What Is The Definition Of Wind Energy National Geographic?

Wind energy refers to the process of harnessing the natural power of wind to generate electricity. Wind turbines convert the kinetic energy in wind into mechanical power which is then converted into electricity. Wind power is considered a renewable energy source since wind will continually replenish itself. The use of wind energy to generate electricity has expanded rapidly in recent decades as more countries have moved to diversify their energy mix and reduce reliance on fossil fuels.

This article provides an overview of wind power, how it works, the different types of wind turbines, and the current use and future potential of wind energy. The goal is to give readers a comprehensive understanding of this renewable energy source that is gaining prominence worldwide. We will explore the environmental and economic benefits that make wind an appealing part of a clean energy future as well as some of the challenges that need to be addressed for wider adoption.

Table of Contents

History

Humans have been harnessing the power of the wind for thousands of years. The earliest known use of wind energy was in sailing boats on the Nile River as early as 5,000 BCE. Simple windmills were used in Persia (now Iran) as early as 200 BCE to grind grain. Vertical axis windmills may have been used in China as early as the 1st century CE.

In the 7th century CE, vertical axis windmills were introduced to Europe and became an important source of energy. Dutch windmills, an improved horizontal axis design, emerged in the late Middle Ages. Windmills were an essential technology that allowed the mass production of flour, lumber, textiles and other industrial products.

Throughout the 19th and 20th centuries, engineers continued to refine windmill technologies. Key innovations included steel blades (early 1850s), AC electric generators (late 1800s), regulating mechanisms to control blade speed (1890s-1920s), aerodynamic blade shapes (early 1900s), and grid-connected wind generators (1940s-1950s).

The oil crisis of 1973 drove new interest and investment in renewable energy, including wind power. The first commercial wind farms emerged in the 1980s. Since then, advancements in materials, aerodynamics, electronics and manufacturing have led to larger, more efficient and more reliable turbines.

How Wind Turbines Work

Wind turbines convert wind’s kinetic energy into electricity. The key components involved in this process are:

Blades – Most modern wind turbines have three blades that face into the wind. Blades are typically made of composite materials such as fiberglass.
Rotor – The blades and hub together form the rotor. This component catches the wind and spins the shaft.

Nacelle – The nacelle sits atop the tower and contains the essential mechanical components such as the drive train, gearbox, generator, controller, and brake.
Drive Train – The drive train includes the rotor shaft, gear box, coupling, and generator.
Gearbox – Gears connect the low-speed shaft to the high-speed shaft and increase rotations.

Generator – The generator uses electromagnetic induction to convert the rotational energy into electrical energy.
Anemometer – Measures wind speed and transmits wind speed data to the controller.
Wind Vane – Detects direction of the wind.

Controller – The controller starts up the machine at wind speeds of about 8 to 16 mph.
Brake – Brakes can be applied mechanically, electrically, or hydraulically to stop the rotor in emergencies.
Tower – Towers are made from tubular steel or concrete. Taller towers enable turbines to capture more energy.

When the wind blows, the blades capture the wind’s kinetic energy and rotate the rotor. The rotor connects to the main shaft, which spins a generator to convert the rotational energy into electrical energy. The electricity is then fed into a transformer and delivered to the grid.

Types of Wind Turbines

There are two main types of wind turbines: horizontal axis and vertical axis. Horizontal axis wind turbines are the most common. They have blades that spin perpendicular to the ground, parallel to the wind direction. Vertical axis turbines have blades that go from top to bottom, spinning vertically.

Horizontal axis wind turbines come in a variety of sizes, with small models generating just a few kilowatts while large commercial scale turbines can generate over 5 megawatts. The size of the turbine determines how much power it can generate. Larger blades can capture more wind energy. Many turbines have 3 blades, but some have 2 or more. The design of the blades can vary as well, with some being rigid while others are flexible.

Vertical axis wind turbines have some advantages such as generating power independent of wind direction and placing machinery at ground level for easier maintenance. However, they tend to be less efficient than horizontal axis turbines. Vertical axis turbines come in two main types: Darrieus and Savonius. The Darrieus design looks like an eggbeater with curved blades. The Savonius turbine has scoops or cups on the blades to catch the wind.

In addition to the axis orientation and blade design, wind turbines can have different hub heights and different ways of integrating power generation components inside the nacelle at the top of the tower. Larger turbines are able to take advantage of faster wind speeds at higher hub heights.

Wind Energy Production

Wind energy capacity worldwide has grown rapidly in recent years. Total installed wind power capacity is now over 650 gigawatts (GW), with over 60 GW added in 2018 alone. Wind power currently meets around 5% of global electricity demand.

China has led the world in both wind power capacity and new wind installations for over a decade. At the end of 2018, China had over 200 GW of wind power capacity, accounting for over one-third of the global total. The United States ranks second in terms of capacity at nearly 100 GW. Germany, India and Spain round out the top 5 countries for total installed wind power.

The global offshore wind market has also grown quickly, led by the UK, Germany, China and other European countries. Total offshore wind capacity reached nearly 23 GW by the end of 2018. While onshore wind has slowed in some markets like China and the US recently, offshore wind is expected to drive much of the near-term growth.

The Global Wind Energy Council (GWEC) projects that global wind power installations will continue to grow rapidly. Total wind power capacity could reach over 2,000 GW by 2030, under current expectations.

Benefits

Wind energy provides numerous important benefits that make it an attractive renewable energy source.

