Fossil Fuels: what are they, how are they formed and used?

Fossil Fuels

What are fossil fuels?
How are fossil fuels formed?
History of fossil fuels.
Why do we use fossil fuels?
Advantages of fossil fuels.
How do fossil fuels work?
What are fossil fuel reserves?
Why should we be conservative in our use of fossil fuels?
What can be done to improve the way we use fossil fuels?

What are fossil fuels?

Coaloil and gas are called ‘fossil fuels’ because they have been formed from the fossilized remains of dead prehistoric plants and animals.
All three were formed many hundreds of millions of years ago before the time of the dinosaurs. The age they were formed is called the Carboniferous Period. ‘Carboniferous’ gets its name from carbon, the basic element in coal and other fossil fuels.

How are fossil fuels formed?

Fossil Fuels - Carboniferous Forest

Carboniferous Forest

The Carboniferous Period occurred from about 360 to 286 million years ago. At the time, the land was covered with swamps filled with huge trees, ferns and other large leafy plants, similar to the picture below.

As the trees and plants died, they sank to the bottom of the swamps of oceans. They formed layers of a spongy material called peat. Over many hundreds of years, the peat was covered by sand and clay and other minerals, which turned into a type of rock called sedimentary.

More and more rock piled on top of more rock, and it weighed more and more. It began to press down on the peat. The peat was squeezed and squeezed until the water came out of it and eventually, over millions of years, it turned into coal.

Unlike coal, oil and gas were formed in seas and oceans instead of swamps. These bodies of water abounded with organisms such as plankton. When these organisms died they settled on the bottom in large quantities. Over a long period of time, this organic matter, mixed with mud, got buried under heavy layers of sediment. The resulting high levels of heat and pressure caused the organic matter to chemically alter. First into a waxy material known as kerogen, which is found in oil shales, and then with more heat into liquid petroleum and, with even more heat, into natural gas.

History of fossil fuels:

The use of coal as a fuel predates recorded history. Coal was used to run furnaces for the melting of metal ore. Commercial exploitation of petroleum, largely as a replacement for oils from animal sources (notably whale oil), for use in oil lamps began in the 19th century. Prior to the latter half of the 18th century, windmills and watermills provided the energy needed for industry such as milling flour, sawing wood, or pumping water, and burning wood or peat provided domestic heat.

Fossil Fuels SteamengineThe wide scale use of fossil fuels, coal at first and petroleum later, to fire steam engines enabled the Industrial Revolution. At the same time, gas lights using natural gas or coal gas were coming into wide use. The invention of the internal combustion engine and its use in automobiles and trucks greatly increased the demand for gasoline and diesel oil, both made from fossil fuels. Other forms of transportation, railways and aircraft, also required fossil fuels. The other major use for fossil fuels is in generating electricity and as feedstock for the petrochemical industry. Tar, a leftover of petroleum extraction, is used in construction of roads.

Why do we use fossil fuels?

Fossil fuels are of great importance because they can be burnt, producing significant amounts of energy. We all know that we need fossil fuels to generate electricity and as fuel for cars, trains and airplanes. We also use it to heat our homes and to cook our food. Tar is used in road construction. Petroleum is also used in the production of plastics, textile fibers and synthetic rubber, and it is widely used in the pharmaceutical industry. Petrochemicals have had a dramatic impact on our food, clothing, shelter and leisure. Some synthetics, tailored for particular uses, actually perform better than products made by nature because of their unique properties.

At present coal provides around 31% of our energy, and oil provides 32%. Natural gas provides around 24% of the world’s consumption of energy. This amounts to an 87% share for fossil fuels in primary energy consumption in the world. Non-fossil sources in 2012 include hydroelectric 6.5%, nuclear 5%, and others (geothermal, solar, tide, wind, wood, waste) amounting to 1.5 percent. According to BP’s Statistical Review of World Energy for 2011 global energy consumption growth was 5.6%, the highest rate since 1973.

Fossil fuels power plantAdvantages of fossil fuels:

A fossil-fuelled power station can be built almost anywhere, so long as you can get large quantities of fuel to it. This is not a problem since transporting oil and gas to the power stations through pipes is easy. Gas power stations are very efficient and produce comparatively little pollution while using coal allows us to generate very large amounts of electricity fairly cheaply.

How do fossil fuels work?

