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www.sname.org/sname/mt October 2012 hub heights. Similar to shallow-water installation, transitional depth installations also require expensive, specialized installation vessels and equipment.At deeper water sites, over 60 m, it might be more economical to use floating substructures, but the technology is at a nascent stage of development. The development of ?oating wind technology will dictate a new set of wind turbine design specifications to handle the coupled hydrodynamic/aerodynamic forcing, as well as the added stability requirements. These new requirements will initially add a higher degree of technical risk but with a potentially higher payoff in the long term. The major incentives for developing ?oating systems include: s P O T E N T I A L F O R R E D U C I N G C O S T S T H R O U G H system design site independence and greater opportunities for mass production s G R E A T E R P O T E N T I A L F O R F U L L S Y S T E M A S S E M B L Y at quayside and reduced load-out cost s H I G H E R W I N D S P E E D S A N D E N E R G Y C A P T U R E over deeper waters s M O R E T H A N O F T H E 5 3 R E S O U R C E P O T E N T I A L being greater than 60 m in depth, and s R E D U C E D I M P A C T S O N H U M A N A C T I V I T I E S and environmental ecosystems. A vast number of permutations of ?oating offshore wind turbine platform con?gurations are possible, but in general they can be divided into three general types: spars that obtain their stability from ballast; semi-submersibles that achieve stability through buoyancy; and tension- leg platforms (TLP) that rely on mooring line tension for stability. The graphic on page 34 shows examples of floating offshore platform architectures that currently are being considered. The optimum platform must deliver dynamic behavior that minimizes loads on the turbine and structure while also being simple to build, deploy, and maintain at sea. Specialized turbine control systems that account for both wind and wave forces, and which limit motions, also may be used. To date, two MW-scale ?oating wind turbine prototypes have been successfully deployed. In 2009, Statoil installed the ?rst full-scale ?oating wind turbine, which uses a ballasted spar type substructure and was ?tted with a 2.3-MW Siemens turbine. In 2011, U.S. company Principle Power deployed its WindFloat concept, a semi-submersible design with a 2 MW Vestas turbine (see Demonstrating Floating Wind Power? beginning on page 48 in this issue).Department of Energy activities For offshore wind energy to be successful in the U.S., costs must be reduced so that it is competitive with other electrical generation sources. In addition, timelines and uncertainties associated with project development have to be reduced. The DOE, as a non-regulatory agency, is in a unique position to provide national leadership through collaborative partnerships with other federal agencies, the states, academia, and industry. DOE supports innovation through funding opportunities, small business innovation research grants, international and domestic research and development partnerships, and the National Laboratories. After receiving input from all stakeholders and studying the offshore wind industry overseas, in September 2010 DOE published the report, Large-Scale Offshore Wind Power in the United States: Assessment of Opportunities and Barriers . In February 2011, DOE released A National Offshore Wind Strategy: Creating an Offshore Wind Industry in the United States in conjunction with the Department of the Interior. The strategy sets a goal to deploy 10 GW of offshore wind in the U.S. by 2020 and 54 GW by 2030. To achieve these goals, the strategy calls for reducing the cost of offshore wind energy and promoting responsible deployment through activities in three focus areas: s 2 E M O V I N G M A R K E T B A R R I E R S T O F A C I L I T A T E deployment and reduce technical challenges facing the entire industry s D E V E L O P I N G I N N O V A T I V E T E C H N O L O G I E S T H A T lower the cost of energy of offshore wind plant systems, and s D E M O N S T R A T I N G A D V A N C E D T E C H N O L O G I E S that verify innovative designs and technology developments and validate full performance and cost under real operating and market conditions. DOEs funding for offshore wind activities is aligned with the national strategy. To date, DOE has announced more than $230 million of funding opportunities supporting development of the offshore wind industry. (All DOE funding in future years is subject to congressional appropriations.) Removing market barriers In 2011, some 22 awards were made, totaling $16.5 million, to reduce market barriers that are inhibiting development of the offshore wind industry. These projects address such factors as the comprehensive environmental data needed to support the siting and permitting process; the complexities and unknowns of providing grid integration and transmission access for offshore Similar to shallow- water installation, transitional depth installations also require expensive, specialized installation vessels and equipment.