Chapter 13 - Energy

1. Chapter 13 - Energy By Ari Brady, Laura Slote, Sydney Bell, and Bronwyn Austin APES 6th Period

2. Case Study • The Rocky Mountain Institute • - 99% of space and water heating from sun • - 95% of daytime lighting from sun • - uses one tenth the usual amount of electricity • New green and smart buildings being developed • - Superinsulating windows • -sensor controlled • - electricity from solar cells

3. 13-1 Evaluating Energy Resources • About 99% of the energy heating earth and our buildings comes from the sun • - indirectly e.g. wind, hydropower, biomass • Remaining 1% of energy from burning fossil fuels • - commercial energy • - mostly nonrenewable • - important nonrenewable energy resources: coal, oil, natural gas, some geothermal energy

4. 13-1 • About half the people in the world (mostly in developing countries) burn wood and charcoal for heat and cooking • - only renewable if wood supplies harvested renewably • - many face fuelwood shortages • United States in world's largest energy user • - average American consumes in one day the energy a person in the poorest countries consumes in a year • - in 2005, we used almost 1/4 of the world's commercial energy • - 93% of the energy we use is nonrenewable • - what will we use in the future?

5. 13-1 • We need new energy policies • - gov't needs to give new clean energy resources subsidies and tax breaks • - normally takes at least 50 years and a huge amount of money before new energy alternative provide 10-20% of total energy use • - must ask questions (how available, net energy yield, etc.) • To get energy, it takes energy • - net energy = (total energy available over the resources lifetime) - (energy used + automatically wasted + unnecessarily wasted) • - expressed as a ratio of useful energy/energy used to produce

6. 13-2 Nonrenewable Fossil Fuels • Crude oil - contains hydrocarbons, which we take from underground deposits • - divided into gas, heating oil, asphalt, etc. • - well drilled to extract oil, moderate damage to land • - taken to refinery, heated, distilled, separated • Eleven countries have 78% of the world's proven oil reserves (mostly in Middle East) • - Oil industry is the world's largest business • - Organization of Petroleum Exporting Countries (OPEC) • - Saudi Arabia has 25%, Canada follows with 15%

7. 13-2 • The US is the largest oil user (26%,) but only has 2.9% of the world's unproven oil reserves • - imports most of oil, increasingly dependant on Middle East • We aren't running out of oil... yet • - Globally, projected to last for 42- 93 years • - US supply for 10- 48 years • - Supply will then be 80% depleted

8. 13-2 • Conventional oil: pros and cons • Pros: • - low cost, big subsidies, high net energy yield, easily transported, low land use, developed technology, efficient distribution system • Cons: • - will run out, artificially low price, air pollution, releases carbon dioxide, moderate water pollution • Possible alternatives • - heavy oils from oil sand and oil shale • - but bad for land, other negative effects

9. 13-2 • Natural gas • - mostly consists of methane, bit of hydrocarbons • - conventional natural gas mostly found above reservoirs of crude oil • - often wasted • - unconventional natural gas found by itself • - currently costs too much to collect, but technology is being developed

10. 13.2 • Coal • abundant energy resources burned mostly to produce electricity and steel • solid fossil fuel (world's most abundant) • harmful to environment • formed in several stages as plants were subjected to intense heat and pressure 300-400 million years ago

11. 13.2 • Coal usage... • Advantages • most abundant fossil fuel • high net energy yield • low cost • well-developed mining and combustion technology • Disadvantages • not as versatile as oil and natural gas • high environmental impact • releases the most carbon dioxide into the atmosphere • harmful health effects

12. 13.2 • Converting Solid Coal into Gaseous and Liquid Fuels... • Synthetic natural gas (SNG) is created through coal gasification • liquid fuel is created through coal liquefaction • Advantages • burn cleaner than coal • vehicle fuel • large potential supply • Disadvantages • high costs • producing and burning them add more carbon dioxide into the atmosphere than burning solid coal • low to moderate net energy yeild

13. 13.3 Nonrenewable Nuclear Enery • How nuclear fission reactors work: • Isotopes of uranium and plutonium undergo nuclear fission inside a nuclear reactor. Then the resulting heat, produces steam that spins turbines to generate electricity. • Within a light-water reactor (LWR): • control rods • coolant • containment vessel • water-filled pools or dry casks

