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Earth and Environmental Science

Home > Earth and Environmental Science > Options > Organic Geology - A Non-renewable Resource > Organic geology: 1. Earth materials formed from organic material

9.6 Option — Organic geology: 1. Earth materials formed from organic material

Syllabus reference (October 2002 version)
1. The properties of economically important Earth materials formed from organic material	Students learn to: distinguish between the nature of renewable and non-renewable resources assess estimates of known reserves of non-renewable resources in the light of technological innovation define fossil fuels as ‘useful organic-matter-derived Earth materials’ describe the changes in coal with increasing rank in terms of: physical properties composition grade energy yield describe properties of liquid petroleum in terms of composition and energy yield describe properties of gaseous fossil fuels in terms of composition and compare the energy yields of coal-derived gas and petroleum-derived gas	Students: process information from secondary sources to classify renewable and non-renewable resources commonly in use identify data sources, gather information and perform a first-hand investigation to identify and classify a variety of fossil fuels commonly used and compare their properties and uses

Extract from Earth and Environmental Science Stage 6 Syllabus (Amended October 2002). © Board of Studies, NSW.

[Edit 14 Oct 04]

Prior learning: Science Stages 4–5 syllabus: Outcomes 4.11 (content 4.11.1 a, b, and c), Outcome 5.11 (content 5. 11.1 a and b).

distinguish between the nature of renewable and non-renewable resources

• A renewable resource is one that is replaced, or can be replaced, at a rate greater than or equal to the rate at which it is comsumed.
  
  
• Some common renewable resources are -
  • water - it is recycled by nature.
  • wood - produced through photosynthesis in a relatively “short” time.
  • wind power - can sometimes be harnessed depending on local conditions
  • solar energy - available in most locations during daytime hours.
    
    
    
• A non-renewable resource is a resource that is used by humans at a rate faster than its rate of formation.
  
  
• Some common non-renewable resources are:
  • coal, oil and natural gas - developed by geological processes over millions of years
  • most minerals - developed by geological processes over thousands and millions of years.

process information from secondary sources to classify renewable and non-renewable resources commonly in use

• In this syllabus point, collect a list of resources and use the definitions in the syllabus point above to classify them as renewable and non-renewable. The following sites provide structured activities to dicsuss and classify renewable and non-renewable resources.
  
  Natural Resources A web quest hosted by Kent State University, Ohio, USA.
  Activity 1.4: Paper, Plastic, or Bring Your Own? [Field of Genes (FOG), Making Sense of Biotechnology in Agriculture, a site developed through a partnership involving National 4-H Council, Monsanto The Agricultural Group, and Pioneer hi-Bred International].
  
  
• Process your gathered list into two lists or a two column table to classify the resources as renewable or non-renewable.

define fossil fuels as ‘useful organic-matter-derived Earth materials’

Fossil fuels are useful organic-matter-derived Earth materials.

assess estimates of known reserves of non-renewable resources in the light of technological innovation

Estimates of the longevity of fossil fuel reserves vary greatly.

The Coming Global Oil Crisis web site has some information on oil production in the US.

Another web site The Oil Reserve Fallacy site is much more optimistic about oil reserves.

The following is quoted from the Rainforest Action Network, USA. It is an extract from an article that has the web site listed below.

“Over 800 billion barrels of oil have been burned since the search for oil began in 1859. The world is continuing to increase its consumption of oil and gas. As the consumption of fossil fuels has increased, the oil industry has continued to look for more. Over the last 25 years, known reserves of oil have increased by almost 70 percent, to the point where if all new exploration for oil and gas were to stop tomorrow, the wells would not run dry for at least the next 47 years. To understand what this means, one must understand how oil and gas reserves are calculated. The amount of hydrocarbons available is not simply a function of geology, but also of economics, technology, and politics. Identified Reserves refer to oil and gas that have been discovered and remain in the ground, but could be extracted economically using today's technology.

Additions to reserves can take place as technological advances allow access to previously uneconomical oil, as has happened over the last decade with deep offshore technology, horizontal drilling, and the increased use of advanced seismic mapping technology.

The price of oil or gas also has a significant impact on reserves estimates-as price goes up, the higher cost of extraction from smaller, more marginal finds become more economically viable, and those fields are added to reserve estimates. There is general consensus that current conventional reserves of oil are in the area of 1,000 billion barrels, while for gas there are approximately 800 billion barrels of oil equivalent.

