PHYS 1211 - Energy and Environmental Physics

1. PHYS 1211 - Energy and Environmental Physics Lecture 11 Fossil Fuels - 2 Michael Burton

2. This Lecture • Energy Content of Fossil Fuels • Problems with Fossil Fuels • Production issues • Pollution • Availability

3. Hydrocarbons • Fossil fuels contain hydrocarbons — molecules containing hydrogen and carbon. • CnHm • e.g. CH4 (methane), C5H12 (pentane), C6H6 (benzene) • When the fuel is burnt in oxygen the carbon combines with oxygen to make CO2 and the hydrogen combines with oxygen to make H2O.

4. Burning Hydrocarbons • Methane CH4 CH4 + 2O2 CO2 + 2H2O • Pentane C5H12 C5H12 + 8O2 5CO2 + 6H2O The energy released in these reactions varies for different hydrocarbons.

5. Energy Content of Fuels * Not a fossil fuel # Other oil products such as Diesel, Avgas, Fuel oil are similar.

6. Hydrogen Hydrogen (H2) has the highest energy content of any fuel. It is used to fuel the space shuttle and Europe’s Ariane 5 rocket. However, it is not a naturally available fuel.

7. Hydrogen to Carbon The more hydrogen atoms relative to carbon atoms in a fuel the higher its energy content. So methane (CH4) the main constituent of natural gas with four carbons to every hydrogen has the highest energy. Oil products (e.g. octane C8H18) typically have just over two hydrogen atoms per carbon and have less energy. Coal with a little over one hydrogen per carbon has low energy. Ethanol (C2H5OH) is also quite low since it contains oxygen and so is already partly oxidised.

8. Hydrogen to Carbon More Hydrogen More Carbon Natural Gas Oil Coal More Energy per kg

9. Octane Rating of Fuels • Liquid Fuels (e.g. Petrol) are also classified according to their “octane rating”. • This is an often misunderstood quantity. • Octane rating is unrelated to the energy content of the fuel. • Despite the fact that “high octane” seems to have entered our language with the meaning of “high energy” • Octane rating is also not a measure of the quantity of octane (C8H18) in the hydrocarbon mix.

10. Octane Rating • Octane rating measures the resistance of a fuel to predetonation (also known as “knock” or “pinging” or “pinking”). • This occurs when the fuel mixture in the engine is ignited as a result of compressional heating, rather than by the spark plug. Heating by adiabatic compression (see lecture 5)

11. Octane Rating • This predetonation effect can reduce performance and in some cases cause damage to the engine. • The problem is increased for higher compression ratio engines, which offer higher engine performance. • Cars with these engines may need to use higher octane fuel. • However there is no advantage in using higher octane fuel in a engine designed for regular fuel.

12. Octane Rating • The octane rating of a fuel is determined by the mix of hydrocarbons, and by additives. • A widely used “anti-knock” additive was tetraethyl lead (CH3CH2)4Pb. • However, concern about the toxicity of the lead has resulted in the phasing out of leaded petrol for motor fuel in most countries. • Tetraethyl lead is still used in aviation fuels.

13. Problems with Fossil Fuels • Problems associated with Production • Accidents (coal mining, oil rig explosions) • Pollution (e.g. oil spills) • Pollution and Health Problems due to Use • Sulfur dioxide, nitrogen dioxide (producing particulates or aerosols) • Climate Change • Greenhouse Gases (Mostly CO2) • Availability issues • “Peak Oil”

14. Coal Mining Deaths • UK Coal Mining Deaths (1873-1953) • 85,745 (average 1058 per year) • China Coal Mining deaths (2000-2009) • 51,267 (average 5126 per year) Rescuers prepare to go into a coal mine to search for stranded miners in Hebi City, central China's Henan Province, in the early morning of October 3, 2005. A gas explosion occurred at 4:45 a.m. Monday in the coal mine belonging to the Henan Hebi Coal (group) company, claiming 34 lives. The cause of the accident is still under investigation. (Chinese Peoples Daily)

15. Recent Events Pikes River coal mine explosion (2010) in New Zealand (29 deaths) BP Deepwater Horizons oil rig explosion (Apr 2010) caused 11 deaths and a major oil spill with 4.9 billion barrels of oil released into the Gulf of Mexico.

