U.S. daily windpower supply varied 47% from high to low in mid’-September 2021
U.S. Electric Power Supply Review
Hourly & Daily
September 15 - 21, 2021
U.S. States with the greater windpower production are shown in darker shades. Gray shading indicates no utility-scale wind turbine generators installed.
Quick summary
windpower
9.04% of total electric energy generated in the period
strongest in late evening and early A.M. hours most days
high-to-low daily totals differed 47%
solar electric
2.58% of total electric energy generated in the period
high-to-low daily totals differed 20%
all non-combustion
wind, solar, nuclear and hydroelectric combined supplied 35.25% of total electric power generated
Note: see APPENDIX for discussion of Time Zones, Data Source, and Transmission Access
U.S. hourly electric power supply
September 15-21, 2021
Natural gas and coal combustion contributed the largest share of electric generation for the September 15-21, 2021 period.
Non-combustion energy sources — wind, solar, nuclear and hydroelectric — combined supplied 35.25% of total electric power generated in the United States contiguous 48 States during the period.
Hourly electric generation from combustion and non-combustion energy sources. U.S. Energy Information Administration chart created from Linecurrents.live custom query. Times are Eastern zone.
Electric generation from combustion and non-combustion energy sources. Linecurrents.live chart, U.S. Energy Information Administration data.
Solar electric
Solar production maximums in the chart are shifted from 11 AM - 1 PM to 1 - 3 PM due to chart times are Eastern zone, and largest solar supplies are in Texas (Central) and California (Pacific).
Hourly electric generation from solar energy sources. U.S. Energy Information Administration chart created from Linecurrents.live custom query. Times are Eastern zone.
Windpower
Windpower generation produced late-evening and early-overnight highs in each of the seven days. Lowest windpower production day was September 15.
Hourly electric generation from wind energy sources. U.S. Energy Information Administration chart created from Linecurrents.live custom query. Times are Eastern zone.
Daily electric generation from wind energy sources. U.S. Energy Information Administration chart created from Linecurrents.live custom query. Times are Eastern zone.
Combined wind and solar electric
Wind and solar electric energy daily production were complementary. Solar electric production increased mid-mornings when windpower declined, and wind increased most evenings as solar declined.
The second chart in this section shows hourly wind and solar electric production combined. The resulting total is the top edge of the green area.
Hourly electric generation from solar and wind energy sources. U.S. Energy Information Administration chart created from Linecurrents.live custom query. Times are Eastern zone.
Hourly electric generation from solar and wind energy sources. U.S. Energy Information Administration chart created from Linecurrents.live custom query. Times are Eastern zone.
Regional windpower:
highest production overnight
Texas, the Midwest, Central/Great Plains, California and northwest States are regions of greatest windpower. Maximum electric energy generation usually occurred late-evenings or overnight in these zones September 15-21, 2021.
Northwest
Hourly wind electric generation September 15-21, 2021 did not reveal a daily pattern in the Northwest region. The top windpower producing States are Colorado, Washington, Oregon and Wyoming.
Hourly electric generation from wind energy sources. U.S. Energy Information Administration chart created from Linecurrents.live custom query. Times are Eastern zone.
California
Strongest windpower generation occurred evenings and overnight in California, except September 20 and 21. Lowest production occurred September 21.
Hourly electric generation from wind energy sources. U.S. Energy Information Administration chart created from Linecurrents.live custom query. Times are Eastern zone.
Texas
Texas is the highest windpower producing U.S. State. The late-evening and early-overnight maximum production pattern was consistent in all but the last day of the September 15-21 period.
Hourly electric generation from wind energy sources. U.S. Energy Information Administration chart created from Linecurrents.live custom query. Times are Eastern zone.
Central
Windpower generation in the Central region did not follow a consistent daily pattern September 15-21, 2021. Lowest daily production occurred September 18.
Hourly electric generation from wind energy sources. U.S. Energy Information Administration chart created from Linecurrents.live custom query. Times are Eastern zone.
Midwest
Hourly wind electric generation September 15-21, 2021 was highest in late evenings, except September 18 and 21.
Hourly electric generation from wind energy sources. U.S. Energy Information Administration chart created from Linecurrents.live custom query. Times are Eastern zone.
The next section examines the hourly impact of removing all combustion electric supply from the U.S. contiguous 48 States’ three electric transmission grids, and increasing wind and solar electric generating capacity by a factor of seven. Results assume that new wind and solar electric plants are at existing sites, and perform the same as older units. Other new sites, such as off-shore windpower, may produce daily or seasonal production patterns which differ from existing sites.
