Tidal PowerEnergy conversion kinetic to electricalBenefits pollution-free, cheap, renewableCosts only two places in the U.S. have tides needed to do this

Wave PowerEnergy conversion kinetic to electricalBenefits pollution-free, cheap, renewableCosts - only suitable in areas facing the open ocean (especially on the West Coasts of continents); tend to be destroyed in storms

PRODUCING ELECTRICITY FROM THE WATER CYCLEOcean tides and waves and temperature differences between surface and bottom waters in tropical waters are not expected to provide much of the worlds electrical needs.Only two large tidal energy dams are currently operating: one in La Rance, France and Nova Scotias bay of Fundy where the tidal amplitude can be as high as 16 meters (63 feet).

NUCLEAR ENERGYWhen 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.

Fig. 16-16, p. 372Small amounts of radioactive gasesUranium fuel input (reactor core)Control rodsContainment shellHeat exchangerSteamTurbineGeneratorWaste heatElectric powerHot coolantUseful energy 25%30%Hot water outputPumpPumpCoolantPumpPumpModeratorCool water inputWaste heatShieldingPressure vesselCoolant passageWaterCondenserPeriodic removal and storage of radioactive wastes and spent fuel assembliesPeriodic removal and storage of radioactive liquid wastesWater source (river, lake, ocean)

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

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 AccidentThe worlds 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 ENERGYA 1,000 megawatt nuclear plant is refueled once a year, whereas a coal plant requires 80 rail cars a day.Figure 16-20

Fig. 16-20, p. 376Coal vs. Nuclear Trade-OffsCoal Nuclear Ample supplyAmple supply of uraniumHigh net energy yieldLow net energy yieldVery high air pollutionLow air pollution (mostly from fuel reprocessing)High CO2 emissionsLow CO2 emissions (mostly from fuel reprocessing)High land disruption from surface miningMuch lower land disruption from surface miningLow cost (with huge subsidies)High cost (even with huge subsidies)High land useModerate land use

NUCLEAR ENERGYTerrorists 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 ENERGYWhen 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 ENERGYBuilding 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 ENERGYScientists 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.

NuclearDescription using fission to split large uranium atoms into smaller products and releasing tremendous amounts of heat energy which is used to make steam that turns turbines to create electricityEnergy conversion nuclear to electrical and heatBenefits pollution-free, very, very efficientCosts risk of accidents (spread of radioactivity); transportation and disposal of radioactive wastes (Nimby!) It also produces a ton of thermal pollution!

WAYS TO IMPROVE ENERGY EFFICIENCYWe can save energy in building by getting heat from the sun, superinsulating them, and using plant covered green roofs.We can save energy in existing buildings by insulating them, plugging leaks, and using energy-efficient heating and cooling systems, appliances, and lighting.

Strawbale HouseStrawbale is a superinsulator that is made from bales of low-cost straw covered with plaster or adobe. Depending on the thickness of the bales, its strength exceeds standard construction.Figure 17-9

Living RoofsRoofs covered with plants have been used for decades in Europe and Iceland.These roofs are built from a blend of light-weight compost, mulch and sponge-like materials that hold water.Figure 17-10

Saving Energy in Existing BuildingsAbout one-third of the heated air in typical U.S. homes and buildings escapes through closed windows and holes and cracks.Figure 17-11

Approximate Energy Efficiencies:Photosynthesis: 1%Incandescent light bulbs: 95%

DefinitionAny fuel that meets certain emissions standards; i.e. they give off a certain amount of pollution (or less)Alternative Fuels

Laws InvolvedClean Air Act amendments of 1990Energy Policy Act (EPACT) in Texas of 1992Such laws have led to more research and development of these fuels

Examples of Alternative FuelsBiodiesel made of vegetable oils and alcohols; expensiveDiesel cleaner than normal gasoline, being more refined Biogas by-product of decaying vegetation; need technologyHydrogen expensive and we need more technology

Ethanol/Methanol alcohols; not as efficient (Miles per gallon) and we dont have all the technology ; also, if our grain supplies are used to make fuel, will we have enough to feed the world?Natural Gas expensive and we need more technologyReformulated Gasoline (RFG) regular gas that has been further refined to remove some of the more toxic pollutants

Propane most usable form of alternative fuel; not as efficient (mpg)

Syngas manmade gas made of hydrogen and carbon monoxide; need more technology to use it

HYDROGENSome energy experts view hydrogen gas as the best fuel to replace oil during the last half of the century, but there are several hurdles to overcome:Hydrogen is chemically locked up in water an organic compounds.It takes energy and money to produce it (net energy is low).Fuel cells are expensive.Hydrogen may be produced by using fossil fuels.

Energy LawsPublic Utility Holding Company Act (PUHCA) 1935; regulated the interstate flow of energy; 1st law of its kind; a law designed to protect consumers from corporate abuse of electricity markets(so electric companies cant price gouge.) This was happening during the great depression.

Corporate Average Fuel Economy Act (CAF) 1975; focused attention on efficiency of cars; mpg stickers requiredPublic Utility Regulatory Policies Act (PURPA)1978; higher utility rates for increased electricity use

Converting Plants and Plant Wastes to Liquid Biofuels: An OverviewMotor vehicles can run on ethanol, biodiesel, and methanol produced from plants and plant wastes.The major advantages of biofuels are:Crops used for production can be grown almost anywhere.There is no net increase in CO2 emissions.Widely available and easy to store and transport.

