Wind energy is currently the largest source of renewable energy in California, making up 40 percent of the state’s renewable energy capacity and six percent of total electricity. This makes California the third largest producer of wind energy in the country, and employs between 3000 and 4000 people.

Although this is a significant amount of electricity generation, it occurs in only a few parts of the state. Namely, turbines are located in the Tehachapi area in Kern County near Bakersfield, in the Altamont Pass area in Alameda near San Francisco and in the San Gorgonio Pass in Riverside County near Palm Springs.

So how do we harness this wind energy, and how should we continue to do so moving forward?

Types of Wind Turbines

As it turns out, there are multiple types of wind turbines and different ways we can classify them. For starters, “wind turbines” produce electricity which can be put into the grid and used residentially or commercially; “windmills” often look more old-fashioned and do work that can be used to grind (mill) grains or pump water. But we can also classify wind turbines by their location and design.

  • Horizontal axis vs. vertical axis turbines: Although the classification system here is very literal, it can be harder to picture what a turbine with a vertical axis would look like. Horizontal axis wind turbines are the fairly standard turbines we see and recognize; they essentially look like a giant floor fan with three blades. By contrast, vertical axis wind turbines are less common and have more variation, as depicted below. While vertical axis turbines can be grouped more closely together and don’t have to be facing a certain direction to catch wind, they are currently less reliable and breakdown faster because the blades take more wear-and-tear. Because of this, vertical axis turbines are not currently scalable, and California wind companies have not shown much interest.
  • Onshore vs. offshore wind: The difference here is pretty obvious, with onshore wind being the turbines we see on land and offshore wind being turbines in the ocean. While offshore wind has taken off some in Europe, California’s wind energy comes exclusively from onshore turbines. The underwater terrain is particularly uneven, and thus harder to tether turbines into the ground. So far, only one company has applied for a lease to develop offshore wind.

The diagram below depicts the basic operation of a horizontal axis wind turbine, with wind turning the turbines blades which then spin the gears in the electricity generator.  Because horizontal axis onshore wind farms are by far the most common in California, we will focus on these turbines.

Photo: EPA

Wildlife Problems and Solutions

Of course, one of the great concerns with wind turbines is that they induce bird deaths, but this is only true when wind projects are poorly sited (meaning they are built in dangerous locations and with dangerous designs). The Altamont Pass, a large wind farm outside of the San Francisco area, is the prime example of poorly sited projects, and has killed thousands of birds.

Audubon California and local chapters like Golden Gate and Ohlone Audubon have worked tirelessly to make the wind turbines at Altamont Pass less deadly (read about one such activist here). Our work has been driven by the understanding that in order to prevent more tragedies like the Altamont Pass, the first and most important consideration is the location of wind farms. So what makes a location good? 

  1. Avoiding major migration routes: As most birders recognize, birds don’t fly with an equal distribution throughout the sky. Instead, there are particular corridors with heavy traffic along migration corridors—at Audubon you may have heard us call them flyways. Wind farms should be built to avoid these areas to cut down on the number of birds likely to fly near the turbines. And if wind farms do happen to be built along migration routes, the turbines should be shut down in the winter during key migratory times.
  2. Avoiding habitat fragmentation: Habitat fragmentation occurs when the wind turbines and the other infrastructure associated with wind farms cuts through important bird and wildlife habitat. In particular, this can mean forest or grasslands. In order to avoid this impact, windfarms should be placed near already-developed areas with road and powerline infrastructure already established.

The above recommendations ore critical for new wind projects, but unfortunately can’t do much for existing wind farms. And poorly sited wind farms—such as the Altamont Pass, which lies on a vital migration path for American Kestrels, Red-tailed Hawks and Golden Eagles—can’t really change their location now. While there are many proposed technological solutions and an unfortunately few number of solutions that have been proven, here are a few that Audubon California believes can be positive steps:

  • Larger wind turbines:  Although making wind turbines larger to protect birds may sound counterintuitive, larger turbines are actually better for wildlife. This is because larger turbines produces significantly more energy—so even if one large turbine kills more birds than one small turbine, the birds killed per amount of electricity produced decreases with bigger turbines.
  • Shut down systems: As you might expect, most turbine-related bird deaths come from birds colliding with the spinning blades of the turbine as opposed to the tower and base of the turbine. As such, one proposed technical solution is to use radar and GPS technology to detect nearby birds. When the birds are detected and headed dangerously close to the wind farm, the turbines can be shut off until the threat passes. While these methods show promise, they have not been statistically proven to be effective. As such, better siting of wind farms is still the best option.

Audubon California supports renewable energy when it is sited properly to avoid, minimize or mitigate effectively for impacts on birds, other wildlife and habitat.

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