Nonrenewable Energy Resources

1. Nonrenewable Energy Resources • 99% of the energy that heats the earth and our buildings comes from the sun, the remaining 1% comes mostly from burning fossil fuels. • 78% of the commercial energy (sold in market) we use comes from nonrenewable fossil fuels • Burning fossil fuels causes more than 80% of US air pollution and more than 80% CO2 emissions.

2. Questions to Keep in Mind • What is the net energy yield for the resource? • How much will it cost to develop or phase in and use? • What constructive subsidies will be used to promote R&D? • How will dependence on the resource affect national and global economic and military security? • How vulnerable is the resource to terrorism? • How will extracting, transporting, and using the resource affect (a) environment; (b) human health; (c) climate • Should true costing be considered?

3. Net Energy Net energy is the amount of high-quality usable energy available from a resource after subtracting the energy needed to make it available for use. Net energy ration = useful energy produced:energy used to produce it ie. 10:8 (10/8) for every 10 units of energy in oil we have to use and waste 8 units of energy. The net energy ratio is 10/8 or 1.25. The higher the ratio, the greater the net energy. When the ratio is less than 1, there is a net energy loss.

4. COAL • Coal is an abundant energy resource that is burned mostly to produce electricity and steel. • Coal is the world’s most abundant fossil fuel. • Mostly in USA (25%), Russia (16%), and China (12%) • US coal reserves could last up to 300 years, but an increase of just 4% per year could reduce that to 64 years!

5. COAL FORMATION

6. Advantages of Coal • Abundant known world reserves (200 years at current world consumption rate) • Unidentified world reserves (1000 years at current consumption rate) • USA (300 years at current consumption rate) • High Net Energy Yield • US subsidies keep prices low

7. Disadvantages of Coal • 60 % surface mined (strip mining) in USA • 40 % subsurface mined • Occupational hazards include “black lung disease”, underground fires and collapse. • 20% of coal becomes fly ash, boiler slag, and sludge. Releases mercury and radioactive particles into air. • Expensive to process and transport

8. Environmental Impacts From Coal • Releases CO into atmosphere • Contributes 35% of all CO2 into atmosphere (global warming) • Contributes 70 % of all SO2 (acid deposition) • Contributes 30% of all NO andNO2 (acid deposition) • Produces more fly ash, toxic metals, and radioactive particles than a nuclear power plant.

9. Solid Coal Converted to Gas and Liquid Fuels • Coal can be converted to synthetic natural gas, methanol (CH3OH), or synthetic gasoline through coal liquefaction (synfuels). • Advantages: easily transported through pipelines, produces less air pollution, large supply. • Disadvantages: low net energy yield, expensive to build plants, acceleration of coal depletion, large amounts of water required, releases large amounts of CO2, more expensive than coal, mercury and PAH’s released into environment.

10. Coal Gasification

11. Coal Liquefaction

12. Acid Deposition SOx • Sulfur in the atmosphere comes from burning bituminous coal, smelting, and organic decay. • 90% is from human sources. • Sulfur in the atmosphere combines with water vapor to form hydrogen sulfite gas. • SO2 (s) + H2O (v) H2SO3(v) • Hydrogen sulfite reacts with oxygen gas to form sulfuric acid. • H2SO3 + ½ O2 H2SO4

13. Acid Deposition NOx • Major sources of nitrogen oxides include combustion of coal, oil, natural gas, forest fires, bacterial action in soil, volcanic gases, and lightening-induced atmospheric reactions • Nitrogen monoxide reacts with oxygen gas to produce nitrogen dioxide gas • NO(v) + ½ O2(v) NO2(v) • Nitrogen dioxide reacts with water vapor in the atmosphere to produce hydrogen nitrite and hydrogen nitrate • 2NO2(v) + H2O(v) HNO2 (v) + HNO3(v)

15. Effects of Acid Deposition on Aquatic Ecosystems • Below a pH of 4.5, most fish cannot survive • Acid deposition releases Al3+ ions attached to soil particles into nearby lakes. These ions asphyxiate many fish, causing excess mucous formation which clogs their gills • Norway, Sweden, Canada and Northeastern USA have 1000’s of “fishless” lakes because they are downwind of coal burning plants.

16. Effects of Acid Deposition on Forests • Forests and crops are harmed by leaching essential plant nutrients such as calcium and magnesium salts from soils. This reduces the plants productivity and the ability of soils to buffer or neutralize acid inputs. • Acid deposition weakens trees and makes them more susceptible to other stresses such as severe cold, diseases, insect attacks, drought, and harmful mosses. • Cloud forests are hardest hit from sitting in acid clouds. These areas often have thin soils with little buffering capacity.

