Applying bio-inspired textures to the complex three-dimensional geometries of Francis turbines presents a formidable technical hurdle for modern industrial manufacturing teams. While hydropower is recognized as one of the most reliable and established pillars of the renewable energy sector, the drive for modern innovation focuses heavily on achieving marginal efficiency gains at a microscopic level. In an industry where turbine performance is already remarkably high, researchers are turning their attention to the hydrodynamic secrets of the natural world to unlock the next generation of power generation potential. The BILASURF project, a prominent European initiative, recently concluded a series of investigations into whether the unique textures found on marine predators can be applied to massive industrial machinery. By integrating advanced laser manufacturing techniques with complex fluid mechanics, the project aims to push the boundaries of hydraulic performance through bio-inspired design. This strategy represents a significant shift from traditional mechanical upgrades toward surface-level functionalization, proving that even legacy technologies have substantial room for evolution in the current energy landscape.
Nature: The Blueprint for Modern Hydraulic Innovation
The primary inspiration for this technological leap comes from the unique and highly specialized physiology of shark skin, which has evolved over millions of years to maximize movement efficiency in water. Unlike many aquatic creatures that possess smooth exterior surfaces, sharks are covered in microscopic, aligned structures known as riblets that are designed to manage water flow with incredible precision. These tiny grooves serve a vital purpose by reducing drag and helping the animal maintain what fluid dynamics experts call attached flow along its body. By minimizing the turbulence and wall friction that typically occurs when a fluid moves across a solid surface, these structures prevent the chaotic separation of water that would otherwise slow the animal down. Replicating this biological masterpiece in a laboratory setting requires a deep understanding of how these microscopic dimensions interact with moving fluids at varying velocities, a task that has become increasingly feasible through modern computational modeling and high-resolution imaging.
When these shark-inspired riblets are replicated on the blades and vanes of a heavy-duty hydropower turbine, they serve a vital operational function that transcends simple aesthetics. By reducing the energy losses caused by friction, these structures allow water to pass more smoothly through the turbine runner, ensuring that more kinetic energy is converted into mechanical work. Even a fractional increase in efficiency is considered highly valuable in the global energy sector, as it can result in massive cumulative energy gains over the several decades that a large dam remains in operational service. This efficiency boost is particularly critical for maximizing the output of existing infrastructure without requiring the construction of new, environmentally disruptive facilities. As the world seeks to optimize every kilowatt of renewable energy, the ability to mimic the low-drag capabilities of apex predators offers a sophisticated path forward. This approach aligns with the broader movement toward biomimetics, where engineering challenges are solved by observing how biological systems have already mastered similar physics.
Laser Functionalization: Bridging Theory and Production
Developing a method to engrave these biological patterns onto massive, three-dimensional industrial components required a multi-disciplinary effort that spanned several specialized fields. The BILASURF consortium brought together ten European partners, including research institutes such as Ceit and Fraunhofer IWU, alongside industrial experts from companies like GLOBAL Hydro and AIMEN. This collaborative technology value chain was designed to bridge the gap between theoretical fluid dynamics and the practical realities of heavy manufacturing, ensuring that every stage of the process—from the initial design of the riblet structures to final validation—was handled by industry leaders. A significant hurdle in this process was moving away from traditional coatings, which often peel or fail under the extreme pressure and friction found inside a high-head turbine environment. Instead, the project focused on laser functionalization, a process that uses high-rate lasers to engrave the required riblet geometry directly into the metal of the turbine components for a permanent finish.
This technique is particularly difficult when applied to the complex, curved geometries of Francis turbines, which feature intricate shapes that are notoriously hard to reach with standard manufacturing tools. While researchers successfully textured the stationary guide vanes, the intricate nature of the rotating runner meant that further development is still needed to treat the entire system within a single production cycle. The use of in-line process monitoring and specialized laser micro-cladding allowed for a high degree of precision, but the time required to complete these textures remains a point of intense research. As of 2026, the focus has shifted toward increasing the speed of these laser systems to make them more compatible with the fast-paced requirements of industrial assembly lines. By perfecting the application of these textures on three-dimensional surfaces, manufacturers can move closer to a future where high-performance surfaces are a standard feature rather than an experimental luxury. The integration of these advanced manufacturing methods is essential for scaling bio-inspired designs to a global level.
