uti2niW2BRA http://www.youtube.com/watch?v=lB3FOJjpy7s

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.

Case Study: Three Mile Island http://abcnews.go.com/Archives/video/march-30-1979-three-mile-island-nuclear-reactor-radiation-9625032

Fission: Splitting Atoms Nuclear energy- the energy within the nucleus of an atom Nuclear power plants get their power from nuclear energy Nuclear fission – splitting the nuclei of atoms Fission releases a tremendous amount of energy

http://www.scienceclarified.com/Mu-Oi/Nuclear-Fusion.html

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

How Nuclear Energy Works Small amounts of radioactive gases How Nuclear Energy Works Uranium fuel input (reactor core) Control rods Containment shell Waste heat Heat exchanger Steam Turbine Generator Hot coolant Useful electrical energy about 25% Hot water output Pump Pump Coolant Pump Pump Waste heat Cool water input Moderator Shielding Pressure vessel Coolant passage 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. 15-22a, p. 390

(conversion of enriched UF6 to UO2 and fabrication of fuel assemblies) Decommissioning of reactor Fuel assemblies Reactor 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 Geologic disposal of moderate and high-level radioactive wastes Mining uranium ore (U3O8) Open fuel cycle today Recycling of nuclear fuel Fig. 15-23, p. 392

https://www.youtube.com/watch?v=rcOFV4y5z8c

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

Fukushima

Fukushima

Half Life Practice The half-life of strontium-90 is 25 years. How much strontium-90 will remain after 100 years if the initial amount is 4.0 g? Potassium-42 has a half-life of 12.4 hours. How much of an 848 g sample of potassium-42 will be left after 62.0 hours?