Electricity Generation In The U.S. Continues To Become Increasing Green.  Large numbers of coal power plants are being retired.  Some are being replaced with natural gas, while others are replaced with renewable energy power resources such as wind farms and solar collectors.   This article focuses on both utility-scale commercial, and single-property renewable electricity generation.  Also discussed is Texas’ 3 Largest Wind Farms, soon to be 4.

In 2018, Wind accounted for 6.6% of electric generating capacity in the United States.    1/3 of utility-scale (power plant) electricity generating capacity added since 2007 has been Wind.  This was more than any other renewable technology, including hydroelectricity.

In 2000, Wind Generated Electricity In the U.S. Was 6 Billion kWh (KiloWattHours).  In 2018, Wind Produced Nearly 275 Billion kWh. ***

More Than Half Of U.S. Wind Capacity Is Located In These 5 States:

Texas              25,629 MW      Texas produces around 1/4 of all wind generated electricity in the U.S. 

Iowa                  8,957 MW

Oklahoma       8,072 MW

California        5,842 MW

Kansas              5,653 MW

Source: https://www.dallasnews.com/business/business/2019/08/13/wind-farm-can-power-168000-homes-blows-central-texas

In Iowa, Kansas, and Oklahoma—wind represents at least 25% of the state’s utility-scale generating capacity.  **  U.S. wind power supports around 115,000 American jobs, over 500 U.S. factories, and more than $1 billion a year in revenue for states and communities hosting wind farms.

Wind generated electricity comes with a major drawback.  When the wind isn’t blowing, no electricity is generated.  Just below, we go into detail as to why the power grid must always have a balance of electricity supply and demand.  Later we explain how wind & solar generated electricity must be supplemented by a back-up source, such as conventional power plants or battery storage.

Nearly Half Of NEW Power-Grid, Electricity Generating Capacity

Added During 2019 Will Come From Additional Wind Farms

Image Source: ShutterStock

In January 2019, The U.S. Energy Information Administration (EIA) stated: “A total of 10.9 GW in wind farms electricity generating capacity is scheduled to come online in late 2019.  Three states; Texas, Iowa, & Illinois will be home to more than half of 2019’s planned wind farm capacity additions.” *

During 2019 — 8 GW Of U.S. Electricity Generation Capacity Will Be Retired:

• 53% will be coal power plants.
• 27% will be natural gas
• 18% will be nuclear
• In 2018, one-third of all coal power plant retirements nationwide were in Texas.
• In 2019 (YTD) Texas has produced 21.4% of its electricity from coal and 21.8% from wind.  *3
• On June 1, 2019, the Pilgrim nuclear plant in Massachusetts shut down.  The electricity generated by the Pilgrim plant is replaced by the Vineyard Wind Farm, with 84 offshore wind turbines.
• Three Mile Island Nuclear Power Plant (the site of the United States’ worst commercial nuclear power accident) will be closed by Sept. 30, 2019. **

Today, Older Power Plants Are Being Retired 

Image Source: ShutterStock

Older, less efficient, & higher polluting electricity generating power plants are being retired.  Between 2017 to 2020, coal power plants will drop from 30% to 23% of all electricity generation in the U.S.   At the same time, the number of natural gas power plants will rise from 32% to 38% of all electricity generated.

Hydroelectric power generation will drop from 7.4% to 6.9% — as some hydroelectric power plants are being retired due to the damage they cause to the local environment.  Wind & solar will rise from 9.5% to 12.2% (likely even more).  2020 will present a notably cleaner electricity generating industry than existed only 3 years earlier.

NOTE: This number is for power plants only, and does not include solar rooftop installations that serve individual buildings.  Those details are just below.

In August 2019, The U.S. Energy Information Administration (EIA) quoted:

         2020    2017   Fuel / Resource (Billions Of kWh Per Day)

• 2.57       3.30      Coal
• 4.16       3.55      Natural Gas
• 2.16       2.20     Nuclear
•   .78         .82     Hydroelectric
• 1.37       1.05      Renewable – Non Hydroelectric

       11.17     11.05   Total Generation (Billions Of kWh Per Day)  *5

        TYPE                      2020   2017    % Of All Electricity Generated In the U.S.

• Coal                          23%     30%       -7%
• Natural Gas            38%     32%      +6%
• Nuclear                   1.9%    2.0%    -0.1%
• HydroElectric        6.9%   7.4%    -0.5%
• Wind & Solar       12.2%   9.5%   +2.7%

*3 Source: https://www.eia.gov/energyexplained/?page=biomass_home

*4 Source: https://www.eia.gov/tools/faqs/faq.php?id=427&t=3

*5 NOTE:  The sum of the individual numbers show above does not equal 100% because some electricity is generated using other fuels or resources such as; petroleum, geothermal, biomass (organic material that comes from plants & animals) and includes; wood, landfill gas (methane), and municipal waste. *3

What Will Happen To The Power Grid When Electricity Demand & Supply Don’t Match

And What This Has To Do With Wind Farms

Electricity must be consumed as it is generated, and must be generated as its consumed.  Electricity generation & demand must always be kept in constant balance.  As electricity demand increases, electricity supply must immediately increase proportionately.  Without that balance, the power grid will experience failure and a blackout occurs.  Just below is a well documented history of one such event.

