Fossil Fuels

partial decomposition of dead organic matter under anaerobic conditions beneath layers of sediments that were deposited on the Earth’s surface or seabed

300-360m years ago

Since the 1700s They have particular features that made them ideal for use

• easy to store • high energy density so they can power high energy intensity activities e.g. smelting steel and powering steam engines (high energy density means it is relatively efficient to transport: a given volume or mass contains a lot of energy) • often found in very abundant local deposits

coal gasification coal liquefaction

burning coal underground (that is too deep to be mined) under controlled conditions to produce syngas: a mixture of fuel gases including hydrogen, carbon monoxide and methane

it is converted into transportation fuels like gasoline and diesel through the Fischer-Tropsch process e.g. the Sasol chemical company of S. Africa to make gasoline from coal and nat gas OR the hydrogen obtained from gasification can be used for powering a hydrogen economy, making ammonia or upgrading ff

• the coal is mixed with oxygen and steam whilst being heating and pressurised • during the reaction, oxygen and water molecules oxidise the coal into carbon monoxide while also releasing hydrogen gas (coal) + O2 + H2O = H2 + CO • this process has been conducted in both underground coal mines and in coal refineries

• minimal surface destruction • no open cut mining • minimal infrastructure • increased health and safety for personnel • high energy density • economical

the conversion of coal to liquid hydrocarbons, which have applications that solid coal cannot perform such as liquid vehicle fuels • If gasoline is wanted, the syngas is collected after the gasification process and routed into a Fischer-Tropsch reaction • if hydrogen is wanted, the syngas is fed into the water gas shift reaction where more hydrogen is liberated CO + H2O = CO2 + H2 • can be converted to liquids directly using solvents or indirectly using gasification then chemical changes to convert gaseous hydrocarbons to liquid hydrocarbons

• high prices of oil and nat gas The Synthetic Fuels Corporation was a U.S. gov-funded corporation established in 1980 to create a market for alternatives to imported fossil fuels (e.g. gasification) but was discontinued in 1985 • in the past, coal was converted to make coal gas, which was piped to customers to burn for illumination, heating and cooking. At present, the safer nat gas is used instead

• accesses coal seams too deep to be mined: it can be burnt underground in controlled conditions to produce the mix of goal gases

Oil recovery Directional drilling Subsea production wells ROVs and AUVs Fracking Tar sands and oil shales

Primary Secondary Tertiary

• well-established method that uses the natural pressure of water below the oil, or gas that is present above the oil, or dissolved in it • the pressure forces the oil up the production well to the surface • a pump jack fitted at ground level on the production well may be used to increase the flow rate

• involves pumping water or nat gas down an injection well to maintain the pressure and the flow of the oil • some CCS schemes pump the recovered CO2 underground to increase oil recovery in addition to storing the CO2

Techniques reducing the viscosity of the oil (also called Enhanced Oil Recovery (EOR)) THERMAL RECOVERY - steam may be pumped down to heat the oil. This steam may be generated by burning fuel, or from solar heating schemes, using parabolic concentrators. Reduces viscosity and allows easy flow to the surface - viscosity may also be reduced by controlled underground combustion which heats it up - most prevalent EOR in the USA GAS INJECTION - nat gas, nitrogen or CO2 (increasingly most popular) are injected into the res to mix with the oil, making it more viscous, whilst simultaneously pushing the oil to the surface (similar to secondary oil recovery) CHEMICAL INJECTION - detergents or solvents reduce the surface tension of the oil and make it flow more easily, freeing trapped oil - least common EOR method • bacteria are used to partially digest heavy oil and produce lighter oils that flow more easily. The bacteria also produce CO2 which helps to maintain the pressure and the flow of oil

a) 20% b) increases it to 40% c) increases it to 60%

allowing wells to be drilled that are not vertical to better reach and produce oil/gas reserves

• many wells can be drilled from a single platform/vertical well bore, minimising env impact • it is possible to drill underneath locations where drilling rigs could not be placed e.g. urban areas • drilling can follow weaker or softer rock strata to make drilling quicker and can target multiple small reservoirs up to 10km from the well head (this significantly increases total recovery rates)

• the tungsten carbide teeth of the drill bit grind the rock into fragments • the hole in the drill bit delivers a fine mud suspension that lubricates the drill • improved drilling sensors and global positioning tech mean the drilling tech is way better. The angle of a drill bit is controlled with intense accuracy through real-time tech, solving industry challenges like increasing efficiency and decreasing costs

wells located on the seabed and have no platform at the sea surface e.g. The Maria Subsea Field, Norway • they allow operations in water up to 2000m deep, although new developments will allow operations at greater depths

a) Remotely Operated Vehicles b) Autonomous Unmanned Vehicles Used to carry out seabed surveys and to inspect underwater production equipment and pipelines

Large volumes of crude oil/nat gas trapped in the pore spaces of shale rocks that have low permeability