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Energy - Fossil fuels - Coggle Diagram
Energy - Fossil fuels
Features of fossil fuels
Energy density: high energy density
- HIgh temps produced by coal can be used to melt metals
- Can produce high pressure steam
- Allows a small mass of fuel to do a lot of work
- 75t of avian fuel can carry a massive plane, if we did not use these fossil fuels then it would likely be impossible to do this
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Available resources: the total quantity of fossil fuels is very large however it is very hard to actually get to these resources
Level of technological development: Some industrial societies have developed technologies to exploit them are well developed.
Economic issues: economic activity and international trade can drive countries to make decisions based on the cheapest options.
When cheap natural gas became available in the UK it contributed ti the closure of the deep coal mines even though there was a substantial amount of coal that could still be extracted
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New fuel technologies
Coal
Coal gasification
Coal that is too deep can be burnt underground under controlled conditions to produce a mixture of fuel gases including hydrogen
Coal liquefaction:
This involves the conversion of coal to liquid hydrocarbons which has new applications
This coal can be liquefied using solvents or indirectly by gasification
Oil
Fracking
Large volumes of crude oil and natural gas are trapped in pore spaces of shale rocks that have low permeability. These are called tight gas or tight oil
Hydraulic fracturing uses high pressure to open fissures in shale rock to allow oil/gas to flow towards a recovery well.
Concerns over fracking
- Natural gas may enter the aquifers
- Chemcals injected underground may enter aquifers which could lead to damage.
- Toxic metals that are usually present may become mobile
Directional drilling
Allows oil to be drilled in directions that are not vertical
- Many wells can be drilled from the same platform.
- Is possible to drill underneath locations where drilling rigs could not be placed
Tertiary oil recovery
These include techniques which reduce the viscosity of the oil. This is also called enhanced oil recovery (EOR)
- Steam may be pumped down to heat the oil
- Underground combustion can be used to reduce the viscosity
- Detergents or solvents reduce the surface tension of the ol and make it flow more easily.
Subsea production wells
Subsea production wells are located on the seabed and have no platform at the sea surface.
They allow operations in water up to 2km deep.
Secondary oil recovery
Pumping water down an injection well to maintain the pressure and flow of the oil.
CCS schemes store the recovered CO2 underground to increase oil recovery.
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Primary oil recovery
Uses the natural pressure of water below the oil, the pressure forces up the oil up to the production well.
Natural gas:
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Enhanced gas recovery
EGR increases the gas recovery rates using techniques such as the injection of CO2 or nitrogen around the edge of the gas field to maintain pressure and gas flow
Methane hydrate
Solid ice like crystalline solid found in locations at low temperatures or under high pressures
Methane hydrate is not exploited commercially now but could yield more than conventional sources.
Extraction methods:
- Water heating
- depressurization: this is the process of drilling into the sediments which causes the pressure to drop
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