Most of the electricity that we generate today is done so by harnessing differential energy levels. Basically in order to get a turbine to spin, we have to have high pressure at the inlet of the turbine and low pressure at the outlet of the turbine. This should make intuitive sense because if you had equal pressures on both sides of a turbine there would be no flow, and the turbine would not spin. When you have a differential between two energy levels, the high energy state wants to flow to the low energy state and try to equalize. When energy starts to flow we can capture it and use it to turn a turbine. The bigger the differential is between the high energy state, and the low energy state, the more power that can be produced from the system.
The most common energy differential that is used to generate electricity is a temperature differential. When we can find or create a large temperature differential, we can easily convert that to a large pressure differential which can be used to spin a turbine. Some examples of creating a temperature differential are burning coal or natural gas. The energy that is on the hot end of the system is referred to as a heat source. Then there is also the cold side to take into account. Usually the cold side of the temperature differential is the ambient air temperature and it is referred to as a heat sink. So the greater the difference is between the heat source and the heat sink the more efficient the system will be. The heat source is used to boil water and turn it into high pressure steam for the inlet of a turbine while the heat sink is used to condense the steam and create a low pressure area at the outlet of a turbine.
There are also naturally occurring differential energy states. One example of this is a geothermal system. In the case of Geothermal, the heat below the earth’s surface acts as the heat source, and the ambient temperature acts as the heat sink. Another naturally occurring temperature differential is ocean thermal energy conversion. This technology harnesses the difference in temperatures between warm ocean surface temperatures as a heat source, and cold temperatures found deep in the ocean as a heat sink.
Pressure differentials also occur naturally and can be used to turn turbines. The most well-known example of this is wind. High pressure wind wants to flow to areas of low pressure. We can put a wind turbine in its path and capture some of that energy as it flows by.
Another form of differential energy that we capture to generate electricity is water in a high elevation that has a high potential energy. Gravity wants to pull this water down to a low elevation where it would have low potential energy. We capture the difference in potential energy in to form of hydroelectric turbines.
If you can recognize any other areas where there are differential states of energy, try to figure out a way to capture the difference and turn it into electricity.
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