King's College London

The Department of Engineering’s Dr Yabin Liu has been awarded a €1.5 million Starting Grant from the European Research Council to transform the efficiency, cost and scale of wind and tidal power.

By creating structures only centimetres in size, Dr Liu hopes to break apart the large ‘tornado-like’ vortices that have long plagued the turbines of wind farms.

When a turbine or propellor spins, whether that be in air or water, the pressure difference across each blade generates a small vortex at its tip. While initially small, over a short period of time these vortexes grow significantly to the scale of the turbine diameter, often hundreds of meters across, moving in the direction that the wind is blowing.

In the case of a wind farm, the vortices generated by one turbine can travel and reach the turbines behind it, disrupting the incoming airflow and cutting its power generation by up to 46%.

As this effect can scale across wind farms, this prevents efficient grouping of turbines, causing engineers to design expensive whole-scale solutions to this problem – such as adjusting how individual turbines operate or simply taking up a far larger area to mitigate the problem.

Both solutions pose significant financial cost, whether through the deployment of costly technology, or the inefficient use of available land, where a greater number of turbines in a smaller space would otherwise generate more cost-effective power.

Over the course of five years, Dr Liu alongside a team of postdoctoral researchers and PhD students will develop a small add-on device that can be added onto the tip of a turbine to disrupt the formation of vortexes before they even start.

Dr Liu said, "Recent climate events in places like Europe have shown the pressing need to efficiently scale up renewable power generation. For wind, you need to be able to effectively and tightly group turbines together and cut their overall costs of operation – and we believe we’ll soon have the tools to do that through a better understanding of fundamental vortex dynamics.

"By intervening early, at this very small scale, we can completely disrupt the coherency of vortexes before they begin to cause a problem – at a much cheaper cost than redesigning the entire way a wind farm works. Ours is a completely cross-scale vortex control approach that can be applied across any rotor system."

As vortex formation is consistent across rotors in both the air and water, the add-on the team propose can also be applied to tidal power generation, leading to more energy efficient and resilient energy generation beyond wind.

In addition to similar issues that vortexes in water pose to tidal energy generation, tidal turbines also suffer a problem that their wind counterparts do not. When a turbine or propellor rotates quickly in water, the high-speed flow around the blade tips can create areas of very low pressure, causing vapour bubbles to form.

These bubbles can then collapse violently, releasing a large amount of pressure which over time damages the rotor blades, leading to costly maintenance or replacement.

This process can also be very noisy, meaning that a ship’s propellor systems can be disruptive to marine life and cause significant habitat loss in busy shipping lanes.

Through a universal approach that disrupts vortexes at their smallest scale, the team hope to change the fundamental impact of rotor systems across all environments, leading to more efficient, resilient and eco-friendly power generation.