18. Effects of Acid Deposition on Human Health and Culture • Contributes to human respiratory disease (bronchitis and asthma) • Contributes to toxic metal leaching such as copper from water pipes. • Damages statues, national monuments, buildings, car finishes, and grave headstones.

19. Climate Change • Water vapor (H2O), carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) influence climate by warming the lower troposphere and the earth’s surface.

20. Greenhouse Effect Natural Greenhouse Effect – without it the planet would be a cold and mostly lifeless planet Incoming wave = visible light wave (short wave) Outgoing wave = infrared wave (long wave)

21. “Unnatural Greenhouse Effect” There is a high probability (90-99%) that increasing concentrations of greenhouse gases in the troposphere are from burning fossil fuels, deforestation, and agriculture.

22. Temperature Changes • Past temperature changes are estimated by the analysis of radioisotopes in rocks and fossils, plankton and radioisotopes in ocean sediments, ice cores from ancient glaciers, tree rings, and historical records.

23. Absorption of Radiant Heat due to CO2 in Atmosphere

24. Methane Increases in the Atmosphere

25. Nitrous Oxide Increases in Atmosphere

26. Oceans Moderate Global Temperature • The oceans help moderate global temperatures by removing 29% of the excess CO2 we pump into the atmosphere as part of the anthropogenic carbon cycle • The oceans also absorb heat from the atmosphere and slowly transfer it to the deep ocean. • Ocean currents act as giant convection convection currents transferring heat from the equator to the poles.

27. Other Synergistic Effects From Outdoor Air Pollution • Increased CO2 in the troposphere could increase photosynthesis, but this would only be temporary. • Aerosols and soot produced by the burning of coal and other fossil fuels can warm or cool the atmosphere. • Warmer air can release methane gas stored in bogs, wetlands, and tundra soils and make the air even warmer.

28. Effects of Global Warming • Agricultural changes ( shifting food-growing areas, changes in crop yields, increased irrigation demands, increased pests, diseases and weeds in warmer latitudes.) • Water Resources (changes in water supply, decreased water quality, drought, flooding, snowpack reduction, melting of glaciers)

29. Effects of Global Warming • Forests (shifts and changes in composition, disappearance of high altitude forests, increased forest fires, loss of wildlife habitat and species). • Biodiversity (Extinction of some plant and animal species especially those in high latitude biomes, loss of habitat, disruption of aquatic life)

30. Effects of Global Warming • Sea Level and Coastal Areas (rising sea levels, flooding of low lying islands and coastal cities, estuaries, wetlands, and coral reefs, beach erosion, disruption of coastal fisheries, aquifer salt water intrusion). • Human Health ( disruption of food and water supplies, spread of tropical diseases to temperate areas, increased deaths from heat, increased water pollution from coastal flooding).

31. Effects of Global Warming • Human Population (Increased deaths from heat and disruption of food supplies, increased environmental refugees, increased migration). • Weather Extremes (prolonged heat waves and droughts, increased flooding from more frequent, intense and heavy rainfall events in some areas).

32. Air Temperature Increases

34. Partial Solutions • Particle Emission Control Devices 1. Electrostatic Precipitator – utilized for fly ash reduction and to remove particulate emissions by treating air with an electrical charge to capture the suspended particles in the gas flow. The particles are collected on an array of charged parallel plates above the collection hoppers in the precipitator box.

35. Electrostatic Precipitator

36. Partial Solutions 2. Scrubbers (wet and dry) – are used to trap particles from gaseous emissions from fossil fuel burning power plants especially. The scrubbers prevent most of these particles from entering the atmosphere especially NOx and Sox, where they can change into environmentally damaging acid deposition.

37. Wet Scrubber

38. Partial Solutions • Fluidized Bed Combustion – use heated beds of sand-like material suspended (“fluidized”) within a rising column of air to burn many types and classes of fuel. This technique results in a vast improvement in combustion efficiency of high moisture content fuels. • The scrubbing action of the bed material on the fuel particles enhances the combustion process by stripping away the CO2 and char layers that normally form around fuel particles. This allows O2 to reach the combustible material much more readily and increases the rate and efficiency of the combustion process.

39. Fluidized Bed Combustion • Combustion example, the burning of propane is:C3H8 + 5O2 → 3CO2 + 4H2O

40. PREVENTION IS BEST! Maldives