Coal is crushed to a fine dust and burnt, while oil and gas can be burnt directly.

How fossil fuels work
Fossil fuels Power station cooling towersThe steam that has passed through the power station’s turbines has to be cooled, to condense it back into water before it can be pumped round again. This is what happens in the huge ‘cooling towers’ seen at power stations. Some power stations are built on the coast, so they can use sea water to cool the steam instead. However, this warms the sea and can affect the environment, although the fish seem to like it.

What are fossil fuel reserves?

Fossil fuel reserve is the amount of fossil fuel still in the ground which can be extracted in such a way that companies can make a profit from it. Over time we have already extracted a lot of coal, oil and gas. Other fossil fuels are being investigated, such as bituminous sands and oil shale.

Fossil Fuels - Oil wellThe difficulty is that they need expensive processing before we can use them; however Canada has large reserves of ‘tar sands’ , which makes it economic for them to produce a great deal of energy this way.

As far as we know, there is still a lot of oil in the ground. But although oil wells are easy to tap when they’re almost full, it’s much more difficult to get the oil up later on when there’s less oil down there. That’s one reason why we’re increasingly looking at these other fossil fuels.

World coal and gas proven reserve estimates vary widely from 118 to 417 years for coal, and from 60 to 167 years for natural gas. Most experts seems to agree that proven oil reserves will only last another 43 years, but some seem confident there may be enough oil for another 100 years once we develop new extraction techniques.

‘Proven reserves’ refer to reservoirs of oil, coal seams, and natural gas deposits that companies are sure they can make a profit from, if they could bring them up using current extraction technologies and if today’s production of oil wouldn’t change. In fact production does change. In the last 45 years the annual growth rate of oil production has swayed between 10% and -5.8%.

Therefore there are a few problems with proven reserves calculations :
These numbers are based on proved reserve estimates assuming that these fuels could be produced at a constant level for that number of years and that all of the proved reserves could be recovered.

Fossil Fuels Hubbert-Curve

Bell Curve

In reality, the production curve is much more akin to a bell curve. At some point in time, the production of each resource within an area, country, or globally will reach a maximum value, after which, the production will decline until it reaches a point where is no longer economically feasible or physically possible to produce. Therefore the actual reserves may be much smaller than estimated.

On the downside:

  • These numbers are based on current energy use assuming that energy use will remain at the same level. In reality energy use has steadily increased over the past years and continues to increase. Therefore actual reserves will last fewer years than estimated.

On the upside:

  1. Since these numbers are based on proved reserve estimates they may last a whole lot longer if we manage to develop the necessary technology to tap into hitherto unknown reserves.
  2. Note also that proved reserve estimates do not include strategic reserves, which (globally) amount to 4.1 billion more barrels.

Fossil fuels are not a renewable energy resource because they take millions of years to form, and reserves are being depleted much faster than new ones are being made. Once we’ve burnt them all, there isn’t any more, and our consumption of fossil fuels has nearly doubled every 20 years since 1900. We may be able to develop the necessary technology to replace fossil fuels by renewable energy but it will be very hard to replace oil for the production of plastics and for the pharmaceutical industry. Therefore it might be wise to already stop using oil for the production of fuel and electricity right now in order to save it for the production of these other products. The production and use of fossil fuels raise environmental concerns. A global movement toward the generation of renewable energy is therefore under way to help meet increased energy needs.

Why should we be conservative in our use of fossil fuels?

Fossli fuels coal-mineMining coal can be difficult and dangerous as can drilling for petroleum and gas, but the main drawback of fossil fuels is pollution.

For example: the electricity sector is the largest uncontrolled industrial source of mercury emissions in Canada. In addition, the sector has significant impacts on water and habitat and species. In particular, hydro dams and transmission lines have significant effects on water and biodiversity. Burning fossil fuels generates sulfuric, carbonic, and nitric acids, which contribute to smog, the formation of fine particulate matter and which fall to Earth as acid rain. These acids dissolve the calcium carbonate in monuments, sculptures and buildings made from marble and limestone. They also change the acidity in the ground which has an adverse effect on the natural environment.

Although it is possible to clean up these acids before releasing the waste gases into the atmosphere, this method uses a lot of limestone. Fortunately it also produces gypsum for the building industry as a by-product.

