Floaters. Tethered offshore wind turbines

Floaters. Offshore wind turbines.

Floaters are offshore wind turbines that are anchored by mooring lines. They can be installed in much deeper water than current offshore wind turbines, which have fixed foundations located less than 160 feet of water. If water is deeper than that, the cost of fixed turbines becomes prohibitive. Also, the cost of installing floaters may become cheaper than for fixed. Plus, there are far more locations near urban centers for floaters. So, looks like floaters is the way to go.

Floaters can be manufactured in ports or on major rivers, then towed to sea completely assembled, then tethered to the ocean floor. This is not new technology, floating offshore oil rigs have been in operation for years, sometimes in very deep water.

Maine is a leader in floaters

Maine is a leader in this. The heating oil spike in 2009 triggered creation of a pilot floater. It worked fine, however the project went dormant until now.

Backed by Maine’s Legislature with one vote short of a unanimous approval and financial help from the U.S. Department of Energy, the team erected a model wind turbine, one-eighth the size of a conventional turbine, and put it on a float. Then the team had a tugboat tow it out to an offshore site.

It was small but strong enough to stand up to powerful winds and crashing waves, and made history in 2013 as the first floatable wind turbine to feed electricity into the U.S. power grid.

On paper that looked impressive because Maine’s offshore wind-making potential is 36 times greater than the state’s total electricity demand. In the following years, not much happened, but recently two serious industry players joined Maine in a $100 million partnership to build a full-size floating turbine near the site

Floaters in California

Castle Wind is hoping to build a 1 GW floating wind farm in Morro Bay in California.

Castle Wind Offshore (CWO) will consist of approximately 100 floating offshore wind systems (FOWS) that will harvest the vast offshore wind resources for the benefit of the California electric consumers. Each FOWS will consist of a commercially available floating support structure and a large offshore wind turbine generator (OWTG) with a nameplate capacity greater than 8MW. Each FOWS is moored to the ocean floor using conventional properly sized, vertical load, drag imbedded, or torpedo anchors, a technology that requires no piling and is well suited for deep and variable seabed conditions. The installation is completely reversible, i.e., no permanent infrastructure is left on the sea bed upon decommissioning and performed with minimal acoustic disturbances. Individual FOWS are electrically interconnected with inter-array cables to form an offshore wind farm.