Chapter 9

• Environmental impacts of fossil fuels

  • Extraction phase
  • Transportation phase
  • Processing phase
  • Burning phase
• Coal stripmining


  • Huge environmental footprint
• Coal washing


  1. Water use and pollution

  2. Coal waste (toxic ash)

  3. Air pollution & climate change

  4. Landscape alteration and mine tailings
• Acid Mine Drainage


  Run-off released at certain types of mines can cause local increases in the acidity (pH <5) of soils, streams, and rivers – kill aquatic organisms and plants
• Acid mine drainage is associated primarily with the mining of coal deposits rich in the mineral pyrite (FeS2)
• Underground coal fires


  1. Can burn for 10s-100s years

  2. Significant contributions to CO2 emissions globally
• Conventional oil and gas extraction

  • Environmental concerns: Pollution by "extraction chemicals" into groundwater
  • Wastewater – large amounts of water is used in the process
  • Release of methane to surrounding geology – leak into ground water
• Unconventional gas extraction (hydraulic 'fracking')

  • Environmental concerns: Injection of large amounts of water and sand with very high pressure (or use of explosives) in shale rock – to decrease the porosity of the rock -> release the gas
  • Chemical additives (e.g. diesel, benzene) to lubricate extraction process
• Oil shipping


  Effect of oil spills in the ocean
• Worst oil spills in history

  • Deep-Water Horizon in Gulf of Mexico 2010 (>200 million gallons)
  • Exxon-Valdez oil tanker in Alaska 1989 (11 million gallons)
  • First Gulf war oil spill in Irak, Arabian Gulf 1991 (60-250 million gallons)
• Decrease in the number of oil spills
• Improved oil tankers


  Must be "double- hulled" and have separate ballast water tanks
• Refineries


  • Hazardous and polluting industry
  • Pollution: Air pollution – toxic gasses, VOC's (benzene, xylene etc)
  • Greenhouse gasses – Climate change
  • Wastewater – production water, cleaning effluents
  • Oil/petroleum spills
  • Explosions: Chemicals (petrochemicals)
  • Gasses (methane, hydrogen)
• BP Texas City Refinery 2005 – 15 dead, 170 injured
• Environmental impacts from burning coal and oil

  • Air pollutants
  • Climate change
  • Acid rain
  • Public Health Impacts
  • Thermal pollution
• Thermal Pollution


  From Power Plant Cooling
• Why coal is worse to burn than oil and gas: Environmental impact
• Air Pollution from fossil fuels

  • The Asian "brown cloud"—over eastern China
  • Air pollution hangs over New York City in this photo from the 1950s
• Primary vs Secondary Air Pollutants

  • CO
  • SO2
  • VOC's
  • NOx
  • PM10 & PM2.5
• Air pollutant


  A substance that is present in the atmosphere at a concentration that is sufficient to cause harm to humans, other animals, vegetation, or materials
• ~90% of air pollutants in US is caused by 5 primary pollutants, CO, SO2, NOx, VOC's, PM10&2.5
• Air Quality Index (AQI)


  A scale/index used to show how polluted the air is, along with the risks associated with each rating. An AQI is calculated using established standards based on medical research for the acceptable levels of major air pollutants.
• AQI


  • Serves two purposes: Inform the public about ambient air quality, so that they may take action to protect their health
  • Develop and assess policies for better air quality in countries
• AQI (0-500) is based on concentrations of typically: PM10, NO2, SO2, O3, CO, Pb, averaged over 8hrs or 24hrs
• The National Ambient Air Quality Standards for UAE correspond to 100 points in the AQI table, which is the level EAD has set to protect public health.
• Health effects from ambient air pollution

  According to WHO – 4-6 million deaths globally are linked to air pollution every year (that's 1 in every 8 deaths!)
• Physical activity affects the amount of air we breathe
• Particulate Matter (PM) in the atmosphere

