Science - Fossil Fuels & Nuclear Energy

What are fossil fuels?

Fossil fuels- nonrenewable carbon-based resources formed between 150-300 million years ago from remains of dead organisms

• Coal, petroleum (oil), natural gas

Combustion Reaction?

• When carbon and hydrogen atoms from a fossil fuel combine with oxygen from the air to form carbon dioxide and water.

• Converts chemical potential energy stored within bonds of fossil fuel into thermal energy

Oil (Petroleum)

• Partially decomposed ancient marine microorganisms sunk to ocean floor and over time, were buried under layers of sediment and rock.  

• Made up of a mixture of hydrocarbons

What does oil and natural gas start life as?

Microscopic plants and animals that lives in the ocean

Locating Oil - Seismic Waves

Seismic surveys are used to locate likely rock structures

  underground in which oil and gas might be found

• Shock waves are fired into the ground. These bounce off layers of rock and reveal any structural domes that might contain oil

Exploration & Production Drilling the Well

Once an oil or gas prospect has been identified, a hole is drilled to assess the potential oil

• The cost of drilling is very great.  On an offshore rig, it may cost $10,000 for each meter drilled.

• A company incurs vast losses for every “dry hole” drilled

Exploration and Production Transport

Once extracted, oil and gas must be sent to a refinery for processing

• Pipelines transport most of the world’s oil from well to refinery

• Massive Oil Tankers also play an important role in distribution

Oil is used for what?

• Transportation Fuels (gasoline)

• Electrical generation

• Asphalt

• Plastic!

Natural Gas

• Formed in the same way that oil forms

  • Due to density differences, natural gas is found trapped on top of petroleum deposits

• Composed of mostly methane, but could also contain butane or propane

Natural Gas

• Contains more chemical potential energy per kg than coal or oil- more efficient 

• Produces less CO₂ (pollutants) than oil or coal when burned

• Uses: Cooking, heating homes, 

manufacturing

• Colorless and odorless

What is fracking?

• Hydraulic fracturing (fracking) uses chemically treated high pressure water to break apart rock containing natural gas

• Risks include contamination of ground water & air pollution from methane release

Coal

• Decomposing swamp plants buried under mud with no oxygen, these remains produced peat.

• Peat=partially decayed vegetation

• Over time, increased pressure & heat transformed this peat into the coal we use

Why use coal?

• Safer to ship, cheaper to extract, abundant in US

  • Wyoming, Appalachian 

Mountains hold majority of US coal

• Inexpensive

Cost of coal?

• More air pollution than any other fossil fuel

  • CO₂ released into the atmosphere -> global warming

• Extraction= lots of environmental damage

  • Many hazards associated with mining

Parts of an atom

• A stable atom has the same number of protons and neutrons

• An isotope has more or less neutrons- some isotopes are radioactive

• Example: Uranium-235

Fussion vs. Fission

• Both processes release a tremendous amount of energy

• Fusion not practical to use for production of energy

Fusion is 2 atoms combined into 1, fission is 1 atom combined into 2

Nuclear fuel for fission reactions

Nuclear power plants use the isotope of Uranium called Uranium-235 because the atom is easy to split

Nuclear Fission Chain Reaction

When U-235 nucleus is split, neutrons are released

- These free neutrons can go on to split other U-235 nuclei

- Neutrons can be absorbed by control rods to prevent them from splitting other nuclei, thus controlling the chain reaction

Where are nuclear power plants?

- Located in 30 countries

- About 450 Nuclear Reactors total

- 60 new power plants under construction