EIA: “About 25% of U.S. energy crops can begin up inside an hour”

EIA: “About 25% of U.S. power plants can start up within an hour”

Guess "did you know?" by David Middleton

In a world in which the construction of power plants (solar & wind) is mostly unreliable, backup power generation is becoming more important every day. The unreliable generation capacity in the US has doubled since 2013 and is now 12% of our generation capacity. The emergency power supply must be able to be started up quickly, ideally within minutes, safely in less than 1 hour.

NOVEMBER 19, 2020
About 25% of US power plants can be commissioned within an hour

Approximately 25% of US power plants can be up and running in an hour – from downtime to full operation – based on data gathered from the annual EIA survey of power generators. Some power plants, especially those that run on coal and nuclear fuel, take more than half a day to reach full operation. The time it takes for a power plant to reach full operation can affect the reliability and operation of the power grid.

The starting time of the generator differs depending on the power generation technology due to the different complexity of the power generation processes, especially when restarting after all processes have been stopped (cold shutdown). The start time of a generator differs from the ramp rate of a generator, which indicates how quickly this generator can change its output after operation.

Most hydropower turbines, which use a turbine spinning with running water, can go from cold start to full operation in less than 10 minutes. Combustion turbines, which use a burned fuel-air mixture to rotate a turbine, also operate relatively quickly.

Steam turbines often take longer. A fuel heats water to form steam, and that steam must meet certain thresholds of temperature, pressure, and moisture content before it can be sent to a turbine that can turn the power generator.

Nuclear power plants use steam turbines, but these plants have additional time consuming processes that manage their nuclear fuel. Almost all nuclear power plants take more than 12 hours to reach full operation. Power plants that take more than 12 hours to start up are becoming increasingly rare. Only 4% of the generation capacity that went online from 2010 to 2019 takes more than half a day to reach full load.

Natural gas combined cycle power plants, which use both a steam turbine and a combustion turbine, offer more capacity than any other generation technology in the USA. Most of these systems can be fully operational in 1 to 12 hours, but some can be started within an hour.

The percentage of the generator fleet not answering this question in the EIA survey has increased from 6% in 2013 when EIA first collected this data to 12% in 2019 due to the number of utility-scale solar and solar systems doubled wind turbines added in recent years. This question is not relevant for these plant species.

Main person responsible: Owen Comstock


63% of US generation capacity takes more than 1 hour to go from cold start to full load.

Source: US Energy Information Administration, Annual Inventory of Power Generators

Hydropower turbines are the fastest from cold start to full load.

Source: US Energy Information Administration, Annual Inventory of Power Generators
Note: Only technology / fuel combinations with at least 10 gigawatts of operating power are displayed.

The concept is not applicable to game and sun. In the example below, a wind turbine begins producing electricity when the wind speed exceeds 8 miles per hour (mph), reaches full power at 31 mph, and explodes at 55 mph (/ Sarc). To quote Sammy Hagar, "I can't drive fifty-five!"

The power curve: Note that the specific wind speeds vary depending on the type of turbine. (Photo credit: Sarah Harman, DOE)

On sunny days it takes about 4 hours for the solar PV to reach full power from a cold start. It works for about 4 hours and then slows down for about 4 hours.

Solar PV keeps the bank hours. (DOE)

Unless the weather is bad.

Solar does not show up for work on cloudy days. (DOE)

Fortunately for those of us who like to have electricity at night, on cloudy days, and on days with too little or too much wind, the combined natural gas cycle is the power generation source, primarily replacing coal.

Source: US Energy Information Administration, Annual Generators Report and Preliminary Monthly Generators Inventory

And we all know where this cheap natural gas comes from …


How about Sammy Hagar?

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