Showing posts with label Fossile Fuel. Show all posts
Showing posts with label Fossile Fuel. Show all posts

Fossile Fuel Problem

By Sara Martins, 11ºZi Escola Secundária de Loulé

To develop its daily activity, mankind uses several sources of energy, with more than 90% of our energy needs being provided by fossil fuels (coal, oil and natural gas), while the remaining 10% are mainly satisfied by nuclear energy and hydroelectric power.

Sources of energy such as wind, the sun, the tides, the waves, geothermal and biomass still have a small expression in world’s energy consumption, though their use is continuously increasing. Our current lifestyle has been made possible thanks to fossil fuels.

The natural gas that heats our homes, the gasoline that makes our vehicles move and the coal that provides much of the electrical power that comes into our houses are, as we know, fossil fuels. Natural reserves of coal, oil and natural gas exist all around the world, but these reserves are not inexhaustible. In fact, the natural processes that allow the formation of fossil fuels take millions of years and we are spending them at a much higher rate than they form. Therefore we can consider fossil fuels as sources of non-renewable energy.


The world’s natural deposits of coal ("BP Statistics", 2004) (click the image too see a larger version)


The world’s natural deposits of crude ("BP Statistics", 2004) (click the image too see a larger version)



The world’s natural deposits of natural gas ("BP Statistics", 2004) (click the image too see a larger version)

The oil crisis in the 70s has caused a 500% raise in the price over a short period of time. It was thought at the time (based on more political than scientific reasoning) that fossil fuels had nearly ended. That made people rush towards the use of renewable energies and made governments increase their research for methods to save fuel. As people realized that there was still much oil they returned to same consumption they had previously.

This way of thinking has reached our days and there are still some people saying that the in the past we have not spent half of the world's oil reserves. Though this is in a certain way true, it is much harder to extract oil from the bottom of the ocean than from earths solid surface and not all the existing oil can be extracted in an economically viable way.

In 1956, Marion King Hubbert, a geologist for Shell developed a mathematical expression able to predict the amount of oil that could be extracted from a well over time is that the quantity of oil that will be produced. It was the basis for construction of a graphs (Hubbert curves) that have been able to follow, with astonishing accuracy, the peaks of exploitation in all geographical areas.
Hubbert assumed that after fossil fuel reserves (oil reserves, coal reserves, and natural gas reserves) are discovered, production at first increases approximately exponentially, as more extraction commences and more efficient facilities are installed. At some point, a peak output is reached, and production begins declining until it approximates an exponential decline.



The Hubbert curve for coal

The Hubbert curve satisfies these constraints. Furthermore, it is symmetrical, with the peak of production reached when half of the fossil fuel that will ultimately be produced has been. It also has a single peak.

Looking at the curves quickly see that the maximum production will be reached within a couple of years. The model of King Hubbert also provides that the maximum coincides with the reduction by half of the reserves of oil initials.

Before 2010, the supply of oil will begin to decline, which means drastic increases in their price, if its demand does not decrease. The ending of the other fossil fuels will also be difficult to solve, with the natural gas expected last little more than oil and coal reserves estimated to last 200 to 300 years.

According to the most optimistic reserve estimates the years left for production of fossil fuels are:
• Oil: 1,277,702/77/365= 45 years
• Gas: 1,239,000/47/365= 72 years
• Coal: 4,786,000/52/365= 252 years

Bibliography
• Nuclear Energy and the Fossil Fuels,M.K. Hubbert, Presented before the Spring Meeting of the Southern District, American Petroleum Institute, Plaza Hotel, San Antonio, Texas, March 7-8-9, 1956

• Hubbert’s Petroleum Production Model: An Evaluation and Implications for World Oil Production Forecasts, Alfred J. Cavallo, Natural Resources Research,Vol. 13,No. 4, December 2004

• Maugeri, L. (2004). Oil: Never Cry Wolf--Why the Petroleum Age Is Far from over. Science 304, 1114-1115

• Global oil & gas depletion: an overview, R.W. Bentley, Energy Policy, 30, 189–205, 2002

• Wikipedia-Fossil fuels (http://en.wikipedia.org/wiki/Fossil_fuel)

• BP Statistics(http://www.bp.com/productlanding.do?categoryId=6848&contentId=7033471)

Fossil Fuel Industry Environmental Impact

by Regina Guerreiro, 12º D
Escola Secundária de Loulé


The combustion of fossil fuels has a daily presence in our lifestyle. Though many people use fossil fuel combustion in their kitchens or for heating, most of the atmospheric pollution generated by fossil fuel combustion is produced in industrial uses, like refineries or thermoelectric production facilities. In the big cities the combustion of gasoline and diesel by cars and other transportation means represents only 40% of the total combustion of fossil fuels.

The combustion gases released are essentially water vapor (H2O), carbon dioxide (CO2) and nitrogen (N2). Of these gases only CO2 emission is hazardous because it is responsible for global warming. Because combustions are seldom complete there are other species like carbon monoxide (CO), nitrogen oxide (NOx), sulfur dioxide (SO2) and lead are often produced. Carbon monoxide is toxic and the nitrogen and sulfur oxides are responsible for acid rains.

Acid rains have made the destruction of many forests in central Europe (Image source: Wikipedia)

The use of fossil fuel combustion is therefore environmentally hazardous and since it is the major source of energy for electricity production and for transportation, one should make a very rational use of electricity and of transportation that implies fossil fuel consumption. Industrial units that use combustion of fossil fuels and automobiles should also use catalytic converters that reduce the emissions of toxic and hazardous components.
Though the emissions of carbon monoxide and nitrogen and sulfur oxides can be reduced by the use of catalysts, carbon dioxide is always emitted. Therefore fossil fuel combustion always leads to global warming.


Global warming is mostly a consequence of CO2 emissions in fossil fuel combustions (Image source: Wikipedia)

Beside the problems associated to the production, use and transportation of crude and its derivatives is related to the atmospheric pollution made by its combustion or transformation or else to accidents. The accidents with tankers aren’t as rare as one should expect. Huge amounts of oil are often released, generating huge pollution marks on the water, that are known as black tides.


Most of the accidents that generated black tides were consequence of accidents with oil tankers. Many of them were the consequence of the aging of the tankers or of inadequate crew training. Black tides are a major concern because they kill fauna and flora in a way that takes several years to be surpassed. The following table presents some examples of major black tides in recent past.