APES 6.5 Fossil Fuels

Enduring Understanding:

Humans use energy from a variety of sources, resulting in positive and negative consequences.

Learning Objective:

Essential Knowledge:

The combustion of fossil fuels is a chemical reaction between the fuel and oxygen that yields carbon dioxide and water and release energy.
Energy from fossil fuels is produced by burning fuels to generate heat, which then turns water into steam. That steam turns a turbine which generates electricity.
Humans use a variety of methods to extract fossil fuels from the earth for energy generation.
Hydrologic fracturing (fracking) can cause groundwater contamination and the release of volatile organic compounds.

Process and Production of Electricity

Coal has to be dug out of the ground
Its viability for extraction depends on how deep it is found in a certain location
There are two types of coal mining: Surface mining and subsurface mining
- Surface mining involves digging a little bit of land out to access coal below a relatively small amount of soil
- This causes the removal of topsoil which is an important habitat
- Subsurface mining will need tunnels deep in the earth to extract
- Also destroys habitat
- Can be very dangerous
- Not done as frequently because of safety concerns around the miners who have to go down into the mines

Combustion is a chemical process where fuel is burnt in the presence of oxygen
- H2O and CO2 are byproducts
Coal, oil, and natural gas go through very similar processes
Coal is pulverized before it reaches combustion
- Other fossil fuels may go through other, similar kinds of preparation
The fuel is then burnt, which produces heat
The heat is directed into water, which vaporizes and becomes high pressure steam
The steam is then used to turn a turbine, from which the mechanical energy goes into a generator as electricity
The electricity is distributes or stored for the community/other uses
There needs to be a source of water to produce the steam
- There needs to be water for the production of steam
- You also need water for cooling so that the equipment doesn’t overheat
- This can be a river, a lake, a reservoir, etc.

Used to extract natural gas from the ground
Layers of rock can also contain groundwater near gas reserves
- The extraction can contaminate the groundwater
This process starts with making a well made with cement lining in hopes that anything running through it will not contaminate groundwater
A pipe is then inserted to access the natural gas
- Through the pipe they pump fracking fluid which contains sand and many chemicals
This increases pressure which fractures the ground, releasing the gas and allowing it to be piped out

The initial process of making the well and clearing the area destroys habitats and contaminates water
- An improperly lined pipe can also lead to contamination
Fracking fluid contains Volatile Organic Compounds (VOCs)
- These vaporize at room temperature, which aren’t a problem in the ground but can be a problem in the atmosphere, land, and water
Natural gas leakage can occur
The breakage of rock and increased pressure leads to earthquakes
- Even properly sealed wells can break from these earthquakes and lead to all of the aforementioned contamination concerns
Uses lots of water

The mining process (digging and extraction) can cause the destruction of habitats, and machinery using gasoline are used
The pulverization of the coal is dangerously flammable and can be dangerous to human lungs
The large use of water can deplete habitats and water as a resource
CO2 is emitted, contributing more greenhouse gases and the greenhouse effect globally
There are other pollutants released such as mercury and sulfur that will end up in other places after it rains and the impurities are deposited