8.2.1 Identify different world energy sources
The main energy sources are:
Nearly all of the energy above comes from the sun. Electromagnetic radiation arrives at the Earth's surface and although most of it is reflected back into space, a small amount is absorbed by plants and used to generate organic compounds. The sun is also responsible for creating wind and waves.
8.2.2 Outline and distinguish between renewable and non-renewable energy sources.
Renewable Resources
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Non-renewable Resources
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Non-renewable resources can become renewable if the rate of replenishment exceeds the rate of consumption.
8.2.3 Define the energy density of a fuel.
Energy density is the amount of energy liberated per unit mass of fuel consumed (J/kg). It is also known as the potential energy stored in a fuel per unit mass or volume. The following table shows the energy densities for various fuels:
8.2.4 Discuss how choice of fuel is influenced by its energy density.
Fuel is determined by the transportation costs, which depend on the energy density of the fuel. Some fuels have high energy density and low transportation costs, but are expensive themselves, such as uranium. Some fuels depend on application. For example, nuclear power can be used in submarines.
8.2.5 State the relative proportions of world use of the different energy sources that are available.
(The above data is from the year 2009.)
8.2.6 Discuss the relative advantages and disadvantages of various energy sources.
The questions you need to ask yourself are:
- Does this fuel release greenhouse gases and contribute to global warming?
- Does this fuel pose a risk to human health or other living organisms?
- Does this fuel pollute or pose a threat to the environment?
- Is fuel source renewable or non-renewable?
- Is this fuel expensive?
- Does this fuel have a high or low energy density?
- Is the fuel continuously available or is it dependent on factors such as weather or time of the day/night?