Introduction to Fracking
In our previous chapters, we looked at how fossil fuels like coal, petroleum, and natural gas are formed over millions of years. Usually, these fuels are found in "pockets" underground that are easy to reach. However, a lot of gas and oil is actually trapped inside a specific type of rock called shale.
Because shale is an impermeable rock (meaning water and gas cannot easily pass through its pores), we cannot just pump the fuel out like a normal well. We have to use a special technique called fracking. In these notes, we will explore how this works and why people have different opinions about it.
Don't worry if this seems technical! Just remember: Fracking = "Fracturing" or cracking the rock to let the gas out.
What is Fracking?
Fracking is the common term for hydraulic fracturing. It is defined as the process of extracting natural gas or petroleum from shale rock by using high-pressure liquid to crack the rock open.
How it works: A Step-by-Step Guide
1. Drilling: A deep well is drilled vertically down into the ground. Once it reaches the layer of shale rock, the drill turns sideways (horizontally) to go through the shale layer.
2. Injection: A mixture of water, sand, and chemicals is pumped down into the well at extremely high pressure.
3. Fracturing: The high pressure causes the shale rock to crack or "fracture."
4. Propping: The tiny grains of sand in the mixture stay in the cracks to "prop" them open so they don't close back up.
5. Extraction: The gas (mostly methane, \(CH_4\)) or oil can now escape through the cracks, flow into the pipe, and be collected at the surface.
Quick Tip: Think of a juice box. If the straw is blocked, you can't get the juice. Fracking is like squeezing the box so hard that it cracks, allowing the juice to leak out into a place where you can catch it!
The Benefits of Fracking
Why do countries use fracking? There are several economic and social advantages:
1. Access to more resources: It allows us to reach non-renewable energy sources that were previously impossible to get. This increases the total supply of fossil fuels.
2. Energy Security: Countries can produce their own gas and oil rather than relying on importing it from other nations. This makes their energy supply more stable.
3. Lower Energy Costs: Increasing the supply of natural gas usually makes it cheaper for people to heat their homes and for factories to run.
4. Economic Growth: The fracking industry creates many jobs for local people and brings money into the local economy through taxes and investment.
The Limitations and Environmental Impacts
Fracking is controversial because it can cause significant environmental problems:
1. Water Consumption: The process requires millions of liters of fresh water, which can put a strain on local water supplies, especially in dry areas.
2. Groundwater Contamination: There is a risk that the chemicals used in the fracking fluid, or the methane (\(CH_4\)) gas itself, could leak into aquifers (underground water stores), making the water undrinkable (non-potable).
3. Seismic Activity: The high pressure used to crack the rocks and the disposal of waste liquid can cause small earthquakes (tremors). While usually small, they can worry local communities.
4. Finite Resource: Like all fossil fuels, the gas and oil from fracking are finite. This means they will eventually run out and are not a long-term sustainable solution to our energy needs.
5. Air Pollution: Methane can leak from the wells. Methane is a powerful greenhouse gas that contributes to the enhanced greenhouse effect and global warming.
Did you know? Shale is a sedimentary rock that we classified in Section 1.1 as impermeable. This is exactly why we need to crack it; if it were permeable, the gas would have escaped on its own long ago!
Summary: Key Takeaways
To do well in your exam, make sure you can discuss both sides of the fracking debate. Use this table as a mental checklist:
Benefits:
- Increases energy supply.
- Makes gas cheaper.
- Creates jobs and wealth.
- Improves energy security for a country.
Limitations:
- Uses huge amounts of water.
- Risk of polluting drinking water.
- Can cause small earthquakes.
- Still produces greenhouse gases and is non-renewable.
Common Mistakes to Avoid
- Don't confuse fracking with "renewable" energy. Even though it's a newer technology, it still extracts fossil fuels which are finite.
- Don't forget that fracking involves horizontal drilling, not just vertical drilling.
- Don't worry about specific case studies. The exam will give you the information you need about a specific place—you just need to know the principles of how fracking works and its pros/cons.
Quick Review Question: Why is sand added to the fracking fluid?
Answer: To "prop" open the cracks in the shale rock so the gas can continue to flow out.