UMaine Advanced Structures and Composites Center granted 37th and 38th patents, continues world leadership in floating offshore wind research and technologies

On February 12, 2019, the University of Maine was issued two patents for technologies that prepare Maine to be a world leader in floating offshore wind energy. The two patents are:

  1. US 10,202,170 B2, February 12, 2019. Hull for a Floating Wind Turbine Platform. Habib Dagher, Anthony Viselli, and Mark Dwyer.
  2. US 10,202,174 B2, February 12, 2019. Buoy with Integrated Motion Compensation. Habib J. Dagher, Neal Pettigrew, Anthony Viselli, Rachael Joyce, John Wallinga, Patrick Fikes, and Neil Fisher.

The patent titled ‘Hull for a Floating Wind Turbine Platform’ is the VolturnUS floating concrete hull technology that can support wind turbines in water depths of 45 meters or more, and has the potential to significantly reduce the cost of offshore wind. The innovative VolturnUS design utilizes a concrete semi-submersible floating hull designed to drastically reduce both capital and operation and maintenance costs, and to allow local manufacturing throughout the US and the World.

In 2013, the 1:8 scale VolturnUS was deployed off Castine, Maine for 18 months, making it the first grid-connected offshore wind turbine in the Americas. The VolturnUS successfully completed its 18 month deployment. The data collected during the deployment validated design assumptions and performance, and have been used to further optimize UMaine’s VolturnUS system. The ultimate goal of this technology is to reduce the cost of offshore wind to compete favorably with other forms of electricity generation.

The VolturnUS being prepared for movement
The VolturnUS was launched from Cianbro’s Brewer, ME facility and towed down river to Castine, Maine

Given the extensive experience Maine companies have building concrete structures, the technology is ideally suited for manufacturing in the state. The convergence of UMaine’s established expertise in floating offshore wind, lowering costs, and state commitments to reduce carbon emissions makes Maine poised to lead in the burgeoning U.S. offshore wind industry.

Floating offshore wind turbines are essential in order to tap into Maine’s considerable offshore wind resource. The wind in the Gulf of Maine has the potential to generate up to 156 GW of electricity, which is enough energy to power the state 65 times over. This superior wind resource is located over deep water, which does not allow for traditional, fixed bottom platforms common in Europe to be deployed due to the depth. The patented floating concrete hull technology can support wind turbines in water depths of 150 feet or more and are ideal for use in the deep waters of the Gulf of Maine.

The UMaine patented VolturnUS floating concrete hull technology can support wind turbines in water depths of 45 meters or more

The following is the abstract for the Hull for a Floating Wind Turbine Platform patent:

A hull for a semi-submersible wind turbine platform capable of floating on a body of water and supporting a wind turbine includes a keystone and at least three bottom beams extending radially outward of the keystone. Each bottom beam has a primary beam portion and a column base portion, wherein the column base portion is configured to support an outer column of the hull thereon, and wherein the primary beam portion defines a first ballast compartment therein. The first ballast compartment is in fluid communication with water in the body of water in which the hull is floating.


The patent titled ‘Buoy with Integrated Motion Compensation’ is the Deep CLiDAR technology developed at UMaine that promises to accelerate the development of the US offshore wind industry by providing high quality, low-cost offshore wind resource data, metocean monitoring, and ecological characterization capabilities in remote marine environments.  The Deep CLiDAR is 1/10th the cost of traditional meteorological towers for wind resource assessments, can be deployed in virtually any water depth, able to provide bankable wind speed data up to 200 meters above sea-level, has a fully-integrated metocean sensor package that provides wave and current data, and offers an optional ecological monitoring sensor package for permitting efforts developed with the Biodiversity Research Institute, located in Portland, Maine.

The patented UMaine DeepCLiDAR technology deployed off the coast of Maine

The following is the abstract for the Buoy with Integrated Motion Compensation patent:

A floating buoy includes a buoy hull having a tower that extends outwardly from the hull. A plurality of sensors are mounted either on the buoy hull, within the buoy hull, and/or on the tower. The plurality of sensors includes at least one met-ocean sensor, at least one ecological sensor, and at least one wind speed measurement sensor. The floating buoy further includes an autonomous power system that is configured to provide electrical power to each of the plurality of sensors. The wind speed measurement sensor may be a Light Detection and Ranging (LiDAR) wind speed measurement sensor, a surface level wind speed sensor, an ultrasonic wind speed sensor, or SODAR.

To see the full list of the Center’s patents, click here.