Deep - water offshore sites are an untapped opportunity to bring large - scale offshore wind energy to coastal population centers. The primary challenge has been the projected high costs for floating offshore wind systems. T his work presents a comprehensive investigat ion of a new opportunity for deep - water offshore wind using large - scale vertical axis wind turbines. Owing to inherent features of this technology , t here is a potential transformational opportunity to address the major cost drivers for floating w ind using vertical axis wind turbines . T he focus of this report is to evaluate the technical potential for this new technology. The approach to evaluating this potential wa s to perform system design studies focused on improving the understanding of technical performance parameters while l ooking for cost reduction opportunities. VAWT design codes we re developed in order to perform these design studies. To gain a better understanding of the desi gn space for floating VAWT systems , a comprehensive design study of multiple rotor configuration options was carried out . Floating platforms and moorings were then sized and evaluated for each of the candidate rotor configurations . Preliminary LCOE estimates and LCOE ranges were produced based on the design stu dy results for each of the major turbine and system components . The major outcomes of this study are a comprehensive technology assessment of VAWT performance and preliminary LCOE estimates that demonstrate that floating VAWTs may have favorable performanc e and costs in comparison to conventional HAWTs in the deep - water offshore environment where floating systems are required , indicating that this new technology warrants further study .