The assignment discusses the concept of diffuser augmented tidal turbines as a means to increase energy efficiency in low-velocity tidal streams. The use of these turbines can extract more energy than conventional turbines, resulting in increased output power and reduced sound pollution. Additionally, the diffusers can be manufactured using low-cost materials, making them a cost-effective option. However, there are limitations to their use, including complex manufacturing and installation requirements, vibration issues due to higher RPM, and additional support structure needed due to increased drag.