Traditional designs use a rotating blade to extract energy from the moving water. The diameter of this blade is limited by the water-depth and this reduces the amount of power that can be generated in shallow water.
Pulse Tidal’s technology overcomes this limitation by using a wide, flat machine where the blade length is not limited by water depth.
At a typical site where depth is limiting a Pulse generator will extract more than 4 times as much energy as a single traditional turbine.
Being able to site in shallow water means the power generation can be much closer to shore and in calmer waters. The company says this technology can deliver low-cost, utterly reliable renewable energy, and may be able to do it for less cost than offshore wind.
Ocean Power Magazine has more. They are a great resource for everything on ocean power R&D and deployment.