Colorado & Wyoming hourly electric power - June 1-15, 2021

Map: Colorado and Wyoming utility-scale windpower sites, electric transmission lines, and Balancing Authorities.^{(1), (2)}

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• Reliable sunny mornings started the daily solar electric generating cycle.

• Erratic wind conditions did not produce a consistent daily wind electric pattern.

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Two Balancing Authorities monitor Colorado’s electric power supply, as shown in the map above:

• Western Area Power Administration - Loveland Area Office (WACM)

• Public Service Company of Colorado (Xcel Energy - PSCO)

The U.S. Energy Information Administration (EIA) explains the role of Balancing Authorities:

A balancing authority ensures, in real time, that power system demand and supply are finely balanced. This balance is needed to maintain the safe and reliable operation of the power system. If demand and supply fall out of balance, local or even wide-area blackouts can result.

Balancing authorities maintain appropriate operating conditions for the electric system by ensuring that a sufficient supply of electricity is available to serve expected demand, which includes managing transfers of electricity with other balancing authorities. Balancing authorities are responsible for maintaining operating conditions under mandatory reliability standards issued by the North American Electric Reliability Corporation⁽³⁾ and approved by the U.S. Federal Energy Regulatory Commission⁽⁴⁾ and, in Canada, by Canadian regulators.

EIA collects the data for the Hourly Electric Grid Monitor⁽⁵⁾ from its Form EIA-930, Hourly and Daily Balancing Authority Operations Report, which includes hourly electricity demand, forecast demand, net generation, and interchange data. The data are provided by the 65 electricity balancing authorities that operate the electric grid in the Lower 48 states and maintain real-time balance between electricity demand and supply on the grid.

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Hourly electricity generation data supplied to EIA by Western Area Power Administration does separate Colorado and Wyoming. Therefore, charts below show results for both States.

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Electric energy generated to supply consumer demand follows a daily pattern

Figure 1 (below) shows hourly totals of electric megaWatthours generated from all energy sources for Colorado and most of Wyoming. These electric energy sources are:

• wind turbines

• solar panels

• combustion natural gas and coal power plants

• hydroelectric dams

• other, such as biogas methane

Figure 1: Hourly electric generation from all sources for Colorado and Wyoming: June 1-15, 2021. Linecurrents.live chart. (Data glitch: June 2 at 3 PM)

A daily pattern of least electric generation before dawn and maximum generation during late afternoon and early evening was consistent for the first half of June 2021 in Colorado and Wyoming.

Hourly total electric generation approximately equals total consumer demand. Colorado electric utilities have little battery capacity to store variable mid'-day solar or overnight windpower for use during peak consumption hours.

Keeping electric generating supply in balance with consumer demand is required to keep the U.S. electric grid spinning at 60 Hertz (Hz, cycles per second). Excess generation causes this alternating current (AC) frequency to increase, a condition called overfrequency. Not enough generation causes a frequency reduction: underfrequency.

Since wind and solar electric supplies are variable, combustion power plants compensate for changes in solar/wind output and consumers’ demand by increasing or decreasing the fuel supply.

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Windpower supply - some days good, some not

Daily wind-generated electric power was inconsistent July 1 - 15, 2021. Six days show morning increases beginning 2 - 3 hours after consumer demand climbed. Evening performance was better, as windpower output increased before or during evening consumption peaks in all but 3 days. <Fig. 2 below>

Fig. 2: Hourly wind electric generation - Colorado and Wyoming: June 1-15, 2021. Linecurrents.live chart.

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Windpower increased in late afternoon . . . or not

An example of beneficial wind conditions was June 12, as electric power generated by Colorado and Wyoming wind turbines increased in the evening concurrently with the total electricity generated to supply to consumers’ demand. Solar electric generation dropped in the middle of the late afternoon peak demand period. <Fig. 3 below>

Fig. 3: Hourly wind, solar and total electric generation - Colorado and Wyoming: June 12, 2021. Linecurrents.live chart.

. . .

Wind conditions were not favorable for electric generation on June 11, when wind turbine output decreased as consumer demand increased. <Fig. 4 below>

Fig. 4: Hourly wind, solar and total electric generation - Colorado and Wyoming: June 11, 2021. Linecurrents.live chart.

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Solar electric daily pattern: sunny, with a few afternoon clouds

Solar electric increased concurrently with the total electric generating supplied to consumers in early morning hours. Late-morning and afternoon declines reduced solar electric ability to support the late-afternoon peak demand in 7 days. <Fig. 5 below>

Fig. 5: Hourly solar electric generation - Colorado and Wyoming: June 1-15, 2021. Linecurrents.live chart. (Data glitch: June 2 at 3 PM)

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REFERENCES

1. Western Interconnection Balancing Authorities - January 5, 2017 map, Western Electricity Coordinating Council

2. U.S. Energy Information Administration Energy Atlas Electricity Energy Infrastructure and Resources

3. North American Electric Reliability Corporation

4. Federal Energy Regulatory Commission

5. U.S. Energy Information Administration EIA launches redesigned Hourly Electric Grid Monitor with new data and functionality