What is the difference between base load and peak load in electricity systems?

• A. Base load is nighttime demand.
• B. Base load is the minimum level of demand that continuously exists; peak load is the highest demand period requiring additional generation capacity or storage.
• C. Base load and peak load are the same.
• D. Base load is the energy produced by renewables.

Answer: (B)

The main idea here is how electricity demand on a grid behaves over time. Base load is the minimum level of demand that exists continuously, the steady floor the system must always meet. Peak load is the highest demand period, when usage surges and the grid needs extra generation capacity or storage to cover that spike. This matters for planning which plants run steadily versus which resources are used only during peaks. For example, a city might have a constant baseline around 600 MW, but on a very hot day demand could rise to 1,200 MW; meeting that extra demand requires additional capacity or storage. Base load isn’t defined by nighttime alone, and base load and peak load are not the same. It’s also not about renewables specifically—the term base load describes demand, while the energy sources used can vary with availability and capacity.