SKF and Proteus Marine Renewables gear up for tidal energy revolution

Two decades of experience Proteus is developing three-bladed devices with diameters ranging from up to 26 meters, with the precise specifications depending on the water depth and flow rates at the installation site. "Water is more than 800 times denser than air, so tidal turbines don't need to be anywhere near as big as wind turbines,” says Blaxland. And because the turbines sit on the seabed, entirely underwater, our tidal stream turbines don't disrupt the landscape like wind or solar farms.”   The company has found innovative solutions to many key problems in tidal stream power, including developing a foundation technology that allows machines to be installed or removed in a matter of minutes. Proteus is, says Blaxland, the first company in the world to lift a tidal stream turbine from one site and redeploy it in another.  "Our focus is making devices that are cost-effective," says Blaxland. "In practical terms, that means keeping things as simple as possible while continually improving the design to eliminate risks."

Tidal potential  Under the influence of the Moon's gravity, tides ebb and flow across the world's oceans every day. In the open sea, the effect is small, causing the water surface to rise and fall by about a meter. However, tidal flows are amplified by coastal geography. Estuary entrances, narrow straits, and inlets and can see tidal ranges of over 10 meters, with peak flows of 6 knots (11 kph) or more.  These tidal streams could become a valuable source of renewable energy. “A major advantage of tidal stream energy is its predictability,” says Blaxland. "At a given site, we can tell a customer exactly how much energy they can expect to generate and when," he explains. "That's something you can't do with wind or solar power."  Combining tidal stream power generation with short-term energy storage could provide a significant source of reliable "baseload" electricity. "Validated estimates suggest that there is about 100 gigawatts of exploitable, near-shore tidal power around the world, with 15 gigawatts in Europe," says Blaxland.  In the longer term, Proteus technology could move further offshore to exploit the currents that flow deep in the world's ocean waters. "Deep water currents could provide a compelling renewable energy alternative for some island sites," says Blaxland. "And deep water offers a total potential about ten times larger than shallow water sites. Together, they could provide a terawatt of predictable, reliable renewable energy." That’s about the same capacity as the global wind energy sector today.