Startup Develops ‘Helical’ Generator That Could Harness Largely Untapped Wave Energy — Here’s How It Works

According to an article in Interesting Engineering magazine, a London-based startup called Spiralis Energy has proposed using its “screw” tidal power generator in the state of Alderney, an island in the English Channel that floats between France and England.

This is in response to an appeal by the local energy task force, which has invited proposals from companies working with tidal energy. This is the process of harnessing energy from the natural rise and fall of ocean tides caused by the gravitational interaction between the Earth, the Sun and the Moon.

Bill Abel, leader of the Energy Working Group, explained in a press release: “We have the potential to produce renewable energy from solar, wind, tidal and wave resources, and now, in addition to developing solar and wind power generation options, we are opening up the opportunities offered by our extensive tidal resources.”

The group estimates the tidal potential in the area is enough to generate up to 3 gigawatts. This will help free the island from dependence on dirty fuel imports, reduce its carbon footprint and expand its clean energy infrastructure.

According to a report by Offshore Energy, the study found that tidal power could supply around 11.5 gigawatts of energy to the UK grid, which is around 11% of electricity demand.

Spiralis has already tested a prototype and is about to install two of its 66-foot Axial Skelter generators off the coast of Alderney. These will be the first trials, mainly to measure tidal flow in the region during the colder winter months, the report details.

Their technology is a riff on the Archimedes screw concept, although it works in reverse, generating power as water flows through the spiral and spins the device. What makes their technology unique is the addition of aerodynamic sections inside the screws, which help increase torque and therefore power output. So far, the company says it has achieved 500 kilowatts when the tides are moving at 3.5 meters per second.

What’s more, the Axial Skelter is made from recycled plastics and is completely modular. The parts can be 3D printed and shipped as a kit that can be assembled on site. Broken parts can even be melted down and reused to print replacement parts.

Other power companies often use tidal turbines, which have a propeller mechanism to extract energy from water flows. Scotland’s Orbital Marine Power was able to achieve a 2-megawatt output with this design at its installation in Orkney off the country’s north coast.

Another group is testing its propeller-like design in the strong currents off the Philippines, a move that could help wean the region off diesel fuel.

Although the Archimedes screw hydro turbine is relatively new to the sector, the concept has been around for about 10 years. According to RenewablesFirst, power generation from the largest screw hydro generators can reach 500 kilowatts, which is consistent with Spiralis’ claims.

Although working in the tidal energy industry has been challenging, the Spiralis team is confident in their technical and industry knowledge. They continue to raise funds with the goal of building a full tidal energy facility by 2025.

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