The renewable energy market is continuing to go from strength to strength, with 2016 marking a series of impressive milestones versus conventional, fossil-fueled energy. Certainly, one of the most remarkable was global investment in new renewable energy infrastructure surpassing that spent on new fossil infrastructure1. This statistic reinforces how climate change policies and low-carbon initiatives have improved cost-competitiveness of renewable technologies, making them a much more affordable and accessible form of energy.
Significantly, as funding and support for renewable energy projects begins to outweigh traditional energy sources, it is necessary to ensure a continued return on this investment. This can be achieved through effective maintenance of renewable assets and management of the issues affecting them.
Whether through immersion in corrosive seawater, contact with high geothermal temperatures, or aggressive abrasion imposed by gale-force winds, the methods of harnessing greener energy are not without complications. By its very nature, capturing renewable energy involves exposure to the elements, some of which can wreak havoc on the machinery, equipment, and structures used throughout the industry. This is true for geothermal, solar, tidal, and wind power, all of which suffer from a variety of different damage mechanisms. The expansion of the renewable energy sector is certainly positive for the planet; however, maintaining the existing green assets across the globe is a challenge that confronts many energy companies.
Like the maintenance of any other industrial assets, owners and operators require cost-effective solutions that can be carried out quickly and easily yet ensure long-term results. Belzona has established itself as a worldwide provider of polymeric solutions for a variety of maintenance issues in most power generation markets, combating corrosion, erosion, and chemical attack. As a result, the transition to repair and protect renewable-energy equipment and facilities has been successful. The most progress has been made in the wind-power industry, where polymeric materials have been able to solve maintenance problems present from the base of the turbine to the tip of the blades.
Edging Ahead
From the vast investment in new renewable infrastructure, perhaps the biggest beneficiaries were offshore wind farms, which have boomed in the past 12 months. In total, capital spending commitments for this form of green energy reached a record $30 billion in 20162.
Further to these pledges, there are offshore wind-farm projects under construction in European waters that equate to 27 GW. This adds significantly to the global wind-power capacity of 433 GW logged in 20157.
Despite being one of the leading forms of renewable energy, the design of wind turbines and the environments where they operate pose a variety of problems from a maintenance perspective.
Corrosion of components and foundation damage are among some of these maintenance issues; however, the single largest problem for the wind-power industry is leading edge damage. Blade tips can revolve at up to 190 mph (300 kph) in widely fluctuating temperatures, humidity levels, and rates of UV exposure. Coupled with the damage from a variety of impact and abrasion factors, including rain, dust, ice, insects, birds, and lightning, this can cause substantial erosion of the substrate.
Evidence suggests damage to the leading edge can lower the annual energy production (AEP) of a wind turbine, with energy losses estimated between 4 percent and 20 percent if the erosion damage is severe3. This generates a reduction in aerodynamic efficiency, affecting the energy output as well as exacerbating the damage to other turbine components. Imbalance between the blades can cause wear and damage in the shaft and gearbox, in addition to putting further stresses on the tower and base. Overall, this reduces the tower’s operational life expectancy.
Alternative solutions for this problem include fillers, binders, and tapes, yet none of these will provide extensive, long-term repair and protection. In these scenarios, repairing the damaged substrate can be achieved with Belzona’s range of reconstructive composites and protective coatings. Following sanding of the damaged area and adequate surface preparation, Belzona 1121 (Super XL-Metal) can rebuild the eroded blade to original specifications, adhering extremely well to FRP substrates. As a protective layer, the molded surface can be overcoated with Belzona’s range of erosion and corrosion resistant, epoxy systems. Brush-and spray-applied, they offer a high level of durability and flexibility versus the threats of abrasion and impact.
(Courtesy: Belzona)
Rather than simply a reactive option, these solutions can be applied proactively at the OEM stage, protecting the most threatened areas before entering service. A Japanese industry-leading engineering company recently took this approach. It specified Belzona 1341 (Supermetalglide) as a protective coating for the leading edges of turbine blades during manufacture4. Over an estimated 10 years since their original installation across sites throughout the U.S., these blades have withstood the effects of erosion beyond their anticipated life expectancy.
It is not just leading-edge damage that can be rectified to improve the output and operation of wind turbines. Some of the other major issues that befall these structures involve the components in the nacelle. Protecting brake drums, sealing cables, as well as the repair of worn and damaged shafts, can be achieved with Belzona’s polymeric solutions.
