Winding up for wind power
  from: Offshore Engineer
  by: Russell McCulley
  Thursday, July 03, 2008

With energy costs rising and government officials calling for more emphasis on renewable sources of power, Texas is making a bid to become the leader in US offshore wind. But significant hurdles – technological, financial and environmental – remain. OE Gulf of Mexico editor Russell McCulley looks at some of the issues state leaders and energy companies are grappling with in the effort to bring wind power to the Gulf of Mexico.

The state of Texas, already the US leader in wind energy generation, is positioning itself to become the first in the nation to deploy high-capacity wind turbines in the Gulf of Mexico.

But the industry will have to overcome a number of hurdles to meet the ambitious goals state leaders have proposed to diversify Texas’ energy portfolio, and even more ambitious goals set forth by the federal government that call for 20% of the nation’s energy to come from wind by the year 2030.

The timing seems right for the emerging industry: spiraling hydrocarbon prices and growing interest in renewable energy sources have spurred companies to pour research and development dollars into alternative power, with wind considered among the cleanest and most cost-effective. Texas has a track record to point to: the state has 5300MW of installed wind generation, principally in sparsely populated West Texas, and plans are in the works to add more than 40,000MW.

The Gulf of Mexico looms large in those plans. Texas’ General Land Office (GLO), which manages mineral rights for more than 20 million acres of land, including ‘submerged’ state land extending 10 miles offshore on the Outer Continental Shelf, has awarded five offshore leases to Louisiana-based Wind Energy Systems Technology (WEST), which plans to install large-scale wind farms on the sites. GLO deputy commissioner Dwain Rogers says the company is still gathering data on the tracts but has filed documents with the US Army Corps of Engineers seeking permission to proceed with its plans.

The wind leases represent the first competitively bid leases for offshore US, Rogers says, with each projected to produce 250MW or more by 2011 or 2012. ‘The state of Texas is committed to the wind industry,’ he says. ‘We support it and want it to flourish here in Texas.’

In June, the city of Houston hosted for the first time the American Wind Energy Association’s annual Wind Power conference, which drew far more than the 12,000 attendees registered for the event. At the meeting’s outset, Danish wind power giant Vestas Wind Systems announced that the company had selected Houston as the site for its North American research center, which is scheduled to open in 2009 and employ at least 100 when it becomes fully operational in 2010. Company officials said research will focus on mechanics, electricity, control systems, advanced materials and aerodynamics, with the goals of increasing turbine efficiency and lowering the cost of wind power production.

The far West Texas wind farms have proved successful, but their remoteness means power must travel great distances to reach substantial markets. Another disadvantage is meteorological: the wind in West Texas blows strongest at night, when demand for power is lowest, and diminishes during peak daylight hours, when demand is high.Winds along the state’s coastal waters, on the other hand, typically remain strong during the day. As in the rest of the nation, population tends to be concentrated near the coastline.

The cost of turbine installation and maintenance increases dramatically when the activity moves offshore. ‘I don’t think there’s any doubt that costs escalate offshore,’ says Lane Sloan, director of the Strategic Energy Alliance at the University of Houston. ‘And you have to have transmission lines – that becomes more of an issue.’ But the greatest challenge, Sloan says, could prove to be the weather. Strong Gulf hurricanes produce not only sustained winds and violent gusts, but multidirectional wind patterns; building structures that can withstand such extreme wind and tidal surge presents significant engineering challenges, he says. ‘The big issue with the Gulf of Mexico is going to be hurricanes, and how one addresses major storm patterns like that.’

Dealing with hurricanes is a subject that oil and gas exploration and service companies have come to know well, Sloan says, and the industry ‘represents a significant knowledge base’ that can be tapped by offshore wind power developers. ‘That’s one of the reasons Vestas found us attractive,’ he says.