September 15, 2021
U.S. non-combustion & total hourly electric supply
Total U.S. hourly generated electric energy supply is shown by the gray line in the following series of daily charts. Total includes includes wind, solar, hydroelectric and nuclear shown by color areas, as well as natural gas, coal, petroleum and other. Electric energy imported via electric transmission lines from Canada and Mexico are not included.
The first chart shows actual hourly electric generation. September 15 was the lowest windpower production day of the 7-day period.
Linecurrents.live chart, U.S. Energy Information Administration data. Times are Eastern zone.
September 15, 2021
7X wind & solar
In the following examples, actual hourly U.S. contiguous 48-States solar and wind electric energy supplies are multiplied by 7. These expanded non-combustion sources, combined with existing nuclear and hydroelectric power generating capacity, would have been inadequate to replace combustion generation sources during all hours of September 15, due to low windpower supply.
Actual wind and solar hourly electric supply for September 15 are shown as dashed lines.
Linecurrents.live chart, U.S. Energy Information Administration data. Times are Eastern zone.
September 16, 2021
7X wind & solar
If wind and solar electric energy generation were each increased by 7 times, these sources combined with existing nuclear and hydroelectric power generating capacity would have been adequate to replace combustion generation nearly all hours September 16. Oversupply captured in batteries or other systems storage systems may be released during the brief evening real-time generation shortage.
Linecurrents.live chart, U.S. Energy Information Administration data. Times are Eastern zone.
September 17, 2021
7X wind & solar
A U.S electric supply consisting of existing nuclear and hydroelectric, plus 7X wind/solar, would have been inadequate to replace combustion electric generation day September 17, 2021. Actual solar and wind electric generation were lower compared to most days of the 7-day period.
Linecurrents.live chart, U.S. Energy Information Administration data. Times are Eastern zone.
September 18, 2021
7X wind & solar
The hypothetical 7X wind/solar plus existing nuclear and hydroelectric generating scenario would have would not have produced enough electric energy to match actual September 11, 2021 power supply which included coal and natural gas combustion sources.
Linecurrents.live chart, U.S. Energy Information Administration data. Times are Eastern zone.
September 19, 2021
7X wind & solar
The hypothetical 7X wind/solar plus existing nuclear and hydroelectric generating scenario would have been adequate to replace combustion electric generation in all hours September 19, 2021 — the 3rd highest day for wind actual electric generation of the 7-day period.
Linecurrents.live chart, U.S. Energy Information Administration data. Times are Eastern zone.
September 20, 2021
7X wind & solar
Another day in which 7X wind/solar plus existing nuclear and hydroelectric generating would have been adequate to replace combustion electric generation in all hours. September 20 was the highest day for wind actual electric generation of the 7-day period.
Linecurrents.live chart, U.S. Energy Information Administration data. Times are Eastern zone.
September 21, 2021
7X wind & solar
Actual windpower production remained relatively strong in the afternoon September 21, compared to the previous 6 days. Solar electric supply was the lowest of the 7-day period. In a U.S. electric grid enhanced with 7X wind/solar an no combustion generation, oversupply captured in batteries or other systems storage systems earlier in the day may be released during the evening generation shortage.
Linecurrents.live chart, U.S. Energy Information Administration data. Times are Eastern zone.
Appendix
time zones
Hourly charts in this report are based on Eastern time. Compared to local time at generator sites, hourly MWhr results are shifted to later in the day if the generator is not in the Eastern time zone:
1 hour: Central time zone - Midwest, Great Plains, Texas
2 hours: Mountain time zone
3 hours: Pacific time zone - Northwest, California
data source
U.S. Energy Information Administration (EIA) Hourly Electric Grid Monitor is the source for data for this report. EIA provides this disclaimer:
Disclaimer: The information submitted by reporting entities is preliminary data and is made available "as-is" by EIA. Neither EIA nor reporting entities are responsible for reliance on the data for any specific use.
transmission access
Factors which may affect future electric power transfers among U.S. regions
inadequacy of existing transmission grid to move large amounts of electric power between regions
new transmission line construction right-of-way acquisition and State/local jurisdiction issues
States, Balancing Authorities and regions priorities for use of potential excess variable wind/solar electric energy:
a) export to other BA’s or regions
b) store and consume with no export
c) consume electric energy when produced by electrification of transport, water and indoor space heating, and other fuel-switching to electric energyhydroelectric supply reduction due to drought
nuclear electric supply reduction due to plant closures
other