Chapter 17

Energy

Steamgenerator

Waterpumps

Crane formoving fuel rods

TurbinesTurbines

ReactorReactor

Coolingpond

Coolingpond

5 Reactor power output was lowered too much, making it too difficult to control.

4 Additional water pump to cool reactor was turned on. But with low power output and extra drain on system, water didn’t actually reach reactor.

3 Automatic safety devices that shut down the reactor when water and steam levels fall below normal and turbine stops were shut off because engineers didn’t want systems to “spoil” experiment.

Radiation shieldsRadiation shields

2 Almost all control rods were removed from the core during experiment.

1 Emergency cooling system was turned off to conduct an experiment.

Figure 17-1Page 350

Effects: Blew roof off reactor building Clouds of radioactive material Premature deaths Radioactive crops, cattle Thyroid cancer

Chernobyl

99% of energy comes from the sun

Other 1% comes from commercial energy (nonrenewable)

Commercial energy- burning of fossil fuels 84% nonrenewable 16% renewable

Energy Sources

Figure 17-3aPage 352

World

Nuclear power6%

Hydropower, geothermal,solar, wind

6%

NaturalGas22%

Biomass10%

Oil33%

Coal23%

Figure 17-3bPage 352

United States

Nuclear power8%

Hydropowergeothermalsolar, wind

3%

Biomass3%

NaturalGas24%

Oil39%

Coal23%

Would take at least 50 years (+ huge financial investments) to phase in new energy alternatives

New Energy Alternatives

How much of energy resource is available in near & long-term future?

Net energy yield? Cost for development, phase in, & use? Government research & development

subsidies & tax breaks? How will dependence affect national & global

economic & military security? Vulnerable to terrorism? How will extraction, transportation, & use

affect environment, human health, & climate?

7 Questions Concerning New Energy

Total amount of energy available from resource minus energy needed to find, extract, process, & get resource to consumers

Importance- higher net energy ratios make better energy sources

Oil- high ratio- comes from large, accessible, & cheap-to-extract deposits

Nuclear power- low ratio- requires large amounts of energy input

Net Energy

Petroleum (crude oil)- thick, gooey liquid consisting of combustible hydrocarbons

Extracted- by wells drilled into deposits

Refining- heat & distill (separate by boiling points)

Petroleum

Products of oil distillation

Pesticides Plastics Synthetic fibers Paints Medicines

Petrochemicals

Top 5 reserves- Saudi Arabia, Iraq, United Arab Emirates, Kuwait, Iran

2.9% of oil is found in US reserves 26% of oil is used by US 55% of US oil used is imported

Oil Reserves

Global – 80% depleted within 41-93 years

US – 10-48 years(2005)

Oil Supply

Could increase U.S oil andnatural gas supplies

Could reduce oil importsslightly

Would bring jobs and oilrevenue to Alaska

May lower oil prices slightly

Oil companies havedeveloped Alaskan Oil fields withoutsignificant harm

New drilling techniqueswill leave little environ-mental impact

Figure 17-14Page 360

Trade-OffsDrilling for Oil and Natural Gas

In Alaska’s ArcticNational Wildlife Refuge

Only 19% of finding oil equal to what U.S. consumes in 7-24 months

Too little potential oil to significantlyreduce oil imports

Costs too high and potential oil supply toolittle to lower energy prices

Studies show considerable oil spills andother environmental damage fromAlaskan oil fields

Potential degradation of refuge notworth the risk

Unnecessary if improved slant drillingallows oil to be drilled fromoutside the refuge

Advantages Disadvantages

Ample supply for 42-93 years

Low cost (with huge subsidies)

High net energy yield

Easily transported withinand between countries

Low land use

Technology is welldeveloped

Efficient distribution system

Advantages

Figure 17-15Page 360

Trade-Offs

Conventional Oil

Disadvantages

Need to find substitute within 50 years

Artifically low price encourages waste and discourages search for alternative

Air pollution when burned

Releases CO2 when burned

Moderate water pollution

Advantages Disadvantages

Moderate cost (oil sand)

Large potential supplies, especially oil sandsin Canada

High cost (oil shale)

Low net energy yield

Large amount of water needed for processing

Severe land disruption from surface mining

Water pollution from mining residues

Air pollution when burned

CO2 emissionswhen burned

Easily transported within and between countries

Efficient distributionsystem in place

Figure 17-18Page 362

Trade-OffsHeavy Oils from

Oil Shale and Oil Sand

Technology is well developed

Natural Gas Underground deposits of gases 50-80% methane (by weight)

