Transport companies, in particular, are affected by the size of the components, the distances they must travel and the permitting issues involved. Meanwhile, connection of remote sites to the grid means greater expense for owners, especially when a lack of grid infrastructure is proving to be a major impediment.
In the US the wind blows most consistently across the sparsely populated Great Plains and across the high elevations of the Appalachian Mountains in the east and the Rockies in the west. John Dunlop, senior technical programs manager at the American Wind Energy Association (AWEA), says: "It’s logical to site large wind farms with large turbines away from cities. Cities tend not to be built in windy places, and if you go to more remote areas people are less likely to object."
Delivering large, yet relatively delicate, items like blades to such a site can prove problematic, requiring temporary turning roads to be built and removed afterwards. "By investing in properly designed access roads, companies can minimise project costs, as well as potential financial- and time-loss from road failures," says John Bolton, director of marketing for Tensar, a supplier of ground-reinforcement systems called geogrids.
When strengthening existing roads or building new ones, the geogrid mesh layer stabilises the aggregate layer, reducing the thickness required to carry loads. This allows for heavier loads, reducing the amount of traffic and avoiding associated damage to rural roads by the huge vehicles involved in delivering turbine components. More stable roads help to minimise costly damage to turbine blades.
"Geogrid-designed roadway solutions are safe, minimise imported material cost, are faster to construct, and have reduced environmental impact through lowered carbon emissions during the construction process," Bolton says. "As energy companies begin to react more to the data supporting the selection of the best-fit sites for wind power generation, the chances of this data pointing to a location that is without construction challenges decrease."
The demand for companies like Tensar to help resolve these site-work challenges will grow, cementing their place as key members of the supply chain. In other sectors, Tensar is increasingly working on remote developments, and Bolton believes the same applies for wind sites. "The supply of good sites needing little to no modification prior to construction will dwindle and challenging sites will become the norm," he says.
The biggest constraint, however, says Dunlop, is inadequate transmission. "This, and who pays for the $100 billion upgrade of the US transmission system — which should probably switch from AC to DC too — are the most frequently asked questions."
"Transmission boils down to the three Ps," says Dunlop. "Planning, permitting and paying." Some states see no benefit in upgrading transmission lines so that a developer can export its power to another state. Some private developers are ready to take matters into their own hands and build their own transmission lines.
"Transmission is actually only around 10% of the cost of delivered energy," says Dunlop. "It’s a relatively small cost, which some private wind farm developers are prepared to meet themselves."
Even if the transmission constraints are overcome, a robust supply chain and construction strategy for large turbines will be needed for remote locations. Developer RES Americas is leading the way. Steve Reutcke, vice-president, construction projects, north central and northeast, told this year’s AWEA conference that he had identified seven key elements: a competitive process for request for proposal; low-cost performance; risk aversion; open book procurement; value engineering; schedule compliance; and health and safety.
"We are seeing wind farms built in increasingly complex and challenging locations. This brings issues around geology and interconnection," Reutcke says.
Training and site design
Design and construction play their part at remote sites, he explains. "We instigate comprehensive site investigations using experienced civil and electrical in-house engineers. We use enhanced design evaluation techniques, including turbine site capability studies."
Onsite teams in such locations require additional training. "We have site-specific safety inductions, weekly safety meetings and monthly ‘all-hands’ meetings," Reutcke explains. "RES also has in place a system of ‘near-miss’ identification and tracking. All this is backed up by a ‘three-strike rule’ disciplinary process and monthly audits for site safety accountability."
It would be regrettable if, having overcome the problems of technology, urban objectors and logistics to get large turbines to remote sites, wind energy development was to founder over transmission, says John Dunlop. "The US could produce nine times more electricity from wind than it does now," he says. "The state of Minnesota alone could produce five times more wind power than the world’s current leader, Germany. There’s no excuse not to. It’s an incredible resource."