What Are The Steps To Make Energy From Wind?
Wind energy is renewable energy generated from the wind, or the air flow that occurs naturally due to atmospheric circulation. Wind turbines convert the kinetic energy in wind into mechanical power, which is then converted into electricity through a generator.
People have been harnessing wind energy for thousands of years. The earliest known use was in sailing ships on rivers and seas. Simple windmills that converted wind energy into mechanical energy appeared more than 2000 years ago. Electricity-generating wind turbines were pioneered in the late 19th century. However, wind power remained a niche energy source until the 1970s oil crisis spurred renewed interest.
Today, wind power is one of the fastest-growing renewable energy sources globally. As concerns about climate change and energy security rise, wind energy offers a sustainable alternative to fossil fuels. Wind turbines produce no air or water pollution during operation, and have among the lowest carbon emissions per unit of electricity generation. Expanding wind power can help nations meet emissions reduction targets under international agreements like the Paris Climate Accord.
How Wind Turbines Work
Wind turbines convert kinetic energy from the wind into mechanical power. This is then transformed into electricity that can be used for residential, commercial, and industrial applications. There are several key components that allow wind turbines to harness energy from the wind.
Parts of a Wind Turbine
A wind turbine is comprised of three main parts:
- A tower
- Nacelle
- Rotor blades
The tower is a tall structure made of tubular steel, concrete, or steel lattice. It can range from about 30 meters up to 140 meters tall. The nacelle sits atop the tower and contains the gearbox, low and high speed shafts, generator, controller, and brake. The blades are attached to the nacelle and spin when wind blows past them.
How Blades Capture Wind Energy
The blades are made of fiberglass-reinforced polyester or wood-epoxy. Their aerodynamic shape allows them to capture the kinetic energy of the wind. When wind blows past the blades, lift is generated – much like with an airplane wing. The rotor spins as a result of this lift force. The rotor is connected to the main shaft, which spins a generator to produce electricity.
Transfer of Mechanical Power
The rotational motion caused by the spinning blades is converted into electrical energy inside the nacelle. First, the low-speed shaft connected to the rotor transmits power to the gearbox. The gearbox has planetary gears that increase the rotational speed to that required by the generator. The high-speed shaft then delivers this mechanical power to turn the generator. The generator uses magnetic fields to convert the rotational energy into electrical energy. Cables inside the tower transmit the electricity down to a transformer, where voltage is increased and the power is sent to the electric grid.
Site Selection
Selecting the right site is crucial for maximizing the energy output and return on investment of a wind farm. There are several key factors to consider when choosing a location:
Wind Resource
The wind speed and consistency at the site is the most important factor. Areas with average annual wind speeds of at least 6 meters per second at turbine hub height are generally considered economically viable. Developers use wind resource maps and on-site wind studies to identify areas with the highest wind energy potential.
Access to Transmission
The site needs to be near existing electricity transmission infrastructure like power lines and substations to transport the energy to the grid. New transmission lines can be costly to build.
Available Land
Modern commercial-scale wind turbines typically require about 1 acre of land per megawatt of generating capacity. The site needs sufficient available land with the right topography and soil conditions.
Permitting and Local Regulations
The site must meet all zoning and permitting requirements. Local community support is also ideal. Proximity to airports, wildlife areas, or low frequency military radar may pose restrictions.
Placement of Turbines
Within the site, turbines should be spaced 3-10 rotor diameters apart (150-500m for modern turbines) to avoid wake effects from upstream turbines. Topography, land shape, and prevailing winds determine optimal placement.
Permits and Regulations
Developing a utility-scale wind farm requires obtaining permits and approvals at the local, state, and federal levels. Significant planning goes into siting, permits, regulations, and environmental impact studies. The process involves multiple government agencies.
Local permits relate to zoning, building, roads, drainage, and noise regulations. Counties or townships often require special use permits for commercial wind developments. There may be restrictions on turbine height, sound levels, setbacks from property lines, and flicker effects.
At the state level, permits are required for impacts on wildlife, water use, utility interconnections, and transmission lines. States have different environmental regulations and siting requirements. Environmental impact studies assess effects on wildlife, habitat, viewsheds, and more. States also handle permit applications for interconnecting to the power grid.
Federal agencies play a role in permitting and environmental regulations too. The Federal Aviation Administration (FAA) reviews proposed turbines for airplane safety. The U.S. Fish and Wildlife Service evaluates impacts on birds, bats, and endangered species. Other agencies like the Army Corps of Engineers may be involved with wetlands permits and transmission lines crossing federal lands.
Transmission Infrastructure
Once the wind turbines are built, the generated electricity needs to be transported to the electrical grid where it can be distributed to homes and businesses. This requires building transmission infrastructure to get the power from the wind farm to the grid. There are two main components involved in connecting wind turbines to the grid:
Connecting Turbines to Grid
Within the wind farm itself, distribution cables are laid in trenches to connect the individual wind turbines to each other and to one or more substations at the wind farm. This allows the power from all the turbines to be collected at the substations before being transported to the grid. The cables are buried underground for protection from weather and other hazards.
