Offshore wind to set sail, studies find

Source: Eric Marx, E&E Europe correspondent • Posted: Thursday, January 7, 2016

The dawn of a more robust era in offshore wind may be breaking, according to two recent reports on floating wind power that show long-inaccessible deepwater sites with some of the highest winds on Earth now appear to be within reach.

One report, a polling result commissioned by the European Wind Energy Association (EWEA) at its annual conference in November, finds the sector to be already “winning the cost argument” based on simpler installation requirements. It projects electricity generation as low as $93 per megawatt-hour and focuses on construction of floating foundations as the main design challenge. That would be competitive with traditional offshore projects if floating wind reaches commercial-scale deployment in the 2020s.

The second, issued by U.K. nonprofit the Carbon Trust, spotlights Scotland, France and Japan as the three most commercially attractive markets in the near term. It projects a similar cost forecast over the next decade but offers a more comprehensive analysis of 33 floating wind turbine concepts that have thus far taken to the waters.

“We have seen that these early demonstrations have been successful from a technical perspective,” said Rhodri James, a Carbon Trust analyst and lead author of the report.

A great deal now depends on the launch of array-sized wind farms, starting with Statoil’s 30-megawatt Hywind pilot project in Scotland and Principle Power’s 25 MW WindFloat Atlantic project in Portugal.

“The important thing,” James said, “is to show costs can come down considerably as deployment is scaled up.”

Front-runner technology and access markets

At its most basic, floating wind is a turbine whose foundation is largely decoupled from the seabed, with only the anchors having to cater to different geologies. The technology could prove a bonanza for countries like Scotland that find themselves restricted to shallow sites far out to sea. Others, like Portugal and Japan, have little choice. Confronted by steeply plunging seabeds, those nations are now fully committed to investing in the fledgling technology.

The studies indicate that three dominant classifications of floating wind structures have emerged. According to the EWEA survey, “semi-submersibles” are now engendering the most industry support — outperforming others known as “spar-buoys” and “tension-leg platforms.”

Semi-submersibles are favored because of a low draft, which is said to allow a more flexible application and simpler installation. In use since 2011 with the WindFloat project, triangular platform design — which floats semi-submerged below the water — is also favored by floating foundation specialist Ideol, which has plans to develop a 500 MW wind farm in France as well as additional projects in Japan.

The first full-scale floating turbine went to sea in 2010 in 200-meter-deep waters off the coast of Norway. It’s been sending electricity to the grid over the past five years, but with a radically different spar-buoy design that sees a single, very long ballast column sinking 100 meters below the sea surface. Because the center of gravity is lower in the water, the upper parts are usually lighter, thereby raising the center of buoyancy.

Both designs are loosely anchored to the seabed with mooring lines. Each of the floating structures can be assembled at port and towed to the site by widely available tugs. Reduced installation costs are the No. 1 advantage, with competing solutions looking to balance stability and long-range performance of the floaters and its cost.

Analysts say the aim of expanding the wind farm to 100 MW in time for the 2020 Tokyo Olympics is achievable, so long as demonstration projects show ample cost reductions.

Global ambitions

Unlike fixed-bottom wind farms where turbine assembly is undertaken offshore, most floating wind concepts are designed so that the entire structure can be assembled at port, removing the need for expensive heavy-lift vessels. This is likely to be particularly significant in emerging offshore wind markets, such as the United States and Japan. In those countries, the availability of heavy-lift vessels has been a considerable bottleneck to constructing fixed-bottom offshore wind farms.

The Coos Bay floating wind power project off the coast of Oregon has $47 million in Department of Energy funding support and will likely be the first project on the West Coast.

As for established markets like Scotland, the advantage lies in leveraging existing infrastructure and supply chain capabilities from leading offshore turbine manufacturers, as well as the offshore oil and gas industry.

“The critical thing here is the ability to access high wind speeds — which drive revenue — and the savings that can be achieved in electrical transmission,” James said.

“As wind farms move further from shore, transmission losses increase, and from 100 kilometers from shore it becomes necessary to use more expensive high-voltage direct-current [HVDC] technology. Thus, by accessing sites nearer to shore, floating wind can avoid such challenges and gain a competitive advantage,” he said.

This makes floating wind a more global market from the outset, by necessity but also as an outgrowth of crossover synergies.

“Floating wind is not a new industry but an evolution of an existing one that utilizes many out-of-the-shelf components from the offshore wind market,” James said.

Siemens and Vestas, for example, supplied specially designed turbines for the Hywind and WindFloat projects, respectively. Yet most floating foundations claim to be turbine-agnostic, although minor design modifications are expected.

“It should be stressed that we don’t see floating technology to be in direct competition with fixed-bottom technology,” James continued, “but rather as an additional alternative for developers to unlock new sites to enable a lower cost for offshore wind energy in general.” The chosen technology — whether floating or fixed — will simply be decided based on the option that provides a lower levelized cost of energy.

Future collaboration

That Japan is rapidly taking the lead in floating wind technology is, in part, due to huge investments made by the government. The industry remains reliant on subsidies, so the outlook for the sector depends on government policy and is subject to uncertainty.

Clear articulation of the benefits to government is one of the challenges. The Carbon Trust report was commissioned for this reason, but the effort may be falling on deaf ears. Three projects in Scotland, for example, find themselves in a high-risk moment. Each has the opportunity to leverage existing port infrastructure and supply chain capabilities, but because of a pending 2018 cut-off on subsidies, all three are operating under a cloud of uncertainty.

Developers are forming consortiums in order to share risk and allow specialization, thus increasing efficiency. Yet further industry collaboration needs to occur, James said, citing, for example, the Carbon Trust’s own Offshore Wind Accelerator program — a collaboration among nine of Europe’s leading offshore wind developers, with support from the U.K. and Scottish governments.

The program has delivered a number of successes by supporting the commercialization of several novel cost-cutting technologies, including innovative foundations, cables, access vessels, wind resource assessment devices and wind farm modeling tools, all of which have contributed to reducing the cost of energy for offshore wind.

“We believe that a similar approach in floating wind could help to accelerate its commercialization,” James said.