Peaking power plants, also known as peaker plants, and occasionally just "peakers," are power plants that generally run only when there is a high demand, known as peak demand, for electricity.[1][2]
Contents |
In the United States, this often occurs in the afternoon, especially during the summer months when the air conditioning load is high. During this time many workplaces are still open and consuming power.
The time that a peaker plant operates may be many hours, a day, or as little as a few hours per year, depending on the condition of the region's electrical grid. It is expensive to build an efficient power plant, so if a peaker plant is only going to be run for a short or highly variable time, it does not make economic sense to make it as efficient as a base load power plant. In addition, the equipment and fuels used in base load plants are often unsuitable for use in peaker plants because the fluctuating conditions would severely strain the equipment. For these reasons, nuclear, geothermal, waste-to-energy, coal, biomass and electrochemical energy storage systems are rarely, if ever, operated as peaker plants.
Peaker plants are generally gas turbines that burn natural gas. A few burn petroleum-derived liquids, such as diesel oil and jet fuel, but they are usually more expensive than natural gas, so their use is limited. However, many peaker plants are able to use petroleum as a backup fuel. The thermodynamic efficiency of simple-cycle gas turbine power plants ranges from 20 to 42%, with between 30 to 42% being average for a new plant.
For greater efficiency, a heat recovery steam generator (HRSG) is added at the exhaust. This is known as a combined cycle plant. Cogeneration uses waste exhaust heat for process or other heating uses. Both of these options are used only in plants that are intended to be operated for longer periods than usual. Reciprocating engines are sometimes used for smaller peaker plants.
The opposite of a peaking plant are base load power plants, which operate continuously, stopping only for maintenance or unexpected outages. Intermediate load following power plants operate between these extremes, curtailing their output in periods of low demand, such as during the night. Base load and intermediate plants are used preferentially to meet electrical demand because the lower efficiencies of peaker plants make them more expensive to operate.[3]
|
|||||||||||||||||||||||||