Remaining is propane or methane

LPG – liquefied petroleum gas – natural gas mixture of liquefied propane & butane gas

LNG – liquefied natural gas – natural gas converted to liquid by cooling to low temperature

Natural Gas Reserves Russia Iran Qatar

3% of reserves found in US

World supply – should last 62-125 years US supply – 55-80 years

Good fuel for fuel cells and gas turbines

Low land use

Easily transported by pipeline

Moderate environmental impact

Lower CO2 emissions thanother fossil fuels

Less air pollution than other fossil fuels

Low cost (with huge subsidies)

High net energy yield

Ample supplies (125 years)

Sometimes burned off andwasted at wells because of lowprice

Shipped across ocean as highlyexplosive LNG

Methane (a greenhouse gas) can leak from pipelines

Releases CO2 when burned

Nonrenewable resource

Difficult to transfer from one countryto another

Requires pipelines

Figure 17-19Page 363Advantages

Trade-OffsConventional Natural Gas

Disadvantages

Coal Solid, combustible mixture of organic

compounds with 30-98% Carbon by weight

Extraction- underground (subsurface) mining, surface mines

2 major uses- steel production & electricity

Increasing moisture content

Increasing heat and carbon content

Peat(not a coal)

Lignite(brown coal)

Bituminous Coal(soft coal)

Anthracite(hard coal)

Heat

Pressure Pressure Pressure

Heat Heat

Partially decayedplant matter in swampsand bogs; low heatcontent

Low heat content;low sulfur content;limited supplies inmost areas

Extensively usedas a fuel becauseof its high heat contentand large supplies;normally has ahigh sulfur content

Highly desirable fuelbecause of its highheat content andlow sulfur content;supplies are limitedin most areas

Figure 17-20Page 364

Coal Reserves US, Russia, China

25% of reserves are in US

World supply- 300 years US- 300-400 yrs

Low cost (with huge subsidies)

High net energy yield

Ample supplies(225–900 years)

Releases radioactive particles and mercury into air

High CO2 emissions when burned

Severe threat to human health

High land use (including mining)

Severe land disturbance, air pollution, and water pollution

Very high environmental impact

Mining and combustiontechnology well-developed

Air pollution can be reduced with improvedtechnology (but addsto cost)

Figure 17-21Page 365Advantages

Trade-Offs

Coal

Disadvantages

Moderate cost (with large government subsidies)

Vehicle fuel

Large potential supply

High water use

Increased surface mining of coal

High environmental impact

Requires mining 50% more coal

Higher cost than coal

Low to moderate net energy yield

Lower air pollution when burned than coal

Figure 17-22Page 365Advantages

Trade-Offs

Synthetic Fuels

Disadvantages

High CO2 emissions when burned

Nuclear Fission Reactor Isotopes of Uranium & Plutonium are split

(chain reaction) Heat generated produces steam which

turns turbine = electricity

Light-water Nuclear System (LWR) Fuel- uranium oxide- stable uranium

pellets Control rods- neutron-absorbing material;

regulates fission/power Moderator- slows neutrons to continue

chain rxn (water, graphite) Coolant- water-circulates through core to

remove heat from fuel rods & to produce steam

Containment vessel- thick, strong walls; keeps radioactive material from escaping to environment

Water-filled pools (dry casks)- on-site storage for highly radioactive (spent) fuel rods

Nuclear Fuel Cycle Mining uranium Processing as fuel Use in reactor Safely storing wastes Disposing of reactor

Open Nuclear Fuel Cycle Isotopes are not removed by reprocessing

nuclear wastes Eventually reburied in underground

disposal facility

Closed Nuclear Fuel Cycle Fissionable isotopes (Uranium-235 &

Plutonium-239) are removed from spent fuel assemblies for reuse as nuclear fuel

Must be stored for 10,000 years

Figure 17-24Page 368

Decommissioning of reactor

Reactor

Fuel assemblies

Enrichment UF6

Conversion of U3 O8 to UF6

Fuel fabrication

(conversion of enrichedUF6 to UO2 and fabricationof fuel assemblies)

