Green energy, including wind energy, has slowly expanded to become a major player in the world energy market in 2019. The United States Energy Information Administration estimates that, as of 2015, renewable energy sources provided 12% of the world’s energy. That is set to expand to 17% by 2040. Wind energy is a significant component of this market.
Unlike its hydroelectric and solar power cousins, wind power has a truly tiny environmental footprint. While typical hydroelectric dams wind up flooding thousands of square kilometers, and solar panels require dozens of environmentally harmful chemicals to manufacture, wind power continues to maintain its reputation as one of the least harmful ways to generate large amounts of electricity known to man.
Read on below to find out what wind energy is, how it is captured, and what these marvels of design and engineering are made of. We’ll also discuss some of the downsides of wind energy, and whether those downsides should preclude the use of the technology altogether.
Wind Energy: Definition
So what is wind energy exactly? Wind energy is the energy that is generated by harnessing wind, or the movement of air around the planet, to make electricity. A few steps are necessary for this process but, overall, it’s a very simple procedure.
First, we need wind. The wind is caused by a number of factors including the uneven distribution of heat across the planet, irregularities on the earth’s surface, and the rotation of the earth itself. All of these factors combine to create large movements of air around the planet that we experience as the wind.
Second, we need a method of capturing wind and turning it into stored electricity. Wind energy devices fill this function. Turbines are effectively the opposite of room fans. In a fan, electricity is used to spin a set of blades, which creates wind. In a wind power device, wind spins a set of blades, which creates electricity. That electricity is either stored in a battery or is transmitted to an electrical grid. But how does a spinning blade create electricity you ask? Read on below to find out.
What’s in a Wind Energy Device?
At its simplest, a turbine consists of a number of components: the blades, a shaft, a generator, and a tower. It is, of course, a little bit more complicated than that, but those are the major components.
The idea is a simple one. The wind turns the blades, which are attached to a shaft. The shaft spins a generator, creating electricity. All of this is raised into the air and sits atop a tower, so as to better access the wind.
Now, as I already indicated, the simple idea of harnessing the wind to generate electricity gets a little bit more complicated in practice. For one thing, there are more components in a typical machine than the ones I’ve described. So, for example, a standard wind power creator will contain a large gearbox. The gearbox will convert the relatively slow rotation of the blades into the much faster rotation of the generator. This is because typical generators can only produce electricity at relatively high speeds, while typical blades can only rotate (without breaking) at relatively low speeds.
Standard wind energy creators will also contain controllers, which turn the entire system on when the wind reaches a certain speed, and off when it falls below a certain speed. They also operate to shut the system down when the wind rises above a certain speed (typically 55mph) because fan systems can be damaged by rotating at wind speeds above that level.
Finally, many wind energy systems contain a brake, designed to stop the system in an emergency or to keep the system from operating at too high of a wind speed.
How Much Power Does Wind Energy Produce?
The answer to this question depends entirely on the size of the turbine or wind farm. The largest wind energy towers produce the most energy because the blades provide more torque and can spin a larger and more powerful generator.
The largest machines are usually constructed on ships and placed offshore. These gigantic machines can produce up to 9.5 megawatts of electricity and often stand up to 160 meters tall. Their blades can extend out to 80 meters from the tower.
For illustration purposes, the largest wind energy towers in the world, the Vestas V164, produces an incredible 9.5 megawatts of energy. For offshore use only, the turbine stands 220 meters tall, with a wingspan of 164 meters.
At the other end of the spectrum are small household devices, designed to produce only enough energy to power a traffic light or a small battery charger. (Click this link to find out more about how much power wind turbines produce.)
The smaller contraptions designed to power household-level devices or supplement a single home’s power consumption are usually installed at or near the site of electricity consumption. In these cases, the power generated from the residential wind turbine device is referred to as “distributed wind.” The excess electricity from distributed wind is sometimes sold back to utility companies.
What Kind of Wind Energy Creators Are There
There are two major types of wind energy devices: the vertical axis turbine and the horizontal axis turbine. Both are useful for specific applications and choosing between them implies a tradeoff between features and shortcomings.
Vertical Axis Wind Energy Turbines
Referring to the vertical orientation of the main rotor shaft, vertical axis turbines are generally less sensitive to wind direction, which is handy in environments where wind direction can be highly variable and situational. They allow for the gearbox and generator to be placed on or near the ground. Generally speaking though, they produce less power and are less reliable over time.
Horizontal Axis Wind Energy Turbines
Horizontal axis machines have their main rotor shafts oriented horizontally. These turbines produce the vast majority of the wind energy in use today. They can be further subdivided into upwind and downwind towers, with the former having their blades upwind of the tower. Downwind devices are oriented so as to place the tower between the wind source and the blades. Upwind devices, although they must usually be manually oriented by what’s called a “yaw motor,” are preferred because of increased reliability.
