The potential for wind energy is massive. Although wind energy currently represents only about five percent of the world’s total electricity, many experts predict it could easily produce at least one-fourth to one-third of the world’s total production by 2050.
Much of the expected growth is projected to come from offshore wind farms. In the United States, northern California has been identified as the site for America’s first floating offshore wind farm. In addition, states like New York, New Jersey and Massachusetts already are making major commitments to developing future offshore wind farms.
The benefits of offshore wind farms include:
they don’t take up valuable land space
offshore wind power is typically more constant and less turbulent than onshore wind
the hauling of components out to sea is relatively easy to manage
Read part 2 of our white paper- 2021 Power Generation and Renewable Energy Trends, to explore renewable energy technology trends, both established and newer technologies including wind, solar, biogas, and hydroelectric.
Offshore wind farm challenges include aesthetic issues if the wind farms are located near the shore. If they are farther out, the water is often too deep to build a traditional tower, which means a less-stable floating structure must be built.
The floating platforms are exposed to harsher conditions, resulting in increased vibration, fatigue and heavy loads on the structure. As researchers continue to evaluate possible innovations that result in greater reliability and less downtime, they are looking to the offshore oil and gas industry for solutions, as many of the same mechanical issues are faced in those operations.
Previous innovations have focused on improving the design of offshore turbines, optimizing the blade shapes, identifying more robust, lighter-weight materials and adding intelligent control systems. The search continues for lighter-weight materials that are flexible but still strong. In typical offshore turbines, the entire system is constantly flexing, so components must be able to withstand continuous flexing without prematurely failing.
The key to maximizing the potential of wind energy is building taller wind turbines with longer blades. Already the largest flexible rotating machine in the world, today’s wind turbine blades exceed 80 meters (262 feet) in length on towers that rise 100 meters (328 feet) meters and even 200 meters (656 feet).
To access faster, more powerful winds, however, it is estimated that the towers will need to reach heights above 300 meters (984 feet). That presents major challenges since, at those heights, the turbines would straddle two layers of the atmosphere and be subjected to varying atmospheric forces. Researchers need to better understand the dynamics of wind at these higher elevations. While skyscrapers exceed these heights, they are not moving, so the wind is less of a factor in their design and maintenance.
More powerful offshore turbines are coming, as manufacturers continue pushing the capacity of offshore wind farms. Wind turbines are also getting smarter with digitally connected sensors and artificial intelligence-driven (AI) software that anticipates and reacts to changing conditions, predicts component longevity and communicates with remote data centers. The enhanced use of AI is increasingly automating operations, boosting productivity and cost savings.
Of course, turbines are only as good and reliable as their individual parts. With the tremendous stress on the turbines (especially as they are being built taller and farther out at sea), mechanical failures and overheating are key concerns.
Parker manufactures several high-performance, durable components for wind turbines, including bladders, pumps, diaphragms, pistons and valves, sealants, power conversion systems, integrated lube oil filtration systems and compact blade activation systems. Learn more about these wind turbine products and solutions.
Wind turbines are built with emergency pitch-control systems to protect them from damage during excessive wind speeds or grid power loss. Such systems are vital to the ongoing safe and reliable operation of the turbines, as they shift the turbine’s blades out of the wind and slow down the rotor from spinning out of control. Some industry experts estimate that pitch control failures account for nearly one-quarter of all downtime in wind turbines.
Parker has responded to this problem through continuous improvement in its pitch control valves, ensuring they can withstand heavy vibration and shock, as well as extreme temperatures. The D1FC and D3FC direct operated proportional DC valves with position feedback represent major breakthroughs. They feature anti-shock mounting technology that allows them to withstand harsh operating environments and are well sealed to protect against dirt and moisture.
Pitch control failures also can be the result of problems with the battery, including voltage faults and degraded performance in hot or cold weather. A newer, promising alternative to battery-based systems is ultracapacitor-based energy storage for the pitch system. Ultracapacitors are high-powered devices that store charges electrostatically.
Lead-based batteries, in contrast, operate electrochemically. An inherent disadvantage affecting the reliability of batteries is the nature of their chemical process. Ultracapacitors, on the other hand, are touted to offer greater efficiency and reliability in emergency pitch controls and require no scheduled maintenance for at least 10 years. This translates into considerable savings in maintenance time and costs.
As wind turbine blades continue to get longer to maximize energy production, the bearings turning the blades are subjected to increased stress. A challenge is that bearings need to be compact in design to help reduce overall component size, weight and manufacturing costs. Newer tapered roller bearings have recently demonstrated a highly desirable performance compared to conventional, spherical roller bearings. The tapered bearings are smaller in size with their rings and rollers tapered in the shape of truncated cones to simultaneously support axial and radial loads.
The tapered shape offers increased power density which reduces the overall cost of energy and can bear both thrust and radial loads. This is critical in ensuring consistent performance despite harsh conditions and unpredictable changes in wind speed and direction.
Cable faults are more likely with offshore wind farms because the subsea equipment is deployed from a vessel or retrieved from the water which places extreme tension on the attached subsea cables.
Underwater helical cable terminations have recently been shown to prevent fault because they disperse the stress that would have occurred at a localized point on the cable over the entire length of the cable. An added advantage of the helical cable terminations is that they can be installed anywhere along the length of the cable without access to the cable end. In addition, they require no tools or cable preparation.
In response to the growing global demand for more sustainable energy options, research is underway to further reduce the environmental impact of wind power and increase its consistency. Two of the larger focus areas include the use of floating solar panels and green hydrogen. In both cases, the goal is to store power to generate extra electricity during periods of high demand.
Interest in green hydrogen is skyrocketing, not just for wind farms, but also for use in the oil and gas industry. A green hydrogen electrolysis system deploys an electric current to “split” hydrogen gas from the water. Such a system could run during periods of low demand, using excess wind power, solar power, or both. One challenge is that electrolysis typically requires purified water, which means more energy is needed to run the system. Research is ongoing for solutions that would minimize energy demand for this process.
The potential for wind energy appears unlimited. However, the industry will need additional innovations to solve current challenges regarding reliability, productivity, and sustainability.
To learn more about wind energy, read our 2021 Power Generation and Renewable Energy Trends White Paper – Part 2.
This article was contributed by the Hydraulics and Energy Teams.
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