World energy sources Sources of energy include Coal Oil Natural gas Uranium Solar Wind Wave Tidal Biofuel Hydroelectric Geothermal
Fossil Fuels Coal, Oil and Natural Gas are fossil fuels. These are formed from the fossilized remains of plants and tiny organisms buried 600 million years ago. The Sun is the source of the energy for these fossil fuels. The burning of fossil fuels releases CO 2 into the atmosphere.
Non-renewable energy sources Fossil fuels are non-renewable energy sources. Once the fuel has been used it is exhausted and cannot be replaced.
Renewable energy sources These are sources of energy that cannot be exhausted. Examples are: Solar Wind Wave Tidal Biofuel Hydroelectric Geothermal The Nesjavellir Geothermal Power Plant in Iceland The front of the Pelamis machine bursting through a wave at the Agucadoura Wave Park
Renewable energy is energy generated from natural resources—such as sunlight, wind, rain, tides and geothermal heat— which are renewable (naturally replenished).
Energy Density of a fuel The energy density of a fuel is the amount of chemical energy stored per unit mass of a fuel. Energy density= amount of energy mass of fuel mass of fuel The units for energy density are Jkg -1
The use of energy density A fuel with a higher energy density will be able to provide more energy per unit mass. The higher the energy density for a fuel, the more energy that can be transported for the same amount of mass of fuel.
Choice of fuel It seems that Uranium-235 would make the best fuel per kilogram because the energy density is very high. Is high energy density the only concern when choosing a fuel?
Choice of fuel Nuclear power stations are very expensive to build and the cost for the production of electricity per kilowatt-hr is more expensive than using fossil fuels. There are also political, social and environmental factors to consider.
Depending on use and storage of the fuel, the energy density is an important consideration Chemical composition and heating ability are other factors. Chemical composition of coal is in terms of its rank, moisture content, volatile content (% of coal lost as vapours), ash and fixed carbon.
Coal is divided into different ranks depending on the carbon and energy content per unit mass. Different ranks of coal will produce different amounts of heat. Rank of coal PeatLignite Bituminous coal Anthracite Carbon60%70%80%95% Energy5,500,0006,500,0007,800,0008,600,000
Because of the high content of volatile matter in peat and lignite, they cannot be transported for long distances because of safety risks. Usually, a power station is located where the mines are. Coal in some countries have a high sulfur content and this greatly affects the air quality in some areas. Australian bituminous coal and anthracite is low in sulfur and is a top export fuel in Asia.
Rate of world energy usage in terawatts (TW), 1965-2005 terawatts
Advantages and disadvantages of energy sources When considering which energy sources to use the following factors have to be considered: Cost of fuel Availability of fuel Transportation of fuel Environmental concerns (waste) Health concerns