Case Study: Producing EthanolCrops such as sugarcane, corn, and switchgrass and agricultural, forestry and municipal wastes can be converted to ethanol.Switchgrass can remove CO2 from the troposphere and store it in the soil.Figure 17-26

Case Study: Producing Ethanol10-23% pure ethanol makes gasohol which can be run in conventional motors.85% ethanol (E85) must be burned in flex-fuel cars.Processing all corn grown in the U.S. into ethanol would cover only about 55 days of current driving.Biodiesel is made by combining alcohol with vegetable oil made from a variety of different plants..

Case Study: Biodiesel and MethanolGrowing crops for biodiesel could potentially promote deforestation.Methanol is made mostly from natural gas but can also be produced at a higher cost from CO2 from the atmosphere which could help slow global warming.Can also be converted to other hydrocarbons to produce chemicals that are now made from petroleum and natural gas.

WAYS TO IMPROVE ENERGY EFFICIENCYAverage fuel economy of new vehicles sold in the U.S. between 1975-2006.The government Corporate Average Fuel Economy (CAFE) has not increased after 1985.Figure 17-5

Fig. 17-5, p. 388CarsBothAverage fuel economy (miles per gallon, or mpg)Model yearPickups, vans, and sport utility vehicles

WAYS TO IMPROVE ENERGY EFFICIENCYGeneral features of a car powered by a hybrid-electric engine.Gas sipping cars account for less than 1% of all new car sales in the U.S.Figure 17-7

Fig. 17-7, p. 389Regulator: Controls flow of power between electric motor and battery bank.Fuel tank: Liquid fuel such as gasoline, diesel, or ethanol runs small combustion engine.Transmission: Efficient 5-speed automatic transmission.Battery: High-density battery powers electric motor for increased power.Combustion engine: Small, efficient internal combustion engine powers vehicle with low emmissions; shuts off at low speeds and stops.

Electric motor: Traction drive provides additional power for passing and acceleration; excess energy recovered during braking is used to help power motor.FuelElectricity

Hybrid Vehicles, Sustainable Wind Power, and Oil importsHybrid gasoline-electric engines with an extra plug-in battery could be powered mostly by electricity produced by wind and get twice the mileage of current hybrid cars.Currently plug-in batteries would by generated by coal and nuclear power plants.According to U.S. Department of Energy, a network of wind farms in just four states could meet all U.S. electricity means.

Fuel-Cell VehiclesFuel-efficient vehicles powered by a fuel cell that runs on hydrogen gas are being developed.Combines hydrogen gas (H2) and oxygen gas (O2) fuel to produce electricity and water vapor (2H2+O2 2H2O).Emits no air pollution or CO2 if the hydrogen is produced from renewable-energy sources.

Fig. 17-8, p. 390Body attachments Mechanical locks that secure the body to the chassisAir system managementUniversal docking connection Connects the chassis with the drive-by-wire system in the bodyFuel-cell stack Converts hydrogen fuel into electricityRear crush zone Absorbs crash energyDrive-by-wire system controlsCabin heating unitSide-mounted radiators Release heat generated by the fuel cell, vehicle electronics, and wheel motorsHydrogen fuel tanksFront crush zone Absorbs crash energyElectric wheel motors Provide four-wheel drive; have built-in brakes

National Appliance Energy Act 1987; energy efficiency stickers on all appliances

Renewable Energy and Technology Competitiveness Act 1989; effort to develop renewable energy nationallyClean Air Act Amendments 1990; set standards for cities and emissionsEnergy Policy Act 1992; comprehensive effort to find renewable energy resources

Hydrogen Future Act 1996; develop hydrogen as an energy source

PROBLEM FEW of these actually provide the money needed to research renewable resources

***Figure 16.16Science: light-watermoderated 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?******Figure 16.20Trade-offs: comparison of the risks of using nuclear power and coal-burning plants to produce electricity. A 1,000-megawatt nuclear plant is refueled once a year, whereas a coal plant of the same size requires 80 rail cars of coal a day. QUESTION: If you had to, would you rather live next door to a coal-fired power plant or a nuclear power plant? Explain.***************Figure 17.5Natural capital depletion and degradation: average fuel economy of new vehicles sold in the United States, 19752006. After increasing between 1973 and 1985, average fuel efficiency for new vehicles leveled off and in recent years has declined. (U.S. Environmental Protection Agency and National Highway Traffic Safety Administration)**Figure 17.7Solutions: general features of a car powered by a hybrid gasolineelectric engine. (Concept information from DaimlerChrysler, Ford, Honda, and Toyota)***Figure 17.8Solutions: prototype hydrogen fuel-cell car developed by General Motors. This ultralight and ultrastrong car consists of a skateboard-like chassis and a variety of snap-on fiberglass bodies. It handles like a high-speed sports car, zips along with no engine noise, and emits only wisps of warm water vapor and heatno smelly exhaust, no smog, no greenhouse gases. General Motors claims the car could be on the road within a decade, but some analysts believe that it will be 2020 before this and fuel-cell cars from other manufacturers will be mass produced. (Basic information from General Motors)