8.3.1 Outline the historical and geographical reasons for the widespread use of fossil fuels.
In the 1800s, heat engines were developed in the United Kingdom. Over the next century, intensive efforts went into improving the model and engines became widely used as an efficient source of energy. The change from physical labor to machinery is known as the industrial revolution. A demand for fuel began to arise and coal was the cheapest, most plentiful and most energy dense fuel at the time. Coal is an example of a fossil fuel -- fuels that are formed underground by the action of high pressure and temperatures in the absence of air over millions of years. Coal is formed from dead plants, while oil and natural gas are formed from deceased marine organisms. Fossil fuels have very high energy densities compared to most other fuels. They are also widely available, so nearly every region in the world began using them.
8.3.2 Discuss the energy density of fossil fuels with respect to the demands of power stations.
The demand of a power station is the amount of joules needed in a certain period of time to comply with the required energy at that moment. In simpler terms, it is the amount of energy that needs to be generated in order to satisfy the demand of a group of people. Fossil fuels have a high energy density so they are able to meet the current demand, however, as the demand increases, more fossil fuels need to be burned.
Energy density can be used to calculate power through the following formula:
The mass of fuel burned every second can also be defined as the rate of consumption.
Energy density can be used to calculate power through the following formula:
- Power output = efficiency x mass of fuel burned every second x energy density
The mass of fuel burned every second can also be defined as the rate of consumption.
8.3.3 Discuss the relative advantages and disadvantages of the transportation of fossil fuels.
Advantages
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Disadvantages
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8.3.4 State the overall efficiency of power production fueled by different fossil fuels.
Natural gas power stations are the most efficient types of power stations. They are able to convert nearly half of the chemical energy in gas to electricity (45% efficient). Efficiency can be raised if the excess thermal energy is used to heat houses, or if surplus heat from a gas turbine is used to heat water and produce steam.
The factors that affect the efficiency of power plants include:
The factors that affect the efficiency of power plants include:
- The type of fuel used
- The load factor (ratio of average energy demand to maximum demand during a period)
- Technology used
8.3.5 Describe the environmental problems associated with the recovery of fossil fuels and their use in power stations.
Problems with fossil fuels in power stations
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Problems with retrieval of fossil fuels
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Methods to ‘clean’ the fuels, such as removing salt from dissolved gas or pumping water to oil deposits have proven costly and inefficient.