Lesson 8

Read the text: Theory of Combustion of Fossil Fuels.

Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years. The fossil fuels, which contain high percentages of carbon, include coal, petroleum, and natural gas. Fossil fuels range from volatile materials with low carbon: hydrogen ratios like methane, to liquid petroleum to nonvolatile materials composed of almost pure carbon, like anthracite coal. Methane can be found in hydrocarbon fields, alone, associated with oil, or in the form of methane clathrates. It is generally accepted that they formed from the fossilized remains of dead plants by exposure to heat and pressure in the Earth's crust over millions of years. This biogenic theory was first introduced by Georg Agricola in 1556 and later by Mikhail Lomonosov in the 18th century.

Fossil fuels are non-renewable resources because they take millions of years to form, and reserves are being depleted much faster than new ones are being made. 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.

The burning of fossil fuels produces around 21.3 billion tonnes (21.3 gigatonnes) of carbon dioxide (CO₂) per year, but it is estimated that natural processes can only absorb about half of that amount, so there is a net increase of 10.65 billion tonnes of atmospheric carbon dioxide per year (one tonne of atmospheric carbon is equivalent to 3.7 tonnes of carbon dioxide). Carbon dioxide is one of the greenhouse gases that enhances radiative forcing and contributes to global warming, causing the average surface temperature of the Earth to rise in response, which the vast majority of climate scientists agree will cause major adverse effects.

The carbon cycle is a natural process whereby carbon moves in and out of the atmosphere, from the soil, oceans, animals and vegetation. It supports the greenhouse effect, where greenhouse gases have kept the earth comfortably warm since life began.

Fossil fuel is coal, oil and natural gas that was laid down millions of years ago from the carbon of trees, vegetation and even animals. When man digs it up and uses it (by combustion, or burning), this extra carbon is released into the atmosphere, where it is accelerating the greenhouse effect. This accelerated, or enhanced, or runaway greenhouse effect is now causing global warming.

Excess carbon besides CO2 what we give off is put into the atmosphere by fossil fuel burning.

The burning of fossil fuels by human affects the carbon cycle because burning of fossil fuel will release large amounts of carbon into the atmosphere causing the carbon dioxide rate to increase; Which eventually will create greenhouse effect, leading to global warming.
The Carbon Cycle is a natural process by which Carbon Dioxide (a greenhouse gas) is exchanged between the 5 elements which make up the cycle:

1. the biosphere on land;
2. the oceans;
3. the atmosphere;
4. sediments;
5. the earth's interior.

Carbon dioxide along with other greenhouse gasses in the earth's atmosphere allows for the optimal living conditions on earth with regard to the sun's radiation reaching earth. Too little greenhouse gasses would make the world cold, too much would make it too warm.

The burning of fossil fuels ads additional man-made (anthropogenic) carbon dioxide to the cycle, primarily to the earth's atmosphere. Though some elements (primarily oceans and the biosphere) of this natural cycle are able to cope with some of these man-made carbon dioxide emissions, they cannot hold all, even though anthropogenic emissions are relatively minor. As a result of this, more and more man-made emissions are hold in the earth's atmosphere thereby directly affecting the "Greenhouse Effect". As a result, the earth's global temperature is rising.

Дата добавления: 2015-08-03