In May the University of Maine-led, DeepCwind Consortium launched the VolturnUS prototype offshore wind turbine.The floating platform represents a series of “firsts” for a fledgling industry. Is this the game changer that will open up the US coast to windpower development? A University of Maine (UOM) team launched the first American floating wind turbine, VolturnUS, on May 31st off the coast of Maine that could open up possibilities for wind farm development on the U.S. Atlantic and Pacific coasts as well as Hawaii. The VolturnUS prototype is a 65-foot-tall turbine, a one-eighth-scale version of a 6-megawatt full-scale turbine which UOM hopes to deploy off Maine’s coastline in 2016.  The VolturnUS could prove to be a game changer for the US in the development of offshore windpower. Although the US has the largest wind generated power in the world, all of the wind power is generated onshore. Currently there are ten offshore wind farm projects in various stages of development, but they largely follow the European model. The floating wind turbine platform significantly differs from those offshore wind platforms currently operating overseas as it is designed to operate in open water similar to offshore oil platforms.  With the support of a $12 million DOE (Department of Energy) investment over five years, University of Maine and its DeepCwind Consortium project partners conducted extensive design, engineering and testing of floating offshore wind turbines, followed by the construction and deployment of its revolutionary VolturnUS prototype.  “There are many firsts here today,” said Habib Dagher, Director of the University of Maine’s Advanced Structures and Composites Center. “Not only is VolturnUS the first floating wind turbine in the US, it’s the first turbine tower to be completely made of composites, and the first concrete / composite floating base in the world.”  The VolturnUS unit was assembled at Cianbro, an engineering construction company that partnered with the UOM to fabricate the floating wind turbine. Innovative Design The UOM tripod design was found to be the most stable compared to designs such as the turbine-mounted-on-a-buoy or spar buoy promoted by the Norwegian oil and gas giant Statoil. The concept will now be tested in Atlantic Ocean conditions. Stability is critical to reducing wear and tear on the turbine driven propeller blades and keeping maintenance costs low. “It’s like a tri-marine boat. It floats on three outer arms and the frame carries the load of the turbine. Our engineers made sure it could “breathe” in a balanced way so as waves hit the structure, it has the flexibility to take on some of that impact,” said the chief engineer in charge of offshore structural design, Antony Viselli.  Concrete replaces traditional steel foundation. The semi-submersible base is made of concrete strengthened with composite materials, which eliminates the need for steel construction. Dagher said, “In Europe offshore wind turbines have a life of about twenty to thirty years. The VolturnUS has a hundred year life expectancy. That’s why we developed the concrete base.” The concrete base reduces welding, man hours and uses a forming process that provides innate strengths lacking in a welded steel configuration. This approach has been used in composite materials for aircraft but is now being tested in a marine setting. This could be a huge labor saving opportunity compared to steel-based platforms. A European designer noted that man-hours for wind turbines in Europe are skyrocketing because of insurance and marine certification requirements for super quality controls to insure structural integrity. The UOM Advanced Structures and Composite Center is providing a new paradigm for offshore construction that could help the US regain the lead in offshore wind development. The composite tower also eliminates steel fabrication and welding. It creates the potential for a more stable and cost-effective structure. Floating turbines may replace fixed foundation structures. Initially, construction in Europe had focused on shallow water for the base of fixed foundation wind turbines, which required in water construction of foundations followed by installations of wind turbines using jack up vessels costing $100-million or more. This is the design proposed for several U.S. Atlantic coast projects. The UOM project may strengthen the case for building floating turbines and anchoring them to the seabed in deep water such as off the Maine coast. Deepwater semi-submersible structures are increasingly used in the oil and gas industry. Research shows that wind generation is optimized when moving further out to sea and deep water opens up wind farm opportunities on the U.S. Pacific coast and in Hawaii. UOM believes that the maintenance costs of the floating platform should be less than fixed offshore wind structure. Dagher says the VolturnUS floats has mooring lines with self-embedding anchors, like ships. It can be towed out to sea, drop its anchor and be plugged into the grid. Repairs require towing the turbine back to port for work rather than performing expensive maintenance work at sea. Time will tell whether storm and wind will validate this claim. Wind turbine manufacturers have expressed concerns that the wear and tear associated with floating platforms will be higher than fixed platforms in shallow water or such as on land. The testing of the VolutrnUS should provide important information on this issue. Dagher told participants at a Maine Industry Initiative Webinar on June 5th that there had been extensive research on the environmental impact of the wind turbines and that floating turbines can be towed far enough out to sea so as not to be visible from land.  Cost Issues   Paul Williamson, director of the Maine Wind Industry Initiative based in Portland, Maine says the current cost of power generated by one of the offshore floating wind demonstration projects will be expensive and cost around 27-cents per kilowatt hour compared to current 7-cents per kilowatt hour for conventional power. However, as projects move towards commercialization, developers expect to produce power at 10-cents per KWH. Offshore Gridlock Grid integration is the big unanswered question for developing offshore wind power. The mass wind farm development off the North German coast has run into problems integrating offshore wind into the power grid, because of the need for transmission operators to build and pay for new transmission lines that connect offshore wind farms to German population centers that are distant from ports such as Bremerhaven where off-shore wind turbine construction is proceeding. In addition, offshore transformers are needed to transform DC current from distant wind turbines at sea to land based power grids using AC current.  A European designer who has worked on one such project says the floating transformers are proving very expensive to design and build as steel platforms. Siemens HVDC Platform  The German electronics giant, Siemens, expects to complete an offshore High Voltage Direct Current (HVDC) platform to connect to a North Sea wind farm by 2015. The Atlantic Wind Connection is proposing to build an offshore transmission line using HVDC platforms to connect wind farms to the grid off the New Jersey coast. A Game Changer? The goal of the VolturnUS prototype is to establish the operating technology for an offshore pilot wind farm. The UMaine Composites Center and its partners have invested $96-million in developing a 12-MW pilot farm and plan on connecting the first full-scale unit to the grid in 2016. This pilot wind farm could be a game changer, the type of project that could launch a gold rush of offshore activity rivaling the pursuit of offshore oil in the Gulf of Mexico. “The Castine offshore wind project represents a critical investment to ensure America leads in this fast-growing global industry, helping to bring tremendous untapped energy resources to market and create new jobs across the country,” said Jose Zayas, director of the Energy Department’s Wind and Water Power Technologies Office. According to the DOE, offshore wind represents a large, untapped energy resource for the US, offering over 4,000 gigawatts of energy potential- four times the nation’s current total generating capacity. According to a recent DOE sponsored report, a U.S. offshore wind industry could support up to 200,000 manufacturing, construction, operation and supply chain jobs across the country and drive billions in annual investments by 2030.