Uranium 235 asUF6 Plutonium-239as PuO2

Low level radiationwith long half-life

Spent fuelreprocessing

Temporary storageof spent fuel assemblies

underwater or in dry casks

Geologic disposal of moderateand high-level radioactive wastes

Open fuel cycle today

Prospective “closed” end of fuel cycle

Nuclear Power Dev. After WW2 Atomic Energy Commission- promised

lower cost for nuclear energy (vs. coal) Government (taxpayers) paid ¼ cost of

building commercial reactors & guaranteed there would be no cost overruns

After insurance companies refused to insure nuclear power, Congress passed Price-Anderson Act to protect US nuclear industry & utilities from significant liability in accidents

7 Factor of Declined Use of NP Multibillion dollar construction cost

overruns Higher operating costs More malfunctions than expected Poor management Public safety concerns Stricter government safety regulations Investor concerns about economic

feasibility of nuclear power

Low risk of accidents because of multiple safety systems (except in 35 poorly designed and run reactors in former Soviet Unionand Eastern Europe)

Moderate land use

Moderate land disruption and water pollution(without accidents)

Emits 1/6 as much CO2 as coal

Low environmentalimpact (without accidents)

Large fuel supply

Spreads knowledge andtechnology for building nuclear weapons

No widely acceptable solution for long-term storage of radioactive wastes and decommissioning worn-out plants

Catastrophic accidents can happen (Chernobyl)

High environmental impact (with major accidents)

Low net energy yield

High cost (even with large subsidies)

Figure 17-26Page 370

Subject to terrorist attacks

Advantages

Trade-Offs

Conventional Nuclear Fuel Cycle

Disadvantages

Ample supply

High net energy yield

Very high air pollution

High CO2 emissions

High land disruption fromsurface mining

High land use

Low cost (with huge subsidies)

Ample supply of uranium

Low net energy yield

Low air pollution (mostly from fuel reprocessing)

Low CO2 emissions (mostly from fuel reprocessing)

Much lower land disruption fromsurface mining

Moderate land use

High cost (with hugesubsidies)

Figure 17-27Page 371Coal

Trade-Offs

Coal vs. Nuclear

Nuclear

Safety Features Multiple built-in safety features 15-45% chance of complete core

meltdown in US reactor during the next 20 years

39 US reactors have 80% chance of failure in containment shell from meltdown or explosion

Vulnerable to Terrorist Attack Plants were not designed to withstand an

attack like September 11 Insufficient security against ground-level

attacks

Attack on Stored Radioactive Waste Highly radioactive & thermally hot fuel

would be exposed to air & steam Zirconium outer cover would catch fire Fire would burn for days Release significant amount of radioactive

material into atmosphere Large areas contaminated for decades Economic & psychological havoc

Low-Level Waste Gives off small amounts of ionizing

radiation Must be stored safely for 100-500 years Placed in steel drums & shipped to 2

regional (state or fed run) landfill

Includes: tools, building materials, clothing, glassware, & other contaminated items

High-Level Waste Bury deep underground Shoot into space or sun Bury in Antarctic ice sheet or Greenland

ice cap Dump into subduction zone Bury in mud deposits in ocean basins Change into harmless isotopes

Yucca Mountain Storage Site+Negligible risks of accident or sabotage of waste shipments-Decrease national security-Many shipments of waste material-Geologic instability

Decommissioning of Worn-out Nuclear Power Plants Dismantle plant & store large volume of

highly radioactive materials in high-level nuclear waste storage facility

Physical barrier around plant with full-time security for 30-100 years before dismantling plant

Enclose entire plant in tomb that must last & be monitored for several thousand years

Dirty Radioactive Bombs Explosion & cancers could kill thousands Spread radioactive material over hundreds

of city blocks Contaminate buildings & soil Clean-up would cause billions $$ Intense psychological terror & panic

Conventional Nuclear Power+ Lower operating costs- Must include total cost

Breeder Nuclear Fission+ Generate more nuclear fuel than they consume- Failed safety system could result in loss of liquid sodium coolant = combustion in air & explosion in water- Slow process- Cost

Nuclear Fusion+ No emissions of air pollutants (carbon dioxide)+ Infinite fuel source (water)+ Less radioactive waste+ No risk of meltdown or release of large amounts of radioactive materials+ Little risk of bomb-grade materials+ Used to destroy toxic waste- Negative energy yield- Cost

Government SubsidiesFor the research & development of conventional nuclear power: Conventional nuclear power cannot

compete in today’s open, decentralized, & unregulated energy market

Should keep nuclear options available for future use