15. 13.3 • The Chernobyl Nuclear Power Plant Accident • a series of explosions in one of the reactors blew the roof off a reactor building and radioactive debris entered the atmosphere • world's worst nuclear power plant accident • Ukraine, 1986 • disaster caused by poor reactor design and human error • thousands of premature deaths as a result

16. 13.3 • The Nuclear Power Fuel Cycle • Advantages • large fuel supply • low environmental impact • emits 1/6 as much carbon dioxide as coal • moderate land disruption and pollution • low risk of accidents • Disadvantages • high cost • low net energy yield • high environmental impact • catastrophic accidents • no widely acceptable solution for storage of radioactive wastes • subject to terrorist attacks • spreads knowledge for building nuclear weapons

17. 13.3 • High-Level Radioactive Waste • must be stored for at least • 10,000 years or 240,000 years • if plutonium-239 is not removed • by reprocessing as part of the • nuclear fuel cycle • Methods of Storage • bury it deep underground • shoot it into space or into the sun • bury it under the antarctic ice sheet or Greenland's ice cap • dump it into descending zones of the earth's crust • bury it in thick deposits of mud on the deep-ocean floor • change it into harmless or less harmful isotopes

18. 13.3 • Radioactive Waste in the United States • being built now: a repository for underground storage of high-level radioactive wastes from commercial nuclear reactors on federal land in the Yucca Mountain desert region, 160 kilometers northwest of Las Vegas, Nevada • Dealing with Worn-Out Nuclear Plants • must be decommissioned or retired • dismantle the plant and store in nuclear waste facility • install a physical barrier around the plant and set up full-time security • enclose entire plant in a tomb that must last and be monitored for several thousand years

19. 13.3 • "Dirty Bombs" • terrorists could wrap conventional explosives around small amounts of various radioactive materials, detonate them, and contaminate large areas with radioactivity • Can Nuclear Power Reduce Dependence on Imported Oil and Help Reduce Global Warming? • no, the nuclear fuel cycle produces some carbon dioxide as well and so little oil is burned to produce electricity that it won't reduce dependence on imported oil

20. 13.3 • Economics of Nuclear Power • government subsidies partially shield nuclear power from free-market competition with other energy sources • however, nuclear power fuel cycle is still very expensive • new idea to build smaller, second-generation plants using standardized designs called advanced light-water reactors • Breeder Nuclear Fission • generate more nuclear fuel than they consume by converting nonfissionable uranium-238 into fissionable plutonium-239 • however, it's very expensive and isn't very safe

21. 13.3 • Nuclear Fusion • nuclear fusion is a nuclear change in which two isotopes of light elements are forced together at extremely high temperatures until they fuse to form a heavier nucleus, releasing energy • many advantages including no risk of a meltdown, yet it remains at the laboratory stage • the problem: all tests so far have not been able to produce more energy than it uses

22. 13-4 Improving Energy Efficiency • Co-generation: (combined heat and power systems) two useful forms of energy, such as steam and electricity, are produced from the same fuel source • Up to 80% efficiency compared to 30% for coal fire boilers and nuclear power plants • Replace energy-wasting electric motors (consume ¼ of the energy in the United States), these motors only run at full speed

23. 13-4 • Saving Energy In Transportation • The best way to increase energy savings is to increase the fuel efficiency of motor vehicles, yet fuel efficient cars account for less than 1% of all car sales • Inflation adjusted price of gas in the US is low • 2/3 of US consumers prefer the SUVs, pickup trucks and minivans as opposed to fuel efficient cars • Government failure to establish efficiency standards

24. 13-4 • Hybrid and Fuel-Cell Cars • Hybrid-electric internal combustion engine: runs on gas, diesel fuel, or natural gas in addition to using a small battery • Sales are projected to grow rapidly and dominate sales • Fuel cell cars: contain a device that combines hydrogen gas and oxygen gas in the air to produce electrical energy to power the car and water vapor • At least twice efficient as standard engines • Require little maintenance and produce minimal pollution

25. 13-4 • Designing Buildings to Save Energy • Getting heat from the sun • Super-insulation • Plant-covered eco-roofs • Strawbale housing

26. 13-4 • Super Insulated Housing • Cost 5% more to build, yet this cost is paid back within 5 years • Saves around 50,000 over a 40 year period • Uses 90% less energy than typical heating

27. 13-4 • Green Roofs • Covered with plants (common in Germany and other parts of Europe) • Provide good insulation, absorb storm water and slowly release it, outlast normal roofs

28. 13-4 • Saving Energy In Existing Buildings • Insulate and Plug Leaks- 1/3 of heated air escapes through windows and cracks • Energy Efficient Windows-cut heat losses by 2/3, lessen cooling costs • Heat Houses More Efficiently- super-insulation, geothermal heat pumps, passive solar heating • Heat Water More Efficiently- tankless instant water heaters heat water instantly as is flows through a burner • Energy Efficient Appliances- efficient refrigerators, ovens, dryers, etc.

