Low-Energy Fridays: What does less wind mean for the power industry?

After decades of yearly increases, the amount of electricity generated by wind power in the United States saw a slight decline in 2023. American wind generators produced 425.2 billion kilowatt hours (kWh) of electricity in 2023—2.1 percent lower than the 434.3 billion kWh generated in 2022. But reduced wind-generating capacity isn’t to blame; in fact, the total installed capacity for wind continued to increase in 2023 (albeit at a slower rate than in recent years).

So, what gives? One possibility is that transmission congestion is preventing wind power from getting to where it is needed. Effectively, this lack of transmission is driving up the cost of electricity in some parts of the country. The added costs to consumers from transmission congestion more than tripled between 2020 ($6.7 billion) and 2022 ($20.7 billion). However, while transmission congestion is a growing problem, it didn’t cause the fall-off in wind generation. Last year’s decrease in wind generation was confined to the upper Midwest, whereas other parts of the country saw a slight increase. Analysis of transmission, by contrast, shows the most severe congestion centered in and around the Great Plains.

Instead, it seems the reason for 2023’s decrease in wind generation is simpler: there was just less wind. We all know that wind is a variable resource. Sometimes it blows, sometimes it doesn’t. This variability is often predictable. For example, wind in West Texas tends to blow more at night than during the day. System operators use these predictable regularities when planning how to build out the grid while ensuring continued reliability.  

You might think these differences would average out over a long enough timespan and a big enough geographical footprint. The wind might blow more in the winter than in the summer, but because every year has a winter and a summer, there’s no reason to think one year will be windier than the next.

As it turns out, this is only somewhat true. Weather is a complicated business, and sometimes weather patterns contribute to a long string of less windy or more windy days that isn’t averaged out over a year. For example, data from the Electric Reliability Council of Texas, which operates the grid throughout most of the state, shows variation in the average weighted wind speeds from 2008 to 2021—from just under 8 to just over 10 miles per hour (MPH).

Exacerbating the issue is the fact that the amount of power generated by the wind does not increase linearly, but rather by the cube of wind speed. In simple terms, this means a wind turbine will generate around half as much power when the wind blows at 8 MPH as it will at 10 MPH.

While the variability in windiness is real, it’s not something that we should, uh… blow out of proportion. In 2023, 10.2 percent of electricity consumed in the United States derived from wind. Thus, the slight decline in wind generation represents a rounding error in terms of total electricity production. Of course, grid operators will want to consider the early variability in windiness during system planning. But a reliable grid does not require all resources in the system to operate at a consistent rate at all times (an impossible criterion). Ultimately, the key to maintaining a functional grid is to have a suite of energy sources available to meet electrical demand.