  • Suspended particulate matter (PM) from both natural or anthropogenic sources
  • Anthropogenic sources: Forms through incomplete combustion (e.g. soot particles) e.g. in electric power-generating plants and from traffic
  • Natural sources: Dust particles from desert
  • Consists of: Aerosols particles <10m (e.g. soot, fine fly-ash); Particulates >10m (e.g. dust, fly-ash)
  • Diameters smaller than <10m is most dangerous for health - not filtered by hair or mucus in nose/throat; can reach deep into lungs and can be carrying adsorbed chemicals
• Industrial "smog" – "killer fog" (killed ~4000 people in a couple of days in London in the 1950's)
• High smokestacks


  Disperse the flue-gasses higher up where it gets dispersed quicker
• Pollution Control in Industry – PM removal


  • Cyclone separator
  • Electrostatic precipitators
  • Filter separator
• Cyclone separator


  Heavier particles "fall" out the bottom, lighter gas molecules go with the flow, 50-90% effective depending on particle size
• Electrostatic precipitators


  A more sophisticated approach, high voltage applied between negatively charged wire and two positively charged plates. Up to 99% effective also for smaller particles.
• Energy expensive: 2-4% of energy production goes towards the electrostatic precipitators
• SO2 emissions in the atmosphere causes acid rain


  1. SO2 + O2 + H2O => H2SO4 (Sulphuric acid)

  2. Sandstone and marble buildings erode (sandstone contain CaCO3 that reacts with acid)

  3. Ecosystem impacts

  4. Impacts on buildings
• Values of pH in precipitation falling in the US during the early 21st century. More heavy industry = more SO2 emissions
• Pollution Control in Industry - SO2 removal


  1. Flue-gas desulfurization (scrubbing) to remove SO2 from flue gasses: SO2 in flue gases pass through a slurry of water mixed with pulverized limestone (CaCO3) or dolomite [CaMg(CO3)2]

  2. SO2 + CaCO3 => CaSO3 (gypsum) + CO2

  3. Can remove up to 98% of SO2 emissions

  4. Expensive to install (15-20% of total cost)

  5. Energy cost up to 8% of total production

  6. Large amounts of sulphureous waste (gypsum)
• Carbon Monoxide


  • The main anthropogenic source is from incomplete combustion of gasoline/diesel in automobile engines
  • Although CO is one of the most abundant air pollutants, it is not very toxic at the levels usually found in the atmosphere (0.1ppm) => kept stable by conversion to CO2 by *OH; and by microbial conversion in soils
  • However, in cities – congested with traffic – lack of 'natural defense' as not much soil in city – CO levels can be high
  • In confined spaces CO can cause serious health problems (even death through asphyxiation)
  • CO interferes with the oxygen-carrying capacity of blood
• Nitrogen Oxides (NOx)


  • Practically all anthropogenic NOx enter the atmosphere from the combustion of fossil fuels by automobiles, aircraft, and power plants
  • N2 reacts with O2 at high temp forming NO* that is converted to NO2 after further reaction with O2
  • Far more NOx are released to the atmosphere by natural processes than by human activities, but in congested areas it can be noticable
  • NO2, regardless of its source, is ultimately removed from the atmosphere as nitric acid (acid rain) and nitrates in dust and rainfall
  • Acid Rain: 4NO2 + H2O + O2 => 4HNO3 (secondary air pollutant)
  • NO2 can cause irritation of the eyes, inflammation of lung tissue, and emphysema
  • NOx gives the red/brownish color of photochemical smog
• Volatile Organic Compounds (VOC's)


  • A great variety of VOC's, including hydrocarbon's, enter the atmosphere from both natural and anthropogenic sources
  • The petroleum industry is the main anthropogenic source of HC's in the atmosphere
  • 85% of global emissions of VOC's is from natural sources (e.g. pine forests), rest is from anthropogenic sources
  • VOC's react with other substances in the atmosphere to form the secondary air pollutants associated with photochemical smog