16. Pollution Due to Fossil Fuel Use Pollution due to fossil fuel burning can be: • Greenhouse pollution • Primarily due to CO2 which is an inevitable product of hydrocarbon burning. • CH4 and N2O are also greenhouse gases. • Main cause of global warning. • Other Pollution • Toxic gases such as CO, SO2, Nitrogen oxides. • Particulate pollution. • Acid Rain. • Cause health problems and other environmental damage.

17. London Smog • London smog - a frequent occurrence in the early 20th Century. • Caused by extensive burning of coal for heating. • The “great smog” of 1952 caused 12000 deaths. • Led to the Clean Air Act of 1956. • Introduced smokeless zones where only smokeless fuels could be used • e.g. Anthracite, Coke.

18. Pollution • Pollution can arise from: • Sulfur dioxide • Coal and oil contain about 1% of sulfur that burns to make sulfur dioxide (SO2). • Nitrogen oxides • Nitrogen in fossil fuels burns to produce nitrogen oxides including N2O (Nitrous oxide) and NO2 (Nitrogen Dioxide). • Carbon Monoxide • Incomplete burning of fuels can produce CO. • Heavy Metals • Trace elements in coal contribute to pollution including mercury, arsenic, lead and other heavy metals.

19. Acid Production • Sulfur dioxide and nitrogen oxides can undergo further reactions. 2SO2 + O2 2SO3 SO3 + H2O  H2SO4 (sulfuric acid) NO2 + OH  HNO3 (nitric acid)

20. Acid Rain These acids dissolve in rain producing the phenomenon of acid rain. Even unpolluted rain is slightly acidic because of dissolved CO2. It has a typical pH of 5.6 (where 7 is neutral and low numbers are acidic). In industrial areas rain with pH of 4 is not uncommon.

21. Acid rain has damaging effects on natural vegetation and forests and on freshwater ecosystems. Build up of acid in lakes can lead to loss of fish populations. Acid Rain Trees killed by acid rain pH of rain in eastern US.

22. Sulfate Aerosols • The sulfuric acid from fossil fuel pollution forms tiny particles that remain suspended in the air. • These are known as sulfate aerosols. • Sulfate aerosols have a significant effect on the climate. • They reflect sunlight back to space and have a cooling effect. • They also contribute to “fine particle pollution”

23. Fine Particle Pollution • “Fine particle” or “particulate” pollution is due to tiny particles less than 10mm (0.01mm) in diameter. • These can be sulfate aerosols or solid particles of ash or soot. • Burning of fuels is a major source. • Particulates are a serious health problem. • The particles are small enough to lodge deep in the lungs and do substantial damage.

24. Fine Particle Pollution • Measured by PM10 index. Particles of 10 mm diameter or smaller in mg m–3 • Or: • PM2.5 index. Particles of 2.5 mm diameter or smaller in mg m–3

25. Health Effects • Statistically high levels of fine particle pollution (PM10 or PM2.5) can be linked to: • High death rates from respiratory and cardiovascular causes - including strokes. • Increased number of heart attacks. • Increase in severe asthma attacks. • Increased risk of lung cancer. • Many other respiratory health problems.

26. Air Pollution • Air pollution from coal fired power stations in the USA is estimated to cause about 30,000 deaths per year. (Abt Associates report, 2000) • The WHO estimates that world-wide deaths from outdoor air pollution are 865,000 per year. • India 120,600 deaths per year • China 275,600 deaths per year

27. Fine Particle Pollution US/Australian standard

28. Air pollution Jul 20 – 2014 http://aqicn.org

29. Pollution is worst in developing countries where environmental regulations are not strong. However, significant pollution problems still exist in developed countries Cairo — World’s most polluted city. Smog in Los Angeles

30. Air Quality Standards Standards have been established for many air pollutants. For example:

31. pollution biomass burning SCIAMACHY Tropospheric NO2

32. Shipping NO2 in GOME-2 data • Pattern of shipping NO2 close to Somalia has changed in 2007 • Probably as an attempt to evade pirates

33. Controlling Pollution • Pollution in the developed world has been significantly reduced by “clean air” policies. • These have included. • Emission controls for cars including the fitting of catalytic converters, and use of unleaded fuel. • Incorporation of technology to limit sulfur emissions and particulates from fossil fuel power stations.