Another draw for the offshore wind industry could be Texas’ traditionally laissez-faire attitude toward energy development. Although there are stronger, more consistent winds off the nation’s northeastern Atlantic coast, intense opposition among coastal residents and environmentalists have stymied proposed projects in Massachusetts and Delaware. ‘In Texas, I think you have a much more receptive audience,’ says Bob Thresher, director of the National Wind Technology Center near Boulder, Colorado, which conducts research and development in wind turbine design. Not that Texans have been unanimous in their support: some onshore wind farm proposals near the coast have run into opposition from environmentalists, who say the turbines would pose a threat to the migratory birds that feed in the state’s coastal regions. Developers’ proposals to install radar to track large migrating flocks and shut down turbines during especially active periods have done little to quell those fears.

Offshore wind farms would pose less of a threat to wildlife, says Rogers, citing studies that show the offshore turbines would be situated much lower than the altitudes at which migrating birds approach the coast. In bad weather, when the birds stick closer to sea level, radar could alert turbine operators. ‘We really have not heard that many voices raised in opposition to our offshore leases,’ he says.

The bigger obstacles, perhaps, lie in technology and logistics. Offshore projects in the UK – which has set a goal of generating 15% of its energy, roughly 35GW, from renewable sources by 2020 – have been beset by problems, including mechanical failures, false fire alarms and difficulty gaining access to the installations in rough weather.

Most of Europe’s turbines are smaller than what would be required in the Gulf of Mexico – 3MW or less – although two 5MW units have been installed in the North Sea, 25km off Scotland’s eastern coast, in 45m of water. The Beatrice Wind Farm project is viewed as a prototype for the type of wind farms that could help Europe meet its renewable energy goals, but the large-scale offshore wind industry is still considered to be in its infancy. ‘They’ve had a lot of operational problems’ with the 5MW units, says Thresher. ‘But it’s a tough environment.’

The Beatrice project makes use of the area’s hydrocarbon production infrastructure, piggybacking on existing subsea oilfield cables to transmit power back to shore. The practice could be used in the Gulf as well, with its extensive shallow water platform and pipeline infrastructure. But Gulf projects will still have to contend with a less-than-stellar record of mechanical performance among turbines: the life spans of drive trains and gearboxes tend to be short, Thresher says. ‘The big challenge is getting the turbines to work properly, and to have access.We’re still learning how to do that offshore.’

Bigger turbines than those currently in use in Europe will be needed for the Gulf, he says. According to the US Minerals Management Service, the larger size will help the units take advantage of steadier and higher velocity winds and economies of scale. ‘As wind speeds tend to increase with distance from the shore, turbines built farther offshore will be able to capture more wind energy. However, as the distance from land increases, the costs of building and maintaining the turbines and transmitting the power back to shore also increase sharply. To capture the wind power and reach the economies of scale needed to make the far offshore sites financially viable, it is generally believed that 5MW or larger turbines will be needed,’ the MMS said in a paper on wind power.

‘We probably need blades of 70-80m’ in length, Thresher says, and some manufacturers are envisioning 100m blades. ‘We really don’t know the limit,’ he says. High steel and cable prices have inflated the costs of new turbines, and support and installation vessels – already in short supply, and charging high day rates – will be in even greater demand.

As the offshore industry grows, many expect service companies to expand their fleets to include specialty vessels that can service and deploy turbines. And new technologies have already been introduced. In the Beatrice project, led by SeaEnergy Renewables, a consortium of Scottish energy companies, researchers developed a jacket structure to fasten the turbine and tower to the seafloor. Most of the assembly work – turbine, rotor, blades and tower – was done onshore to minimize costs. SeaEnergy business development director Allan MacAskill predicts the costs of installation and service for offshore wind will decrease as the technology grows and as companies ramp up production of vessels to meet demand.

But outside forces still make offshore wind development in the US an iffy proposition. If the price of power continues to rise, and failure rates decrease, Thresher says, ‘I think offshore wind is going to make sense.’ But considerably lower energy prices could thwart the effort to find alternative sources of electrical power. In Texas, officials are hoping that the momentum continues. As state revenues from oil and gas dwindle, says Rogers, ‘we see renewable energy as a way to replace that revenue stream. And Texas is on its way to becoming a big player in the wind industry.’OE

Click here to register to receive your own copy of Offshore Engineer each month.