Unit 6.3 - Fuel Types and Uses

Question 1

Subsistence Fuels

Answer 1

• Biomass fuel sources that are easily accessible (can be found and gathered at hand) - often used in developing countries as a home heating ot cooking fuel
• wood andcharcoal are two of the most common fuel sources in developing nations
  - wood is cheap/free to cut down and utilize as fuel - can cause deforestation and habitat loss
  - charcoal is made by ehating wood unmder low oxygen conditions for a long time
• peat is partially decomposed organic matter (often ferns or other plants) found in wet, acidic ecosystes like bogs and moors
  - can be dried and used as a biomass fuel source

Question 2

Coal formation

Answer 2

• pressure from ovrlying rock and sediment layers compacts peat into coal over time
• in order of energy density and quality: lignite - bituminous - anthracite
  - the deeper a coal reserve is buried, the more pressure from overlying rock layers and the more energy dense
• because higher energy density means more energy released when a fuel source is burned, anthracite is the most valable form of coal (highest quality)
  - coal is burned to heat water into steam, to turn a turbine that generates electricity
  - more dense coal - hotter/longer fire = more steam = more electricity

Question 3

Natural Gas

Answer 3

• Decaying remains of plants and animals (mostly marine life) are buried under layers of rock and converted by pressure into oil (petroleum) and natural gas over time
• Natural gas is mostly methane (CH4) and is found on top of trapped oil (petroleum) deposits
• forms when oil is trapped in porous, sedimentary rock, underneath a harder, impermeable rock layer that doesnt let the gas escape
• considered teh “cleanest” fossil fuel (produces fewer air pollutants and least CO2 when burned)
• produces about .5 as much CO2 as coal when burned to generate electricty
• produces virtually no PM (ash/soot)
  - produces far less SOx, NOx, than coal or other oil, and NO MERCURY

Question 4

Crude Oil (petroleum)

Answer 4

• Decaying organic matter trapped under rock layers is compressed into oil overtime
• extracted by drilling a well through the overlying rock layers to reach the underground deposit and then pumping liquid out under pressure
• can also be recovered from tar sands (combination of clay, sand, water, and bitumen)
• Bitumen is a thick, sticky, semi-soild form of petroleum (no liquid)
• extracting and using oil from tar sands is extrmely energy and water intensive
  - lots of water needs to be heated (requirings energy) to create steam thats piped down into the tar sand to melt the bitumen into a laquid that can flow up a pipe
  - lots more water is used to seperate the oil from all of the impurities (sand, clay) at the refinery

Question 5

Fossil Fuel Products

Answer 5

• Crude oil (petroleum)is converted into lots of different propducts through the process of fractional distilation
• crude oil is burned in a furnace and vapor passes into a column where different hydrocarbons are seperated based on their boiling points
• Hydrocarbons with lower boiling points gather at the top of the column, higher boiling points gather at the bottom
• different hydrocarbons within petroleum are used for different products:
  - petroleum gas
  - gasoline (fuel for cars)
  - Naphtha (used to make plastic)
  - Jet fuel
  - diesel fuel
  - motor oil
  - bitumen (asphalt for roads)