Empirical Validation: Testing at the SuperGrid Institute
To prove the efficacy of these bio-inspired surfaces, the SuperGrid Institute utilized a reduced-scale Francis turbine model for a series of rigorous performance tests. Using a specialized hydraulic test rig that complies with international IEC 60193 standards, researchers simulated real-world conditions by precisely controlling flow rates, pressure, and hydraulic head. The team mapped performance across various operating conditions, creating what are known as efficiency hill charts to compare the laser-textured components against standard smooth surfaces used in traditional turbines. These charts provided a comprehensive visual representation of how the turbine responded to different flow environments, allowing the researchers to pinpoint exactly where the riblet technology provided the most benefit. The results indicated that the textured surfaces maintained their integrity under high-stress conditions, providing a stable platform for further testing. This empirical approach ensured that the theoretical gains predicted by computer simulations could actually be realized in a physical hydraulic system.
Beyond full-scale model testing, the researchers conducted isolated hydrofoil profiling in low-flow water tunnels to gain a clearer understanding of the physics at play. This allowed for the precise measurement of lift and drag without the interference of other turbine parts, such as the casing or the draft tube. These tests provided clear evidence that the textured profiles could successfully mitigate flow separation, which is a major source of energy loss in hydraulic machines. Importantly, the experiments also closely monitored cavitation—the damaging collapse of vapor bubbles that can erode metal surfaces—and found that the riblets did not increase the risk of surface damage. This finding was a major milestone for the project, as it confirmed the technology’s safety and durability for long-term use in demanding environments. By proving that the textures do not negatively impact the lifespan of the turbine, the research team cleared one of the biggest regulatory hurdles for the adoption of bio-inspired surfaces in the commercial hydropower sector.
The Transposition Challenge: From Laboratory to Industrial Scale
One of the most critical discoveries of the project involved the transposition of results from the laboratory to the field, highlighting a common struggle in hydraulic engineering. Because laboratory models are significantly smaller than the massive turbines installed at major dams, researchers found that the effects of riblets do not scale in a simple, linear fashion. The hydraulic response changes based on the size and velocity of the component, meaning that a riblet geometry that works perfectly on a small model might not provide the same benefits on a full-sized prototype. This phenomenon suggests that the microscopic dimensions of the texture must be specifically tailored to the unique dimensions and operating speed of each individual turbine rather than being applied as a universal, one-size-fits-all solution. Understanding these scaling laws is vital for engineers who wish to move this technology from the research phase into widespread industrial application across different types of power plants.
Testing comparing different scale factors revealed that the hydraulic response was highly sensitive to the orientation and size of the riblets relative to the water flow. This directional dependency means that if the water hits the texture at the wrong angle, the benefits can be lost or even reversed. Consequently, the precision of the laser engraving process becomes even more important, as every micrometer must be aligned perfectly with the predicted flow of water. This insight has led to a more nuanced approach to turbine design, where the surface texture is treated as an integral part of the hydraulic profile rather than an afterthought. As the industry moves forward, the development of international standards for textured surfaces will be necessary to ensure that these enhancements are applied consistently and safely. The lessons learned from the BILASURF project have laid the groundwork for these future standards, providing a clear roadmap for how to manage the complexities of scaling microscopic biological designs for use in the world’s largest energy machines.
Strategic Integration: Future Deployment of Bio-Inspired Textures
The BILASURF project successfully established a credible research path by demonstrating that bio-inspired surfaces can measurably influence hydraulic behavior without compromising the structural integrity of the machine. Researchers proved that the marriage of biomimetics and laser technology offers a powerful tool for the future of renewable energy optimization, even if the road to full commercialization requires more work. During the testing phases, the team identified that the highest potential for efficiency gains lies in texturing the turbine runner, which remains the most difficult part to treat due to its complex rotation and geometry. The project successfully navigated the initial risks associated with cavitation and material durability, showing that these microscopic structures can survive the harsh conditions inside a functioning turbine. These results have paved the way for a new era of turbine design where the focus shifts from the macro-geometry of the blades to the micro-geometry of the surface itself, creating a multi-layered approach to energy efficiency.
To move this technology into the mainstream, the next steps must focus on improving the economic feasibility and manufacturing speed of laser functionalization. Industry leaders should prioritize the development of automated laser systems that can handle larger components with minimal manual intervention, reducing the overall cost of the upgrade. Furthermore, additional field studies are required to determine how these microscopic textures perform in run-of-river plants where the water is often laden with abrasive sediment that could potentially wear down the riblets over time. Standardizing the laser engraving process across different turbine manufacturers will be essential for creating a competitive market for these high-efficiency components. By continuing to refine the application process and tailoring riblet designs to specific site conditions, the hydropower industry can squeeze every possible drop of energy out of flowing water. The transition toward these optimized surfaces represents a logical evolution for a sector that remains vital to the global shift away from fossil fuels and toward a more sustainable, bio-inspired future.