Offshore oil drilling poses a hazard to aquatic organisms as does the transportation of oil with tanker ships, while leaking pipelines are a hazard for the natural environment in general. Oil refineries also have negative environmental impacts, including air and water pollution.

Coal seems to be the worst fossil fuel in terms of pollution:

  1. Fossil fuels coal-mining-strip-miningMountaintop removal and strip mining destroy large areas of the landscape, causing negative environmental impacts.
  2. Coal fired power plants need huge amounts of fuel, which means train-loads of coal almost constantly which requires the combustion of additional fossil fuels.
  3. In order to cope with changing demands for power, the station needs reserves. This means covering a large area of country next to the power station with piles of coal.
  4. Fossil fuels contain radioactive materials, mainly uranium and thorium, which are released into the atmosphere. In 2000, about 12,000 tons of thorium and 5,000 tons of uranium were released worldwide from burning coal. However, this radioactivity from coal burning is minuscule at each source and has not shown to have any adverse effect on human physiology.
  5. Burning coal also generates large amounts of bottom ash and fly ash. Fortunately these materials are used in a wide variety of applications. For example, about 43% of U.S. produced fly ash is recycled and used among others, as a supplement in concrete production. Bottom ash may be used as an aggregate in road construction and concrete.
  6. And last but not least: Burning coal produces more carbon dioxide than burning oil or gas.

Carbon dioxide (CO2)Fossil fuels - Limit Carbon Dioxide Emissions is one of the greenhouse gases that contribute to global warming. The burning of fossil fuels produces billions of tons of CO2 per year. It is estimated that natural processes can only absorb about half of the CO2 we produce globally every year, so there is a net increase of nearly 11 billion tons of atmospheric carbon dioxide per year. Scientists know with virtual certainty, meaning 99% sure, that:

  1. Human activities are changing the composition of Earth’s atmosphere. Increasing levels of greenhouse gases like carbon dioxide (CO2) in the atmosphere since pre-industrial times are well-documented and understood.
  2. The atmospheric buildup of CO2 and other greenhouse gases is largely the result of human activities such as the burning of fossil fuels.
  3. An “unequivocal” warming trend of about 1.0 to 1.7°F occurred from 1906-2005. Warming occurred in both the Northern and Southern Hemispheres, and over the oceans (IPCC, 2007).
  4. The major greenhouse gases emitted by human activities remain in the atmosphere for periods ranging from decades to centuries. It is therefore virtually certain that atmospheric concentrations of greenhouse gases will continue to rise over the next few decades.
  5. Increasing greenhouse gas concentrations tend to warm the planet.

It is therefore very likely, greater than 90% chance, that rising levels of greenhouse gases in the atmosphere are contributing to climate change. In the coming decades, scientists anticipate that as atmospheric concentrations of greenhouse gases continue to rise, average global temperatures and sea levels will continue to rise as a result and precipitation patterns will change.

Many climate scientists predict that this will cause major adverse effects such as a large increase in floods, typhoons, cyclones, desertification and other natural disasters. More research on the subject is being done.

Although CO2 is also released into the air through natural events such as volcanic eruptions, greenhouse gas emissions from volcanoes comprise less than one percent of those generated by today’s human endeavors. According to the Energy Information Administration in its December 2009 report ‘Emissions of Greenhouse Gases’ in the United States, 81.3 percent of greenhouse gas emissions in the United States in 2008 came from energy-related carbon dioxide.

Fossil fuels - CO2-tonsGlobal fossil carbon emission by fuel type, 1800-2007. Note: Carbon only represents 27% of the mass of CO2 Fossil fuels CO2-variationCarbon dioxide variations over the last 400,000 years, showing a rise since the industrial revolution.

What can be done to improve the way we use fossil fuels?

Environmental regulations can be implemented by various governments to limit greenhouse gas and other emissions, such as command-and-control (which mandates the amount of pollution or the technology used). An example of such regulation in the USA is the implementation of policies to reduce airborne mercury emissions.

Under regulations issued in 2005, coal-fired power plants will need to reduce their emissions by 70 percent by 2018. Other ways to control emissions are economic incentives, or voluntary programs. In economic terms, pollution from fossil fuels is regarded as a negative externality. Taxation is considered one way cover the cost of pollution. This aims to make fossil fuels more expensive, thereby reducing their use and the amount of pollution associated with them, along with raising the funds necessary to counteract the cost of pollution.


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