Reliability
Which energy sources are the most reliable?
One way the energy industry measures the reliability of power plants is by calculating capacity factors.
The capacity factor measures how often a plant is running at maximum power. It’s expressed as a percentage and calculated by dividing the actual unit of electricity output by the maximum possible output.
Electricity sources in order of reliability with their capacity factor:
Nuclear energy is the most reliable with a capacity factor of 92.5%.
Natural gas 56.6%
Coal 40.2%
Hydroelectric 41.5%
Wind 35.4%
Solar 24/9%
Which energy sources are unreliable?
Renewable energy sources (wind, solar, hydroelectric) are the most unreliable, depending on the location. Some areas are sunnier, others windier. Sometimes the reservoirs are full, sometimes nearly empty.
How about reliability and storage?
Coal is difficult to extract but easy to store. Mine is extremely dangerous. In October 2020, a man died in a coal mine in Pennsylvania, and ten days before, two men died in a Kentucky coal mine. Once the coal has been extracted, it is easily stored for long periods of time.
Solar and wind power are readily available from nature but are not always available. The electricity is difficult to store because it requires a large battery capacity. Natural gas (or coal) provides backup electricity when there is no sun or wind.
Generally, renewable energy systems are subject to the whims of the weather, and we don’t have the battery capacity to store the energy for use during bad weather. In the winter of 2021, a predictable cold snap crippled the Texas power grid so even a reliable backup system wouldn't have helped.