29. 13-5 • Renewable Energy For Heat and Electricity • Solar • Flowing water • Wind • Biomass • Hydrogen • Geothermal

30. 13-5 • Solar Heating • Passive solar heating: absorbs and stores heat from the sun directly within a structure • Energy efficient windows and attached greenhouses face the sun to collect solar energy by direct gain • Walls and floors made of adobe, brick, stone, and water in metal or plastic containers hold heat and slowly release it throughout the day • Active solar heating: absorbs energy from the sun by pumping a heat-absorbing fluid through special collectors • Some of the heat is used directly, the rest is stored for later use in a large insulated container

31. 13-5 • Natural Cooling • Super-insulation • Light colored roofs (reflect as much as 80% of the sun’s heat) • Insulating garden-roofs • Suspend reflective insulating foil in upper floors to block heat entry • Earth tubes- place tubes underground in cool earth to naturally cool air

32. 13-5 • Solar Thermal Systems • Collect and transform radiant energy from the sun into high-temperature heat which can then be either used or converted into energy (most useful in desert areas with ample sunlight)

33. 13-5 Solar Thermal Systems • Central Receiver System • Power tower: computer controlled mirrors (heliostats) track the sun and focus sunlight on a central heat collection tower • Solar Thermal Plant • Sunlight is collected and focused on oil-filled pipes running through the middle of a large area of curved solar collectors • Generates temperatures high enough to produce steam for turbines and electricity • Use is limited due to high costs, limited sites, and lack of motivation due to availability of cheaper methods.

34. 13-5 • Solar cells: Photovoltaic (PV) Cells • a transparent wafer containing a semiconductor, flow of electrons creates electrical current • -can be incorporated into windows/roofs • -currently high prices; expected to fall • -currently only .05% of world's electricity • -Potentially 1/4 of world’s electricity by 2040

35. 13-5 • Flowing Water: • can be trapped by dams and released • to spin turbines and create hydropower • -Dams have high environmental impacts • Wind: wind turbines produce electricity • -Fastest growing source of energy, increased sevenfold since 1995

36. 13-5 • Biomass: Plant materials and animal wastes • Can be converted into gas or liquid biofuels • -Biogas, Liquid ethanol, liquid methane • -Burned to produce heat or electricity • -Biomass Plantations: utilize fast-growing trees • -Crop residues and animal manure can be converted into biofuels • -However burning biomass releases CO2

37. 13-6 • Geothermal Energy: heat stored in soil, underground rocks, and Earth's mantle • Can be used to heat and cool buildings • -Geothermal Heat Pumps: extract or store heat • very efficient and cost effective • -Geothermal Exchange(geoexchange): uses buried pumps filled with fluid to move heat • most cost effective, fuel efficient, and environmentally friendly method of heating/cooling

39. 13-6 • Geothermal Energy continued • -Dry steam, wet steam, & hot water can be used to generate electricity • -Molten rock, hot dry-rock zones, & warm-rock reservoir deposits: when molten rock heats subsurface rock, this heat energy can be used • -Disadvantages: • can be depleted, scarcity of suitable sites, air • pollution, high costs

40. 13-7 • Hydrogen: hydrogen gas could replace oil • in next century • -No CO2 emissions; low environmental impact • -Could be stored in pressurized tanks as liquid • hydrogen or in solid metal compounds • -Much safer than volatile gasoline, methanol, etc. • -Uses energy to produce it, so could be • nonrenewable if generated by fossil fuels • -High costs

41. 13-8 • Sustainable Energy Policies: • -Shift to smaller decentralized micropower systems such as wind turbines, fuel cells, & solar panels • -Combine energy efficiency and use of natural gas • -Reduce harmful effects of fossil fuels

42. 13-8 • Government Involvement: • Promote energy alternatives • -subsides • -taxes/tax breaks • -keep prices of resources artificially high/low