Blend of wind and solar electric reduces daily ups and downs of U.S. weather-dependent energy sources
Hourly & Daily U.S. Electric Power Supply Review
September 8 - 14, 2021
PV array and wind turbine generator at National Wind Technology Center (NWTC) located at National Renewable Energy Laboratory’s Flatirons Campus near Arvada, Colorado. U.S Department of Energy photo.
overnight windpower complemented daytime solar
consistent daily wind pattern in West and Central U.S.
less solar & wind Sept 8 & 9
Introduction
U.S. Energy Information Administration (EIA) Hourly Electric Grid Monitor is the source for data contained in the following charts. Please read EIA disclaimer in the Appendix.
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
Factors which may affect future bulk electric power transgrid transfers are not considered in this report. See Appendix for a list of these potential conditions.
U.S. States monthly electric generating totals by energy source may be compared at Linecurrents.live link to Energy Information Administration interactive maps and charts.
September 8-14, 2021
U.S. hourly electric power supply summary
Natural gas and coal combustion contributed the largest share of electric generation for the September 8-14, 2021 period.
Non-combustion energy sources — wind, solar, nuclear and hydroelectric — combined supplied 35.37% of total electric power generated in the United States lower 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.
Consistent daily solar energy, less reliable windpower
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). The lowest production day was September 9.
Hourly electric generation from solar energy sources. U.S. Energy Information Administration chart created from Linecurrents.live custom query. Times are Eastern zone.
Windpower generation produced late-evening and early-overnight highs in each of the seven days. Lowest solar production day was September 9.
Hourly electric generation from wind energy sources. U.S. Energy Information Administration chart created from Linecurrents.live custom query. Times are Eastern zone.
Wind and solar electric energy daily production were complementary, as solar energy production increased mid-mornings when windpower declined.
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 occurred overnight in these zones September 8-14, 2021.
Northwest
Windpower generation produced late-evening and early-overnight maximums all dates except September 8 in the region designated Northwest by the U.S. Energy Information Administration. The top windpower producing States in this region are Colorado, Washington, Oregon and Wyoming. September 9 was the lowest windpower production date.
California
Strongest windpower generation September 8-14, 2021 occurred late-evening and overnight in California. Lowest production occurred September 9.
Texas
Texas is the highest windpower producing U.S. State. The late-evening and early-overnight high production pattern was consistent September 8-14 , 2021. Lowest production occurred September 9.
Central
Windpower generation produced late-evening and early-overnight maximums in the Central region. Lowest production occurred September 8.
Midwest
Hourly wind electric generation September 8-14, 2021 did not reveal a daily pattern in the Midwest region. Lowest production occurred September 9.
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 8, 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.
Linecurrents.live chart, U.S. Energy Information Administration data. Times are Eastern zone.
September 8, 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 non-combustion energy sources, combined with existing nuclear and hydroelectric power generating capacity, would have been inadequate to replace combustion generation sources for most hours of September 8. Excess mid’-day solar energy oversupply, if stored in batteries or other systems, could be released during the evening shortage.
Linecurrents.live chart, U.S. Energy Information Administration data. Times are Eastern zone.
September 9, 2021
7X wind & solar
If U.S. 48 contiguous States’ 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 inadequate to replace combustion generation sources all hours September 9.
Linecurrents.live chart, U.S. Energy Information Administration data. Times are Eastern zone.
September 10, 2021
7X wind & solar
A U.S electric supply consisting of existing nuclear and hydroelectric, plus 7X wind/solar, would have been adequate to replace combustion electric generation for the entire day September 10, 2021. The energy oversupply of the first 18 hours, if stored, fills the evening electric generation shortage.
Linecurrents.live chart, U.S. Energy Information Administration data. Times are Eastern zone.
September 11, 2021
7X wind & solar
A U.S. electric generating fleet in which combustion energy sources are eliminated, and existing solar and wind plants increased by a factor of 7, would have produced more electric energy all hours of the day than was supplied by the existing generators all hours September 11, 2021.
Linecurrents.live chart, U.S. Energy Information Administration data. Times are Eastern zone.
September 12, 2021
7X wind & solar
The hypothetical 7X wind/solar plus existing nuclear and hydroelectric generating scenario is adequate to replace combustion electric generation in all but a few hours September 12, 2021. Energy oversupply of the first 19 hours, if stored, compensates for the evening electric generation shortage.
Linecurrents.live chart, U.S. Energy Information Administration data. Times are Eastern zone.
September 13, 2021
7X wind & solar
Another day of electric oversupply if combustion electric generating sources are replaced with 7-times the existing wind and solar U.S. generating capacity.
Linecurrents.live chart, U.S. Energy Information Administration data. Times are Eastern zone.
September 14, 2021
7X wind & solar
Windpower production was less in the evening hours September 14, compared to September 10 - 13. In a U.S. electric grid enhanced with 7X wind/solar, and combustion electric energy sources eliminated, storage systems could shift overnight wind and mid’-day solar oversupplies to fill some of the September 14 evening electric supply shortage.
Linecurrents.live chart, U.S. Energy Information Administration data. Times are Eastern zone.
Appendix
U.S. ENERGY INFORMATION ADMINISTRATION
HOURLY GRID MONITOR
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.
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 away from fossil fuelshydroelectric supply reduction due to drought
nuclear electric supply reduction due to plant closures
other