The barrage features high-efficiency breastshot-wheel turbines, with hydraulic power transmission. To prove the technology, a single 50m long segment of the barrage could be built as a free-stream tidal turbine. It would deliver a maximum power of 2MW at the Porlock site, and have comparable economics to a floating wind turbine.
Details of the scheme were given by Rod Rainey at a lecture at Southampton University on 17 May 2017, a video of which can be seen here. The slides from the lecture are shown below.