Sustainability of Energy

Question 1

How does fracking work

Answer 1

A well is drilled into the rock, as shale is deposited in layers when the drill reaches the shale, it turns to 90 degrees and a horizontal well is created. This can be up to 2 miles down. Due to the tiny pore spaces in shale rock, water, sand and chemicals are injected, cauing small fissures (cracks) to form. The force of the water creates fissures (hydraulic fracturing), sand keeps them open and chemicals dissolve minerals and prevent corrosion of the pipes and well. Methane flows through fissures and out of the well and is used to generate electricity. Around 40% of chemicals and water returns to the surface where it is treated.

Question 2

What are 3 benefits and 3 disadvantages of shale gas

Answer 2

• It is the cleanest burning fossil fuel, so much better than oil or coal.
• Gives countries their own source of gas rather than relying on russia or the middle east.
• produces many jobs in a reclining sector.
• it is still a fossil fuel and so does release co2
• all the wastewater cannot be extracted and there are concerns it could infiltrate groundwater stores or aquifiers.
• fracking uses huge amounts of water

Question 3

What are the sources of hydrogen gas

Answer 3

Natural gas, coal, water, biomass

Question 4

What are the 4 methods of producing hydrogen energy from the four sources

Answer 4

1. Steam methane reforming; Natural gas reacts with steam under very high temperatures/pressures, and in the prescence of a nickel catalyst. This process releases hydrogen and carbon monoxide.
2. Gasification; This involves using coal or biomass, reacting it with steam and/or oxygen at very high temperatures, but without combustion. It produces carbon monoxide and hydrogen gas. It is commonly used with a biomass source, which has taken in CO2 during growth and so isn’t considered a fossil fuel.
3. Pyrolysis; This involves heating biomass in the absence of oxygen, which breaks down the molecules. It produces hydrogen gas and carbon monoxide.
4. Electrolysis; This involves the splitting of water molecules into hydrogen and oxygen using electricity and an electrolyser device (fuel cell).

Question 5

What are 3 advantages and disadvantages of hydrogen fuel

Answer 5

1. Renewable energy source and huge in supply
2. Practically a clean energy source
3. More efficient
4. Very expensive
5. Very difficult to move around
6. Lacks a smell to leaks are difficult to notice making it unsafe

Question 6

What is the source of nucleur energy

Answer 6

Uranium 235

Question 7

How is nucleur energy produced

Answer 7

Fission is the main process used for generating nuclear energy, and involves splitting of atoms to release energy which can then be harnessed.
When 235U undergoes fission, the nucleus splits into two smaller nuclei plus a few neutrons, releasing heat energy and gamma radiation. The neutrons hit other uranium nuclei and cause them to split, causing a chain reaction. The chain reaction must be controlled in a nuclear reactor to stop it going too fast. the energy released through fission is used to heat water and generate steam, which turns turbines and generates electrical power

Question 8

Name 3 advantages and disadvantages of nucleur energy

Answer 8

1. Costs about the same as coal
2. Produces huge amounts of energy for little fuel
3. Cleaner energy; does not contribute to greenhouse effect
4. Potentially dangerous; chernobyl
5. Radioactive waste products will stay radioactive for thousands of years
6. Raw material; Uranium is naturally unstable