How A Power Transmission Line Touching A Tree Led To One Of The Largest Blackouts In U.S. History

In August of 2003 one of the largest blackouts in U.S. history occurred in the northeastern U.S. and northeastern Canada.   Due to very high electricity demand, a power transmission line in Ohio became overheated and dropped downward.  The drooping transmission line then touched some overgrown trees.   If an electricity power line touches a tree, the tree creates a short circuit by allowing massive amounts of electricity to flow through the tree and into the ground.   If a short circuit occurs, a power line disconnects to protect itself.  Otherwise, it would be destroyed by more electricity flowing through it that it is designed to carry.

That transmission line that touched the tree disconnected itself.  The resulting 3,500 megawatt (MW) power surge (caused by the disconnected transmission line) should have caused an alarm to sound to alert power plant operators that a substantial imbalance in electricity demand and supply exists.  But the alarm did not sound.

When a large power transmission line disconnects for any reason, the electricity load switches to other line(s).   As a result of the first disconnected transmission line, electricity was forced into other transmission lines to shoulder the extra burden.  By 4 pm, three additional transmission lines (now overloaded) sagged into trees and also disconnected.   This caused a Cascading Failure of the power grid throughout southeastern Canada and eight northeastern U.S. states.  50 million people lost power for up to two days.

When electricity demand suddenly drops, power plant generating units disconnect to protect themselves.  During this blackout, more than 508 generating units at 265 power plants shut down.  In the minutes before the event, the local power grid was operating at 28,700 MW.  At the height of the outage, only 5,716 MW of electricity was being transmitted, a loss of 80% of the electricity that was flowing before the blackout.

So What Does This Have To Do With Wind Farms?

When the wind isn’t blowing, or blowing too hard, no electricity is generated at a wind farm.  Also, Wind Farms generate most of their electricity at night when electricity demand is lowest.  Additionally, on windy days the amount of electricity generated at an individual Wind Farm may exceed current electricity demand.   If this occurs, some wind turbines must shut off to maintain a balance of electricity demand & supply at all times.  *4

Also, with wind turbines there is a specific wind speed that causes the turbine to produce at maximum capacity.  This is called Rated Power (it varies by turbine brand and model).  Once the wind speed exceeds the Rated Power wind speed, the power generated by the turbine remains constant.  If the wind speed gets too high, it reaches the turbine’s Cut Out Speed (around 55 mph).  Then the wind turbine shuts down to prevent unnecessary strain.  So, too little wind (< 9 mph) or too much wind (> 55 mph) means no electricity is generated from a wind farm. 

When A Wind Farm Is Not Producing Enough Electricity

Nearby Power Plants Must Make Up The Difference Between Current Electricity Demand & Supply. 

Traditional Power Plants Use Steam Turbines To Generate Electricity.

• A fuel source such as; coal, oil, natural gas, or nuclear energy produces heat.
• The heat boils water to create steam.
• The steam spins the turbine.
• The spinning turbine turns the generator.
• The spinning generator produces electricity.

When needed for back up power to wind farms, fuel is constantly being used to ensure steam is available at a moment’s notice.  Wind power is somewhat predictable, so only some generator(s) must be available during times when electricity supply from the wind farm can’t meet electricity demand.   With a wind farm, there are times when the power plant generators are not needed, as the wind farm is supplying all the electricity needed.  Keeping power plant generators fired up and able to engage at a moment’s notice wastes fuel and adds to air pollution.

Battery Farms: A Solution To Minimize The Need For

Back Up Power Plant Generators To Be Fired Up & Ready At All Times

Image Source: ShutterStock

To maximize the potential of wind farms, excess energy generated must be stored until it’s needed.  This has created a new industry: Battery Farms.  The batteries are located near the wind turbines (or solar panels).   When the amount of electricity generated exceeds current demand, the excess electricity goes into battery storage.   When current generation can’t meet electricity demand, the system draws the additional power needed from the batteries.   Batteries allow wind farms & solar farms to provide electricity at their maximum potential.  Without batteries, traditional power plants are required to engage if electricity demand exceeds supply.

Tesla, the electric car company, is making many of the batteries used in Battery Farms.  In 2017, the largest battery storage power station in the world, the Hornsdale Power Reserve, (adjacent to the Hornsdale Wind Farm) became operational near Jamestown, South Australia.     The wind farm consists of 99 wind turbines and has a generation capacity of 315 megawatts.

*** Source: https://www.eia.gov/energyexplained/index.php?page=wind_electricity_generation

*4 Source: https://www.scientificamerican.com/article/wind-power-turbine-storage-electricity-appliances/