The document describes MAREN, an INTERREG project that aims to optimize energy extraction from marine renewable resources while minimizing environmental impacts. MAREN involves partners from several European countries studying different renewable energy types. The project will produce high-resolution models of resource potential and environmental impacts for case study locations. It will also compare environmental assessment protocols across regions and create a database of marine renewable projects. The UK case studies include modeling potential tidal barrages, lagoons, and tidal stream and wave projects in Wales and England. The Hydro-Environmental Research Centre is modeling impacts of technologies like the Cardiff-Weston tidal barrage and tidal stream turbines on hydrodynamics, sediments, water quality and the environment. The document proposes a