5 Fossils Fuels & Nuclear

(7) Clean and affordable energy & (13) Climate Action

Describe the role of fossil fuels within the global carbon cycle 

CO2 in the atmosphere is used for terrestial and aquatic photosynthesis and released into the air due to respiration, decomposition and burning of fossil duels

Explain the geological processes that lead to coal formation.  

Burial pressure, heat and time convert organic matter into coal

Classify coal types: lignite

• 25-35% C

• 4000 - 8000 Btu/lb

• light brown, matte

Classify coal types:sub-bituminious

• 35 - 45% C

• 8300 - 115000 Btu/lb

• grey matte

Classify coal types: bituminious

• 45 - 86% C

• 10500 - 14000 Btu/lb

• dark grey/ black, matte

Classify coal types: anthracite

• 86 - 97% C

• ~15000 Btu/lb

• dark, shiny and hard

Evaluate environmental impacts associated with coal impurities and combustion products. 

• CO and CO2

  • GHG

  • poisonous carbon monoxide

• clay and non-combustibles

  • ash

  • respiration and light coverage

• carbonate minerals

• NH4 → N20, NO, NO2

  • GHG

• H2S and FeS2 → SO2

  • sulphuric acid = acid rain

• trace element A, F, U

  • radioactive

• NaCl

  • corrosion in boiler plants

Explain coal processing methods to form coke 

coke formotion is due to carbonisation → essential for increased mechanical strength, radiactivity and steel industry

• Butiminous coal heated to ~1000°C 

• absence of oxygen removes volatile components

• carbon rich, solid ‘coke’ remains

Explain the pathway from organic matter to oil and gas.  

Diagenesis 

• Small marine organisms die and become ingrained in porous sedimentary rock 

• Occurs at 50°C/ up to 300m 

 

Catagenesis 

• Organisms are converted to hydrocarbons 

• Cracking process where crude oil and naural gas can be exploited 

• Up to 150°C / 1500 atm/ 3.5-5 km 

 

Metagenesis 

• Hydrocarbons crack into carbon rich residuals 

• Below 4 km/ Above 1500 atm/ Above 150°C 

 

What is natural gas

>99% methane (CH4 ), with minor higher hydrocarbons form in both terrestrial and marine environments  

Gas sits on top of oil under impermeable rock 

What is pertroleum

mixture of numerous hydrocarbon compounds, formed in marine environments 

Describe the components of a petroleum system (source, reservoir, seal, trap).  

Source rock -> rock from which hydrocarbons are generated 

 

Reservoirs rock have following properties 

• sandstones 

• Porositty  

  • Oil, brine, hydrocarb, atmo, gas fluid 

• Permeability 

 

Seal 

• Rocks which reduce fluid mighration to subsurface 

  • Evaporitite-halite & mudstone, chalk, crystalline lithologies 

• Properties: 

  • Small pore sire 

  • Ductile 

  • Thick unites 

 

Trap 

• Rock which is above natural gas and oil reservs to stop migration 

Explain the stages of oil recovery (primary, secondary, tertiary).  

Primary (gusher) 

• Uses natural pressure to force oil out 

• 20% recovered 

 

Secondary 

• Inject gas/water to increase pressure 

• 1/3 oil still remains 

 

Tertiary 

• Inject CO2, surfactant or steam

Explain uranium enrichment and fuel fabrication processes  

YELLOW CAKE -> solid concentrated uranium 

• 1 = dynamic treatment 

  • High grade ore 

• 2 = Acid heap leaching 

  • Low grade ore 

Enrichment -> UF6 formation 

• Spun and enriched gas sent through to next cylindedr

• until desire enrichment is obtained 

Describe the geological occurrence and formation of uranium deposits  

In minerals such as zircons and apatite due to large size 

Ore of uranium 

• Uraninite 

• Pitchblende 

 

Deposit types =  

• roll front and  

  • Australia, Kazakhstan 

  • Movement through porous rock -> sandstone 

  • Along curved front 

• Unconformity 

  • Highest U deposits 

  • Meeting a metamorphic and sedimentary basins 

Define and classify radioactive waste (HLW, ILW, LLW, VLLW)  

HLW = high-level waste

• produces radioactivity and waste

• reprocessing fuel, nitric acid solutions

ILW = intermediate-level waste

• high radioactivity byt little heat

• steel, graphite, concrete

LLW = low-level waste

• less than 4GBqs per tonne of alpha activtiy

• or 12GBq per tonne of beta/ gamma activtiy

• plastics, paper and metals, soils, building materials

VLLW = very low-level waste

• controlled or general landfill (volume dependent)