Clean and Renewable

Wind turbines produce electricity without emitting greenhouse gases or other air pollutants. Wind is an abundant, renewable resource that does not run out like fossil fuels. Harnessing wind to generate electricity does not create any toxic byproducts. This makes wind energy one of the cleanest energy sources available.

Reduced Greenhouse Gas Emissions

Using wind energy to produce electricity significantly reduces greenhouse gas emissions compared to fossil fuel-based energy. According to the U.S. Department of Energy, generating enough wind energy to power over 19 million homes in 2020 reduced CO2 emissions by over 42 million metric tons. As wind energy continues to grow as part of the nation’s energy mix, it will play an important role in reducing greenhouse gas emissions and mitigating climate change.

Economic Benefits

Wind energy provides economic advantages at both the local and national levels. Wind farm development creates jobs and generates tax revenue in rural communities. Wind projects also attract private investment in new infrastructure and generate lease payments for landowners. At a national level, wind energy reduces dependence on fossil fuel imports, keeping energy expenditures within the U.S. economy. The Department of Energy found that wind projects completed in 2020 created over 8,000 direct jobs across 40 states.

Challenges

While wind energy offers many benefits, it also comes with some significant challenges that need to be addressed.

Intermittency

One of the biggest challenges with wind energy is its intermittent nature. The wind doesn’t blow consistently throughout the day and generation output can vary a lot in a short period of time. This makes wind power more difficult to integrate into the grid compared to more stable sources like fossil fuels or nuclear power.

Land Use Constraints

Modern wind turbines take up a lot of physical space and have specific geographical requirements, like being sited in windy, open areas. Their large size and spacing requirements means wind farms can’t simply be built anywhere. Finding suitable locations with good wind resources that don’t conflict with other land uses can be difficult.

Impacts on Wildlife

Wind turbines can also negatively impact birds and bats that live and migrate through areas where wind farms are located. The spinning blades can strike flying wildlife, causing injury and death. There are ongoing efforts to assess and mitigate the threats that wind turbines may pose to wildlife populations.

Offshore Wind Farms

Offshore wind farms are large collections of wind turbines installed in bodies of water, usually oceans, lakes, or seas. They provide a number of advantages over their onshore counterparts.

One of the biggest advantages of offshore wind is their access to stronger, more consistent winds. Winds tend to blow harder and more steadily over open water compared to over land. This allows offshore wind turbines to generate more renewable electricity than onshore wind turbines.

Being located in the water also gives offshore wind farms more space to spread out larger numbers of wind turbines. On land, available space is often limited by geography, land ownership, or existing infrastructure. The ocean provides a vast open area for wind project development.

Placing wind turbines offshore also reduces concerns over noise pollution, visual impacts, and some environmental effects like habitat disruption. Although offshore wind farms impact marine environments and habitats, they avoid many negative impacts associated with onshore wind projects.

Some of the major existing offshore wind projects include:

The London Array in the UK, currently the largest offshore wind farm in the world at 630 MW.
The Greater Gabbard farm off the UK east coast, generating 504 MW.

Denmark’s Horns Rev 2 project in the North Sea, at 209 MW.
China’s Rudong Offshore Wind Farm, the first large-scale offshore wind project in Asia.

Many more large offshore wind projects are in development or under construction around the world. The global offshore wind market is projected to grow rapidly in the coming decades. Costs are decreasing as technology improves, infrastructure develops, and project experience grows. Offshore wind capacity could expand more than tenfold by 2040 based on current trends and targets.

Small Scale Wind Turbines

In recent years, small scale wind turbines have become increasingly popular for homeowners and businesses looking to utilize wind power on a local level. These are smaller turbines designed to directly provide electricity to a home, farm, or small business.

Small wind turbines are available in sizes ranging from less than 1 kW to over 100 kW. The smaller turbines (under 10 kW) are typically used for battery charging or to power off-grid homes. Larger small wind turbines can be tied into the grid to offset electricity usage and provide net metering credits.

For homes and businesses with enough wind resource, small wind turbines can provide clean and renewable power generation. They can lower or even eliminate electricity bills when sized and sited properly. Installing a small turbine also decreases reliance on utility providers.

However, small wind turbines do have some limitations. They can be expensive upfront and may have a long return on investment period. Turbines require adequate wind speeds of at least 10 mph for power production. Placement is also critical – turbines need to be sited in wide open areas without obstructions that can block wind. Ongoing maintenance costs can also be an issue.

Overall, small wind turbines provide a sustainable way for homeowners and businesses to utilize the power of wind. With proper siting and realistic expectations, they can be an effective local energy solution.

Future of Wind Power

As the world looks to transition away from fossil fuels and reduce greenhouse gas emissions, wind power is poised to see tremendous growth in the coming decades. Projections indicate that wind energy could supply up to 20% of global electricity by 2030 and potentially 50% by 2050. This will require continued innovation in wind turbine technology and increased adoption worldwide.

Several trends point to a bright future for wind power. Turbines are becoming more efficient, productive, and cost-effective through advances in materials, blade design, and height. New floating offshore wind farms allow access to the immense wind resources over deep seas. Emerging markets like Africa, Asia, and Latin America are investing more in wind energy. With the costs declining and competitiveness increasing, wind has the potential to play a major role in the global energy transition.

However, realizing the full potential of wind energy will require overcoming lingering challenges. These include further improving grid integration, storage, and transmission infrastructure to accommodate variable wind patterns. There is also a need to streamline permitting and financing processes. If these hurdles can be addressed, projections indicate wind power could provide over a third of the world’s electricity by 2050. With the right policies, investments, and technologies, wind can become a centerpiece in building a clean energy future.