Unconventional Wind Energy Turbines
There is a rarely used third category of turbines. These unconventional designs utilize neither a horizontally nor vertically oriented shaft. They are very rarely used for commercial or consumer purposes because of their inherent drawbacks or immature technology and are beyond the scope of this article.
What Are Wind Energy Devices Made Of?
A variety of composite materials make up commercially available wind power fan blades. Glass and carbon fibers provide a stiffness-to-weight ratio desirable in the construction of a powerful wind energy generator. Generally speaking, all glass-fiber construction is significantly less expensive but less durable than constructions incorporating carbon fiber. And while glass fiber is cheaper, it is also significantly heavier than carbon fiber.
Fascinating advances in materials are creating a revolution in wind power construction. The introduction of small proportions of carbon nanotubes can have remarkable effects on the durability and reliability of the fan blades. Unfortunately, these developments remain largely theoretical and have not yet reached widespread commercial use.
More immediately, the use of carbon-glass hybrid fibers has led to large increases in durability and decreases in the weight of the fan blades. Some of the longest blades in the world, which create some of the highest levels of energy in the wind power space, are made of these hybrid fibers. Research continues into the best way to incorporate and use the fibers.
Components other than the fans are made up of a variety of metals, usually steel and aluminum. These materials provide the strength and reliability required to support the extremely heavy and large blades present in the largest wind device constructions. They are also durable enough to withstand the torque and vibration caused by the rotation of the fan blades.
What are some Downsides to Wind Power Generation?
Despite their reputation for creating low-cost wind power with a low environmental impact, wind power does have its detractors. With complaints ranging from aesthetics to their impact on wildlife, the naysayers are making themselves heard. Some of these folks have even suggested that the drawbacks are powerful enough that they should lead us to ban the use of large-scale wind installations.
Beauty Is Just Skin Deep
For as long as there have been industrial-sized wind towers, there have been people who have decried their visual impact on the natural landscape. Many do not like the appearance of huge man-made constructs rising above the rural countryside.
Of course, the validity of this criticism depends largely on one’s personal taste or distaste for modernity. Many people like the vaguely futuristic aesthetic of a wind farm, with its dozens of gigantic fans rising triumphantly against the natural backdrop.
While there is no right answer, many insist that one’s ability to enjoy a natural vista is steadily being eroded by, among other things, wind farms. At some point, their voices may become loud enough to create significant resistance to the wind energy movement.
Impact on Animals
The fans on wind towers have led to the deaths of hundreds of thousands of birds across the world. Additionally, the humming noise created by wind farms is loud enough to disrupt the lives and habits of native species. Some conservationists have suggested that the cost associated with the installation of large wind power towers in wind farms is not worth the cost in wildlife disrupted, killed, and injured.
This impact, while significant, should not be exaggerated. Buildings and common housecats have killed far more birds to this point than even the most lethal turbines, and the impact of the relatively muted noise on animal species is inarguably far less severe than the impact to date of the climate change caused by the widespread use of fossil fuels.
People have pointed out that it is difficult, if not impossible, to recycle the materials used by the most advanced wind energy devices. This, it is said, militates against their further deployment as it creates yet more waste that can’t be recycled. There is a related criticism, insofar as the construction of certain kinds of advanced wind power generators requires the use of rare earth materials for magnetic drives. Use of those materials in wind power generation precludes their use in other, perhaps more economically advantageous, devices.
The response to these criticisms is that, while there might be some disadvantage attached to the creation of an unrecyclable fan blade, it pales in comparison to the environmental damage caused by a coal plant or other renewables, like hydroelectric dams.
As for the use of rare materials, people respond by noting that this problem exists in the manufacture of all devices requiring rare materials. The market should, and does, resolve the problem of allocation of scarce resources with reasonable efficiency.
Like solar panels, wind power generation runs the gamut from colossal beasts capable of generating millions of watts of electricity and powering significant proportions of the electrical grid, to tiny generators sitting atop traffic lights generating barely enough energy to power stop and go signals.
Made of a wide variety of materials, placed both onshore and offshore, in wind farms and on their own, and made in a wide variety of designs and material compositions, wind energy towers are versatile enough to be used almost anywhere the wind blows.
While they are not without their drawbacks, their minuscule environmental footprint and limited ecological effects make them prime candidates for green energy production. (Click this link for some more pros and cons of wind energy production!)
This is especially true when one considers the rapid and significant advancements being made with respect to the materials and design that go into the construction of commercially available turbines. There’s no telling what the state of wind energy will be in twenty, or even ten, years time. But it will certainly be exciting to find out. (Want to find out more about some cool solar products? Click this link to learn about some solar weather stations.)