The US Geological Survey estimates that approximately 530 billion barrels more of oil remain to be found. The real debate here centres not on the ultimate amount of oil that will be found and extracted, but rather on when the world will pass its peak of global production. Once that happens, oil will become progressively more expensive to extract, and thus, more expensive to all of us. Scarcity advocates argue that global production will peak, and prices will begin a long rise, within the next 10 years.”

The case against new fossil fuel exploration The Rainforest Action Network, USA.

Assess these and other estimates to come up with what you think is a reasonable estimate.

identify data sources, gather information and perform a first-hand investigation to identify and classify a variety of fossil fuels commonly used and compare their properties and uses

• You could look in science text books such as Perspectives of the Earth by Clark and Cook, and Earth and Environmental Science, The HSC Course by Hubble, Huxley and Imlay-Gillespie or encyclopedias or do a brainstorm in the class room to identify a variety of fossil fuels commonly used. Some information is available on the Internet.
  
  
• When you have compiled a list of possible fossil fuels, choose several to give you a variety so you will be able to compare their properties and uses.
  
  
• Classify them into chosen categories. Some categories could be:
  • Type of fossil fuel eg, solid, liquid or gas. Other classifications could be low polluting and high polluting or high energy yielding and lower energy yielding.
  • Properties
  • Uses
    
    
• Use a table like the one below to compare the different types and their properties and uses.

Fossil fuel	Properties	Uses
Solid, eg Coal
liquid eg Oil	Can be refined to produce many fuels and plastics. Fuels are burnt as an energy source.	Fuels such as petrol and diesel are used for transport, avgas for planes. Plastics are used very widely from prosthetics to chairs to containers.

describe the changes in coal with increasing rank in terms of:

• physical properties
• composition
• grade
• energy yield

• As coals increase in rank, their relative density increases, the fixed carbon content increases, whereas the abundance of moisture (water on and within the coal particles) and volatile components (components forming organic and inorganic gases) decrease.
  
  
• This process of chemical and physical change during rank advance transforms the low rank coals (peat and brown coal) into soft brown coals (bituminous coal) and with increasing rank into harder black coal (anthracite).
  
  
• Grade does not directly relate to rank, however it quantifies the coal in terms of the percentage of mineral matter and salt content. High grade coals are more pure, with less minerals.
  
  
• Coking grade coals are usually higher rank coals.
  
  
• The specific energy (calorific) is a measure of the amount of heat energy available per unit mass (energy yield).
  
  
• The higher the rank or grade of coal, the greater the energy yield per unit mass of coal.

describe properties of liquid petroleum in terms of composition and energy yield

Liquid petroleum such as petrol, kerosene and oil contain a complex mixture of hydrocarbons ranging from pentane to nonadecane. Find out what happens to the properties as the number of carbon atoms in the compounds present increases.

Some compounds present in fuels

1. Petrol
   Hexane C₆H₁₄ ; Boiling point = +69^oC
   Nonane C₉H₂₀ ; Melting point = -51^oC
   Hendecane C₁₁H₂₄ ; Melting point = -26^oC
   
   
2. Oils
   Octadecane C₁₈H₃₈ ; Melting point = +28^oC
   Nonadecane C₁₉H₄₀ ; Melting point = +32^oC

Now find out what effect the changing melting point has on energy yield.

describe properties of gaseous fossil fuels in terms of composition and compare the energy yields of coal-derived gas and petroleum-derived gas

• Natural gas is a mixture of methane (75-90 %), ethane (5-10 %), propane and butane (3-6 %) and smaller amounts of higher alkanes with some nitrogen or carbon dioxide gases (refer to the above figure).
  
  
• Natural gas produces about 37 kilojoules of energy per cubic metre of natural gas burnt but LPG (liquified petroleum gas) produces about 105 kilojoules per cubic metre burnt. Syngas is produced from coal and is a mixture of carbon monoxide and hydrogen but it has a very low energy value at about 9 kJ of energy per cubic metre of gas burnt. Synthetic natural gas is also produced from coal. It is mostly methane and produces about 30 kJ of energy per cubic metre burnt.