Explain why fossil fuels are still used as the main energy resource for large-scale electricity generation, even though renewable energy resources are available.

Fossil fuels release a large amount of energy per kilogram of fuel, giving a high power output that is easy to harness for large‑scale electricity generation.
Renewable resources such as wind or solar cannot match this energy density; their power output is lower and varies with weather and time of day.
Because of this intermittency, renewables are not always reliable and cannot guarantee a continuous supply of electricity.
Fossil fuels therefore provide a continuous, consistent supply of energy on demand, which is essential for large‑scale power stations.