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www.sname.org/sname/mt July 2013 Validating the Wave Energy Model e environmental conditions are di erent for every poten- tial deployment site, including local changes in wind, wave, and current conditions, as well as sea oor geophysical and geo- technical conditions where anchors interface. e result is a cascading impact on design requirements, which creates chal- lenges in de ning common requirements for infrastructure while keeping overall costs competitive. Energy conversion and PTO We performed extensive cooperative research with the Wallace Energy Systems & Renewables Facility at Oregon State University (OSU) on direct-drive systems to increase e ciency and reduce operation and maintenance (O&M) costs before selecting the DDR PTO. Reliability and survivability are among the most important design criteria for the design of an unmanned o shore system. A DDR PMG enables the elimination of mechanical systems and components and the electrical control of PTO load, reducing risk of failure and making the PTO system more robust. ere also is increased material e ciency relative to the LDD gener- ator alternative. Power from ocean waves is pulsed, with high force and low speed, and it is most e cient to smooth the power pulses early in the energy conversion process. Power smooth- ing can cause energy loss, and for most e cient conversion, it is desired to be able to convert a wide range of speeds and torques, minimizing cut-o regions. e use of a direct-drive generator, coupled with power electronics, enables an e cient and wide range of operation. e lifecycle cost of a WEC includes both capital and O&M components. A WEC is designed to operate 24/7 for 20 years with roughly 10,000 wave cycles a day under heavy loads. The O&M costs can dominate when considering The technical evolution of the Columbia Power WEC systems.