CHAPTER 17 Non-renewable Energy

Laws of Thermodynamics 1st Law: Energy is neither created nor destroyed, but converted from one form to another 2nd Law: When energy changes forms, it becomes less usable (usually released as heat)

Net energy yield: The amount of energy gained minus the amount of energy used to obtain the energy.

Turbines!! Any volunteers?

Nonrenewable Energy Resources Oil resources Natural gas resources Methane Hydrate Coal resources Synthetic fuels made from coal Nuclear fission

Evaluating Energy Resources Renewable energy Non-renewable energy Future availability Net energy yield Costs Environmental effects Fig. 17-3 p. 352

North American Energy Resources Fig. 17-9 p. 357

Oil – What is it? Petroleum (crude oil) Thick, gooey liquid Fig. 17-8 p. 356 Petroleum (crude oil) Thick, gooey liquid consisting of hundreds of combustible hydrocarbons Made from buried, dead, organic material

Oil – Where is it found? Deep underground Oil shale: fine-grained sedimentary rocks containing a combustible mixture of hydrocarbons called Kerogen Tar sand: mixture of clay, sand, water and a combustible organic material called bitumen

Oil – How does it work? The oil is refined and separated Fig. 17-8 p. 356 The oil is refined and separated It is used by burning it – by breaking the carbon bonds Heat from burning it produces heat and spins a turbine

Conventional Oil: Advantages Relatively low cost (subsidized) High net energy yield Efficient distribution system Refer to Fig. 17-15 p. 360

Conventional Oil: Disadvantages Running out Low prices encourage waste Air pollution and Greenhouse gases Water pollution Refer to Fig. 17-15 p. 360

Oil - Wastes? Other than air and water pollution, it releases CO2 into the atmosphere.

Natural Gas Mostly Methane Some Ethane Propane Butane Hydrogen sulfide (highly toxic)

Natural Gas… Is found above crude oil Can be burned to heat water and buildings and to generate electricity

Natural Gas Advantages Ample supply: 120 years+ High net energy yield Less air pollution than oil Good fuel for fuel cells and gas turbines

Natural Gas - disadvantages Nonrenewable Methane can leak Difficult to transfer between countries Sometimes it is burned off/wasted Required pipelines

Natural Gas – wastes? CO2 Methane (through leaks)

Methane Hydrate Methane hydrate is methane trapped in water molecules It is found under arctic permafrost and beneath the seafloor It is known as “fire ice” Same uses as natural gas

Methane Hydrate –pros & cons Very abundant Cons: Adds a large amount of greenhouses gases into the atmosphere Hard to get to CO2 is the major by-product

Coal – What is it? Coal is a solid fossil fuel formed in several stages buried remains of plants are subject to heat and pressure Contains carbon & sulfur

Coal Formation and Types Fig. 17-20 p. 364

Coal Coal is strip-mined in different areas Burned to generate 62% of the world’s electricity

Coal Power Plant

Very high environmental impact Trade-Offs Coal Advantages Disadvantages Ample supplies (225–900 years) Very high environmental impact Severe land disturbance, air pollution, and water pollution High net energy yield Low cost (with huge subsidies) High land use (including mining) Mining and combustion technology well-developed Severe threat to human health High CO2 emissions when burned Air pollution can be reduced with improved technology (but adds to cost) Releases radioactive particles and mercury into air

Coal – wastes? CO2 emissions Releases radioactive particles

Synthetic Fuels Synthetic fuels are coal converted into gaseous or liquid form It is made through a process called “coal liquification” Burned to generate heat

Large potential supply Low to moderate net energy yield Trade-Offs Synthetic Fuels Advantages Disadvantages Large potential supply Low to moderate net energy yield Higher cost than coal Vehicle fuel Requires mining 50% more coal High environmental impact Moderate cost (with large government subsidies) Increased surface mining of coal High water use Lower air pollution when burned than coal High CO2 emissions when burned

Synthetic fuel - wastes? Higher CO2 emissions than coal

Nuclear Energy Let’s all say it together: Nu (new) Cle (clee) Ar (er)

Nuclear Fission Isotopes of uranium and plutonium undergo controlled nuclear fission This breaks apart molecules, releasing heat Uranium is mined

The Nuclear Fuel Cycle Fig. 17-24 p. 368 Small amounts of radioactive gases Uranium fuel input (reactor core) Containment shell Waste heat Electrical power Emergency core cooling system Steam Control rods Useful energy 25 to 30% Turbine Generator Heat exchanger Hot coolant Hot water output Condenser Pump Pump Coolant Coolant passage Moderator Cool water input Pump Waste heat Pressure vessel Water Shielding Waste heat Water source (river, lake, ocean) Periodic removal and storage of radioactive wastes and spent fuel assemblies Periodic removal and storage of radioactive liquid wastes Fig. 17-24 p. 368

Locations of U.S. Nuclear Power Plants Red is operational Blue is decommissioned Green is Yucca Mountain

Trade-Offs Advantages Disadvantages Large fuel supply Conventional Nuclear Fuel Cycle Advantages Disadvantages Large fuel supply High cost (even with large subsidies) Low environmental impact (without accidents) Low net energy yield High environmental impact (with major accidents) Emits 1/6 as much CO2 as coal Moderate land disruption and water pollution (without accidents) Catastrophic accidents can happen (Chernobyl) No widely acceptable solution for long-term storage of radioactive wastes and decommissioning worn-out plants Moderate land use Low risk of accidents because of multiple safety systems (except in 35 poorly designed and run reactors in former Soviet Union and Eastern Europe) Subject to terrorist attacks Spreads knowledge and technology for building nuclear weapons

Nuclear Waste HIGHLY radioactive Lasts for thousands of years Power plants are radioactive after its useful life

Dealing with Nuclear Waste High- and low-level wastes Terrorist threats Underground burial Disposal in space Burial in ice sheets Dumping into subduction zones Burial in ocean mud Conversion into harmless materials

Yucca Mountain Controversy Wastes stored and guarded in one place Possible long-term groundwater contamination Security and safety concerns during waste transport to the site Refer to Fig. 17-29 p. 374

Permanent Underground Disposal of Nuclear Wastes Storage Containers Fuel rod Primary canister Ground Level Overpack container sealed Unloaded from train Personnel elevator Air shaft Nuclear waste shaft Underground Buried and capped Lowered down shaft Fig. 17-28 p. 373

Serious Nuclear Accidents Three Mile Island (1979) Chernobyl (1986): p. 350 Fukushima (2011)