Transformers and Substations
Step-up transformers are used at the substations to increase the electricity to high voltage levels for efficient transmission over long distances on the transmission lines. The transmission lines carry the power to a substation owned by the grid operator. Here, step-down transformers reduce the voltage to levels appropriate for distribution on the grid. Safety equipment like circuit breakers and disconnect switches are also important at substations to protect the grid infrastructure.
Construction
Transporting the massive wind turbine components from the manufacturing facility to the wind farm site can be a major logistical challenge. The blades alone are often longer than 200 feet, so specialized trucks and routes must be mapped out ahead of time.
Once the components make it onsite, the construction process begins by installing the wind turbine foundations. These are made of reinforced concrete and anchor the tower to the ground, often extending 10-30 feet below the surface. Digging these deep foundations requires heavy excavation equipment.
Next, immense cranes are brought onsite to hoist the tower sections into place and bolt them together. The nacelle, which contains the generator and gearbox, is then lifted and attached atop the tower, followed by installing the rotor and blades one-by-one.
Safety is paramount during the turbine assembly, as even a small mistake could be catastrophic when handling such large and heavy components at great heights. Strict protocols are followed to prevent accidents.
After assembly, the turbines are thoroughly tested to ensure proper operation before being commissioned and synchronized to the electric grid.
Operation and Maintenance
Once a wind energy project is constructed and operational, ongoing operation and maintenance (O&M) is crucial to ensuring the wind farm continues generating clean electricity reliably over its lifetime of 20-25 years. Effective O&M involves monitoring performance, conducting preventative maintenance, and repairing components as needed.
Monitoring performance is essential for maximizing a wind farm’s productivity. Detailed performance monitoring provides critical data to identify any drops in production or availability of individual turbines. Monitoring typically tracks factors like wind speeds, turbine operating status, generator output, temperature of components, vibrations, etc. This data helps pinpoint developing issues requiring maintenance.
Preventative maintenance involves regularly inspecting and servicing equipment to minimize unplanned downtime. This includes activities like lubricating parts, tightening bolts, replacing worn components before failure, and checking for leaks, cracks or corrosion. Service technicians use rigging and climbing equipment to access turbine internals and perform hands-on preventative maintenance per the manufacturer’s recommendations.
Despite best preventative efforts, repairs will inevitably be needed over a wind farm’s lifetime. Technicians troubleshoot issues using SCADA performance data, inspections, and diagnostics. Common repairs include fixing hydraulic and electrical control systems, replacing damaged blades or gearbox parts, servicing generators and bearings, and repairing faults in the yaw system that orients the turbine into the wind. Having replacement parts ready in inventory minimizes repair time.
Power Purchase Agreements
An important consideration for any wind energy project is negotiating a power purchase agreement (PPA) to sell the electricity generated. A PPA is a legal contract between the wind farm owner and a utility company or other buyer, that establishes the terms for the sale of electricity produced.
The PPA will specify details like the duration of the agreement (typically 15-25 years), the rate per kilowatt-hour the buyer will pay, and the expected delivery schedule for the electricity. Securing a PPA with fair rates and terms is essential for the financial viability of a wind energy project.
Utility companies are often the primary buyers for wind farm electricity. The rates they offer in PPAs are influenced by their state’s renewable portfolio standards, which require utilities to source a certain percentage of their electricity from renewable sources. Wind farm owners will negotiate to get the best possible rates in the PPA based on prevailing wholesale electricity prices and incentives.
The PPA acts as a long-term revenue guarantee for the wind farm. While wholesale electricity prices fluctuate over time, the PPA locks in a fixed rate over its lengthy term. This provides stability and helps secure the financing needed to build the wind project. Overall, successfully negotiating PPAs is a key step in profitably selling the clean electricity produced by wind energy projects.
Financial Incentives
There are several financial incentives available to help offset the costs of developing wind energy projects in the United States.
Tax Credits
The federal renewable electricity production tax credit (PTC) provides wind energy project owners with a per-kilowatt-hour tax credit for the first 10 years of a renewable energy facility’s operation. This tax credit has helped drive substantial growth in the U.S. wind industry.
Grants
The U.S. Department of Energy and U.S. Department of Agriculture periodically offer grants to support wind energy research, development, and infrastructure. These grants help fund innovation and provide financing for rural wind projects.
Renewable Energy Certificates
Renewable energy certificates (RECs) provide wind farm owners with additional revenue for the renewable attributes of their generation. RECs can be sold separately from the power itself to utilities and other buyers interested in using renewable energy to meet regulatory requirements or sustainability goals.
Future Outlook
The future looks bright for wind energy, with several key trends driving growth:
Technology improvements
– New turbine designs, larger rotors, and taller towers continue to increase capacity factors and lower costs.
– Advances in blade design, smart sensors, and robotics will boost efficiency and reliability.
– Floating offshore foundations will unlock deeper water sites with steadier winds.
Offshore wind potential
– The U.S. has 2,000+ gigawatts of offshore wind capacity within 50 miles of shore.
– Falling costs make offshore competitive with other energy sources.
– States like New Jersey aim for 7.5 gigawatts of offshore wind by 2035.
Projections and goals
– The DOE projects wind will supply 20% of U.S. electricity by 2030 and 35% by 2050.
– Many states and corporations have 100% renewable energy commitments.
– With supportive policies, wind can be a major player in decarbonizing the power sector.