34. Controlling Pollution Scrubbers remove SO2 from power station exhaust gases by passing the gas through a slurry of calcium carbonate (crushed limestone) in water. The SO2 reacts with the carbonate to make Calcium sulfate. Electrostatic precipitators remove particulates from power station exhaust gases by charging the particles and passing the gas through an electric field.

35. Greenhouse Pollution • Greenhouse pollution is the release of the gasses that contribute to global warming through the greenhouse effect. • The main source of greenhouse pollution is the CO2 produced by fossil fuel burning. • Methane (CH4) is also a greenhouse gas so unburnt natural gas dues to leakage or incomplete combustion also contributes. • Nitrous oxide (discussed earlier) is also a greenhouse gas.

36. Greenhouse Gases GWP is relative global warming potential compared with CO2

37. CO2 (Keeling Curve) Build up of CO2 accounts for only about half of CO2 produced (e.g. by fossil fuel burning).

38. CO2 Production • Methane CH4 CH4 + 2O2 CO2 + 2H2O • Pentane C5H12 C5H12 + 8O2 5CO2 + 6H2O CO2 is a normal product of burning any hydrocarbon fuel.

39. Hydrogen to Carbon More Hydrogen More Carbon Natural Gas Oil Coal More Energy per kg More CO2 Pollution

40. CO2 From Fossil Fuels Coal is the dirtiest fuel in terms of CO2 production per unit of energy. Natural Gas is the cleanest, and oil is intermediate.

41. Carbon Capture and Storage • Can we remove CO2 from power station emissions in the same way as scrubbers remove SO2? • This is the idea behind Carbon Capture (Carbon Sequestration) or so called “clean coal” technologies. • If we can do this we can continue to use coal while complying with greenhouse gas reduction targets. • For Australia with abundant coal reserves this is very attractive.

42. Carbon Capture and Storage • While sulfur is a trace constituent, carbon is one of the main components of the fuel. • There is a lot more material to remove and store. • Such schemes will involve: • Capture of the carbon dioxide from the exhaust gases. • Transport to a suitable storage location. • Long term storage in a way that will not allow CO2 to leak into the atmosphere.

43. Carbon Capture • Carbon dioxide can be captured by dissolving in an organic solvent that selectively absorbs CO2. • The CO2 can then be released from the solvent by heating it.

44. Transport • CO2 could be transported by pipeline. • Alternatively it could be compressed and transported as a liquid • Similar to transportation of liquid petroleum gas.

45. Carbon storage The CO2 can be stored underground in locations such as depleted oil and gas reservoirs.

46. Hubbert’s Peak • In 1956 US Geologist M. King Hubbert predicted that US oil production would peak in the early 1970s. • His prediction was ridiculed by experts at the time, but until recently had proved correct. US oil production peaked in 1971 and was in decline up to 2008.

47. “Peak Oil” Applying the same methods to world oil production predicts that we are now close to the peak (so called “Peak oil”) This implies that we have burnt about half the world’s total oil supply. Since demand for oil is continuing to rise: Price of oil should rise steeply when the peak is reached. Is this what we are seeing now? Demand for oil After peak production will fall Oil Production

48. Oil Prices to 2009

49. US Oil production is now increasing again (due to unconventional oil sources)

50. Are we really near the Peak? • Current proven oil reserves should last for about 54 years at current production rates. • In 2008 the figure was 41.6 years. • We are finding new reserves of oil much faster than we are using it. • So many experts argue that there is plenty of oil. • Higher prices will make it economic to explore in more remote areas (the arctic and deep ocean) and extract oil from sources such as oil shales (oil source rock not yet “cooked” into oil). We have already seen the example of oil from tar sands. • Even if they are correct we will still likely to have to adjust to considerably higher oil prices.