Base load and peak load

• In the case of using only one power plant, the
capacity of the power generation will be defined
according to the peak value
• The plant will operate at a part of load for prolonged
time, which decreases the efficiency
• Several smaller units are installed with some of them
covering base load and others covering peak load
• The units that cover the base load operate
continuously, while those taking the peak load
operate when required
• All units operate near their rated power with high
efficiency

The generating units that operate as base power
plants should have the following characteristics:
• Low operating cost since they operate
continuously
• High capability of operating continuously for long
time
• Low and fast maintenance requirements
• The load factor is very high and reaches unity for
many units
Thermal, nuclear and hydraulic power plants are
conventionally considered as base load plants

The units that operate as peak power plants should
have the following characteristics:
• Very fast response to load variation (high ramp rate)
• Low startup time
• Low start up cost
• Low capital cost for economic operation since they
operate for relatively short time during the year
• Constant voltage and frequency against the load
fluctuations
• The load factor is very low in the range of 0.1-0.6
Steam, gas turbine and diesel power plants are
used as peak power plants