Throughout history, humans have used wind energy to propel sailboats, power machines, pump water, and grind grain and corn. Wind turbines convert kinetic energy from the wind into mechanical power, or they can produce electricity using a generator. In the late 1800s, the first wind turbine was used in Scotland to produce electricity.
Since the early 2000s, wind power generation has increased significantly across the globe. In 2020, wind turbines met 8.4% of the U.S. energy demand and 16.4% across the EU and UK.
Wind turbines can power onsite loads, charge batteries and electric cars, private homes, or supply electricity to the utility grid. They can also power villages, towns or even entire cities, as wind farms get increasingly bigger in terms of number of turbines and production capability.
But just how much can wind turbines power? The capacity of the wind turbine determines the loads it can power and varies significantly by the size of the turbine.
What Can a Residential Wind Turbine Power?
Home wind turbines are commonly 15 kw or less and can power lights, appliances, and electronics. They are used for both off-grid and grid-tied applications and sometimes contain energy storage capabilities such as batteries. When adequately sized, a residential wind turbine can power an entire home. In addition, if it has energy storage batteries, it can have electricity even during blackouts.
To reduce the size of the equipment, renewable energy experts often recommend starting with energy-efficiency improvements before installing a wind or solar energy system. For example, replacing incandescent light bulbs with energy-efficient LED bulbs and swapping out inefficient appliances can reduce the size of the wind turbine, reducing the cost of the wind installation.
How would I size a home wind turbine?
When sizing a home wind turbine, it is essential to consider the total household electricity consumption. Looking at a year or more of electricity bills is the best way to determine the actual consumption for a particular house or apartment.
Homeowners can also decide whether they anticipate using more electricity in the near future and consider this when sizing the wind turbine. For example, if a home is purchasing an electric vehicle and plans to charge at home, electricity use will increase.
Across much of Europe, a typical home consumes about 4,000 kWh annually, but average electricity use is about four times higher in Norway. In the U.S., the average home uses 10,700 kWh, more than double the average consumption in the EU.
However, the amount of renewable energy that wind turbines produce also depends on the location. In fact, wind patterns are usually highly seasonal and wind turbines often don’t operate at maximum power capacity. Therefore, wind energy installations in areas with good wind resources will produce more power than areas with less wind.
In much of the U.S. and Europe, wind energy production is highest in the winter and early spring and lowest in the mid to late summer. Home wind turbines usually need 11 kph (7 mph) wind speeds to produce electricity, so they are impractical in some areas and very productive in others.
When sizing a home wind turbine, it is also important to consider if the home is connected to the utility grid. If so, if the system is undersized, it will not impact the comfort of the residents if wind energy production is lower than consumption because the utility grid can supply electricity as needed. However, for off-grid homes, it is helpful to plan for times when the wind resource is poor and to have ample battery capacity for these period.
Utility-scale Wind Energy
What can a large onshore wind turbine power?
Whereas a residential wind turbine can power one home, utility-scale turbines can power many hundreds or even thousands of homes. The capacity factor of a wind turbine is the average electricity output divided by its maximum power capability, so it varies depending on the wind resource in an area.
The higher the capacity factor, the greater the electricity generation. The average capacity factor in Europe is 26%. But, the average offshore capacity factor is much higher at 38% compared to 24% onshore.
To calculate how much electricity a wind turbine produces involves knowing the capacity factor, the capacity rating of the wind turbine, and the time period.
With a 26% capacity factor, a 2-MW wind turbine would produce 2 MW × 365 days × 24 hours × 26% = 4,555 MWh or 4,555,000 kWh per year.
If the average European home consumes roughly 4 MWh of power, then the 2 MW turbine would power about 1,138 homes. However, in the U.S., where the average home consumes 10.7 MW of power annually, the same turbine would power only about 426 households. This highlights the importance of combining energy efficiency and renewable energy production to mitigate climate change and greenhouse gas emissions.
Can off-shore wind turbines power more homes than on-shore turbines?
The largest offshore wind turbines can have a significantly higher nameplate capacity than on-shore turbines, and they commonly have a higher capacity factor. For example, Siemens Gamesa has a 14-megawatt model and a 222-meter rotor diameter.
With a 38% capacity factor, a 14-MW wind turbine would produce 14 MW × 365 days × 24 hours × 38% = 46,603 MWh or 46,603,000 kWh annually.
For households that consume about 4 MWh of electricity, then a large off-shore wind turbine could power 11,651 homes. Therefore, one off-shore wind turbine could supply a small town with renewable energy, and a handful of offshore wind turbines can supply a small city.
Are wind turbines increasing in size and capacity?
The capacity and size of the average wind turbine have increased dramatically in the last couple decades. The average nameplate rating of newly installed onshore wind turbines in the U.S. was 2.75 MW in 2020, up 8% from 2019 and 284% since 1998-1999. As wind turbine capacity increases, the size of the wind turbines themselves has increased dramatically, including the turbine hub height and rotor diameter.
Greater nameplate capacity is largely a good thing for the wind energy industry because it makes it easier to decrease reliance on fossil fuels and produce more clean energy. However, large turbines create some transportation, construction, and decommissioning challenges due in large part to their size.