Energy Resource Project - Fossil Fuels

Energy Resource Project: Fossil Fuels The Need for Energy It is theorised that humans have flourished as a result of our ability to use energy extrasomatically (outside the body). The control of fire and the exploitation of fossil fuels have made it possible for Homo sapiens to release, in a short time, vast amounts of energy that accumulated long before the species appeared. By using extrasomatic energy to modify its environment, the human population effectively expanded its resource base so that for long periods it has exceeded contemporary requirements. The world's present population of over 5.5 billion is sustained and continues to grow through the use of extrasomatic energy.

Sources of Energy All of the energy types available to humans can be associated with one of the following: • Solar activity – Powers wind and the water cycle, is converted into biomass via photosynthesis and is exploited directly for heat and light. • Gravitational pull of the moon and sun – Causes tides. • Nuclear power – Energy released from unstable atoms. • Earth’s Internal Heat – Exploited as geothermal power and directly for warmth.

What are Fossil Fuels? Fossil Fuels include coal, oil, natural gas, synthetic fuels (e.g. gas from coal) and peat. The fossil fuels are primarily a mixture of hydrocarbons (alkanes and alkenes) but also contain impurities such as sulphur compounds. They are formed when the remains of organisms are altered inside the earth’s crust. The energy released from burning fossil fuels originated from solar radiation that has been converted into biomass via photosynthesis (and then stored in ‘fossil’ form).

Exploitation of Fossil Fuels Coal is found at varying depths in the Earth’s crust. When coal seems are near the surface, open cut/cast/pit mining is used. Most coal seams are too deep underground for opencast mining and mining these seams involves underground mining. Crude Oil and Natural Gas are found in the Earth’s crust under sea beds. The oil, along with some natural gas, is trapped by cap (impermeable) rock. This is pierced by a drill and water is pumped into the existing water layer. This forces the oil and natural gas out of the well so that it can be collected by the oil rig

Thomas Sturges-Allard 12.1 AS Level Biology

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The Uses of fossil Fuels Fossil fuel derivatives are used extensively in the chemical industry to produce lubricants, waxes and most importantly plastics. Plastics are made of polymerised hydrocarbons such as ethene which becomes polythene – the plastic used in plastic bags. The primary use of fossil fuels is as a fuel. The alkanes contained within fossil fuels make brilliant fuels as they readily combust. As alkanes vary in length (volatility) then they can be mixed to create combinations ideal for particular purposes

Fossil Fuels as a Energy Resource Alkanes reaction with oxygen exothermically to produce Carbon Dioxide and Water: CnH2n+2 + (1.5+0.5)O2 à n+1H2O + nCO2 This reaction releases a lot of energy as infra-red (heat) and visible light radiation. Alkanes can be gaseous, liquid or solid giving them a wide range of applications. Coal is combusted for heat and for primitive transport. Gas is combusted for cooking heat. Oil is combusted for a variety of transport methods

Problems with Fossil Fuels All fossil fuels when combusted, will produce either carbon dioxide or carbon monoxide. Carbon monoxide is poisonous but is only produced when oxygen is limited (and hence this is avoided). Carbon dioxide is a greenhouse gas. This refers to it’s ability to insulate when present in the atmosphere. Coal and Oil contain a vast array of impurities. During fractional distillation, a lot of impurities are removed from oil but many remain. Combustion in the presence of these impurities creates potentially harmful waste products such as sulphur oxides, nitrogen oxides, toxic metals and particulate matter.

Advantages & Disadvantages of Fossil Fuels Advantages • Relatively cheap at the moment • Technology required is simple and low-cost • Extremely versatile due to variety in composition, chain length and state • Continuing advances in technology are increasing efficiency Disadvantages • Non renewable – use exceeds creation • Contributes to enhanced greenhouse effect/global warming (via Carbon Dioxide) • Contributes to acid rain (via Sulphur Dioxide) • Can be volatile – difficult to store • Has toxic bi-products

Thomas Sturges-Allard 12.1 AS Level Biology

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