Meanwhile, the integrity of the nacelle, tower, and platform can all be upheld by using seamless, weatherproof, and waterproof protective coatings, maintaining wind turbines despite the often-adverse weather conditions in their operational environments. In addition, ensuring the stable foundations of these structures is essential. Trends show blades are getting bigger as rotor diameters have steadily increased over the last 20 years in line with higher output capacities. Offshore blades in particular are estimated to reach a staggering 190 meters (623 feet) in diameter by 20305, nearly double the size of today’s blades, making firm foundations integral to keeping turbines upright. Therefore, the repair and rebuild of concrete around the base can be achieved with Belzona concrete repair systems and the surface protected with Belzona coatings.
Other Renewables
Although there is an array of maintenance solutions in place for wind turbines, this does not mean that other renewable energies are neglected in terms of their repair and protection. The stresses placed upon the likes of tidal, wave, and geothermal energy are displayed in many of the industrial environments that Belzona operates. Therefore, the solutions adept at resisting corrosion, erosion, and chemical attack will translate well into these new application scenarios.
For example, the characteristics of geothermal fluid can vary significantly, including temperature, chemistry, and non-condensable gas content (NCG), all of which can have an extremely corrosive effect on power-plant components. The negative impact on the efficiency and function of the geothermal power plant can manifest in pipes, turbine casings, heat exchangers, and tanks, all machinery and equipment which Belzona has experience at safeguarding. According to reported statistics on the state of geothermal technology, the use of corrosion resistant materials, such as protective coatings, can reduce generation costs by an estimated 0.25 cents per kWh6. When extrapolated to the global electricity generation of geothermal resources in 2015 (71 TWh)7, savings through corrosion mitigation can exceed well over $100 million, while also helping to improve the efficiency of deteriorated equipment.
Moreover, the repair and protection of turbine blades is not isolated to wind power, as this type of application has a similar role to play in the tidal-power industry. At sea level, water is 784 times denser than air, so tidal turbine rotors can be much smaller but still generate equivalent amounts of electricity. Cavitation, when there’s a pressure difference in a fluid, is prominent in this situation and can threaten the integrity of the blades, much like erosion on wind turbines. By employing a cavitation and erosion resistant solution, the in-service life of tidal turbines can be extended, protecting them against deterioration emanating from turbulent flow.
Green Intentions
With the rapidly growing presence of renewable energies in countries such as Brazil and Kenya, it is clear the world’s emerging economies are showing similar interest in the low-carbon transformation of global-energy sourcing. In fact, they are matching many of their better-equipped counterparts. This highlights the wave of support for green energy is truly growing and capturing the world’s attention.
As this sector expands, there will continue to be investments of increasing magnitude; however, it is essential these assets are maintained and remain operational, providing an effective return on investment. Polymeric repair and protective solutions already have had proven success in the power industry and have made notable impressions in the renewable energy market to date. Extensive testing and long-term involvement with industry-leading companies certainly demonstrates these systems can effectively manage the frequent issues associated with erosion, corrosion, and abrasion.
Renewable energies represent the future landscape of energy resourcing, something that Belzona aims to maintain through the development of new repair and protection systems for global renewable assets.
Acknowledgments
- Pettit, D. (2017) 2016: An historic year for renewable energy, [Online] Available at: tumblerridgenews.com/2016-an-historic-year-for-renewable-energy/. [Accessed: 1st February 2017].
- Thomas, C. (2017) Record $30 billion year for offshore wind but overall investment down. Bloomberg New Energy Finance, [Online]. Available at: about.bnef.com/blog/record-30bn-year-offshore-wind-overall-investment/. [Accessed February 1, 2017].
- Sareen, A, Sapre, C, & Selig, M. (2014) Effects of leading edge erosion on wind-turbine blade performance. Wind Energy, [Online]. 17;1531-1542. Available at: m-selig.ae.illinois.edu/pubs/SareenSapreSelig-2014-WindEnergy-Erosion.pdf. [Accessed: February 10, 2017].
- Kawano, M; Hayashi, N; Kuroiwa, T; & Nakamura, N. (2014) Wear control apparatus and wind-turbine blade monitoring system including wind-turbine blade. Mitsubishi Heavy Industries Ltd. [Patent] US 8739612 B2. Available at: bit.ly/2kph3i1 [Accessed: January 4, 2017].
- Metcalfe, J. (2016) The Future of Wind Turbines is Enormous. City Lab, [Online]. Available at: www.citylab.com/tech/2016/12/how-large-can-wind-turbines-get/509678/. [Accessed: February 15, 2017].
- Kagel, A. (2008). The State of Geothermal Technology Part II: Surface Technology. Geothermal Energy Association, [Online]. 2, 6. Available at: bit.ly/2kwQiDw [Accessed: January 4, 2017].
- REN21 (2016). Renewables 2016 Global Status Report, [Online]. Available at: www.ren21.net/wp-content/uploads/2016/10/REN21_GSR2016_FullReport_en_11.pdf. [Accessed: December 11, 2016].
