future of energy supplies- fossil fuels

Question 1

how are fossil fuels produced

Answer 1

partial decomposition of dead organic matter under anaerobic conditions

Question 2

outline advantage features of fossil fuels which increased their usefulness

Answer 2

1) easy to store
2) high energy density
3) often found in abundant local deposits

Question 3

how does fossil fuels having a high energy density increase their usefulness

Answer 3

1) high temps produced when burnt enabling the smelting of metal ores
2) buring produces high pressure steam which can be used to produce electricity
3) small mass of fuel produces large amount of energy - ease of transport and storage

Question 4

outline disadvantage features of fossil fuels

Answer 4

finite resource- it is non-renewable so will become depleted
- effects industries which grew around the resources as once the materials exhausted the industry can only survive if materials are transported from elsewhere

Question 5

outline why a lot of fossil fuels are considered as resources and not as reserved

Answer 5

1) oil and coal may be too deep to exploit or are too small
2) a lot of natural gas is trapped in impermeable shale deposits
3) unacceptable pollution or habitat damage is too great
4) extraction may cause local earth tremors

Question 6

outline how coal is currently extracted

Answer 6

1) deep mining
- labor-intensive
- relatively expensive
2) open cast mining
- mechanized
- more economically viable
- can only access surface deposits

Question 7

outline the environmental impacts of mining coal

Answer 7

1) habitat loss
2) turbid drainage water
3) spoil heaps
4) acid mine drainage

Question 8

outline environmental impacts of oil extraction and transport

Answer 8

1) oil pollution
2) marine seismic surveys
3) habitat damage from pipeline construction

Question 9

outline the environmental impact of the combustion of fossil fuels

Answer 9

1) atmospheric pollution

2) ash disposal

Question 10

outline the new technologies in extracting coal

Answer 10

1) coal gasification - coal too deep to mine is burnt undergorund in controlled conditions to produce a mixture of fuel gases including hydrogen, methane, and carbon monoxide
2) coal liquefaction- the conversion of coal into liquid hydrocarbons using solvents that have applications solid coal cant do such as liquid vehicle fuels

Question 11

outline new technologies in types of oil recovery

Answer 11

• primary oil recovery - the use of natural water and gas pressures below or dissolved in the oil to push it up towards the surface allowing 20% extraction
• secondary oil recovery - the pumping of water of gas down an injection wells to maintain pressure and flow of oil increasing recovery to 40%
• tertiary oil recovery - use of techniques to reduce the viscosity of oil such as use of detergents to reduce surface tension to make flow easier

Question 12

outline fracking

Answer 12

a new oil recovery method

• recovery large volumes of oil trapped in pores spaces of shale rock by using high pressure to open fissures allowing oil or gas to flow towards a recovery well
• water can be pumped into these fissures to increase recovery

Question 13

what are some concerns over fracking

Answer 13

1) natural gas may enter aquifer water
2) chemical injected may enter aquifer water
3) toxic metals in the rock may become mobile
4) earthquakes

Question 14

list new techniques in the recovery of natural gas

Answer 14

1) enhanced gas recovery
2) fracking
3) methane hydrates
4) carbon capture and storage

Question 15

what is enhanced gas recovery

Answer 15

increases gas recovery rates using techniques such as injection of co2 or nitrogen around the edge of a gas field to maintain pressure and gas flow

Question 16

what are the type of extraction methods for methane hydrates

Answer 16

1) water heating- hot water is pumped into the sediments which melt the hydrate crystals releasing the gas
2) depressurisation- drilling into sediments causing the pressure to drop and methane to gradually dissociate from the crystals
3) co2 injection- at high pressure co2 can also form bonds with the crystals which are stronger than the methane bonds, its injection causes methane to be displaced and collected, it can also be apart of the carbon capture and storage scheme