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World energy consumption (1965-2005)
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Fossil fuels
• The three most important fossil fuels are:– Crude oil– Coal– Natural Gas
• Combustion of fossil fuels are the major sources of energy in many countries, especially for production of electricity and transportation.
Four-stroke cycle internal combustion engine
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Use of Fossil Fuels in transportation
• Transportation is one the major user of fossil fuels beside electricity production.
Problem with fossil fuels
• Combustion of fossil fuels is the main source of a number of air pollutants. These include carbon dioxide which is a major Greenhouse Gases (GHG) contributing to global warming.
• As fossil fuels take millions of years to form, their storage in the crust is limited.
Limited reserve of Fossil Fuels
• At the current rate of consumption, it is estimated that the current reserves will run out in:– Oil 32 years– Gas 52 years– Coal 252 years (Source: EIA, USA)
Historical Contributions: Major Data Constraints
Cumulative CO2 Emissions, Comparison of Different Time Periods
Map of global solar energy resources. The colors show the average available solar energy on the surface during 1991 to 1993. The scale is in watts per square meter. For comparison, the dark disks represent the land area required to supply the primary energy demand in the year 2010, using currently available technology.
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Solar oven for cooking
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Wind energy
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Geothermal energy
Bjarnarflag Geothermal Station in northeast IcelandSteam from underground are used to drive turbine to generate electricity. (Source: Wikipedia)
Potential of Renewable energy
Available renewable energy. The volume of the cubes represent the amount of available wind and solar energy. The small red cube shows the proportional global energy consumption. Values are in TW =1012 Watt. The amount of available renewable energy dwarfs the global consumption
Nuclear Energy• The most common fuel for commercial nuclear energy
plants is Uranium.• Uranium is a common element, occurring almost
everywhere on land and in the oceans. It is about as common as tin, and 500 times more common than gold.
• Different types of nuclear fission reactors use different type of nuclear fuels:– Light water reactors: uranium-235– Fast breeder reactors: uranium-238
• Reserve of nuclear fuels in nature can last from 50years to hundreds of year depend of fuel type and reactors.
Nuclear Energy and the Environment
• Past events like Chernobyl accident and the Three Miles Island accident cause general public to worry about safety of nuclear, even when scientific community generally agree that probabilities of such accidents to be very small.
• Disposal of radioactive wastes with long half-life produced by nuclear power station remain to raise environmental concerns.
Uncontrolled nuclear fission in nuclear explosion resulting in the release of the vast amount of energy and radiation (Source: United States Department of Energy)
Nuclear Fuel Cycle
• Uranium is mined, enriched and manufactured to nuclear fuel (1)
• The nuclear fuel is delivered to a nuclear power plant. After usage in the power plant the spent fuel is delivered to a reprocessing plant (2) or to final repository (3) for permanent storage in a safe place, such as inside rock.
• In reprocessing 95% of spent fuel can be recycled to be returned to usage in a power plant (4).
A nuclear power plant with water vapour rising from cooling towers
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State of commercial nuclear plant
Diversified choice: Some countries are building new nuclear power plants, whileSome countries are decommissioning present plants.