Environmentally friendly blade runner One manufacturer of large wind energy blades has a maritime solution to the problem of transporting very large blades. A motor barge specifically designed to move its largest blades has entered service off the UK's south coast. Bladerunner 2 has a large, unobstructed main deck that will be
able to carry blades up to 65m long being developed to drive offshore wind generators of up to five or six megawatts power. Smaller present-generation blades can be stacked on deck two tiers high. Currently loads comprise 26 to 40m blades produced by UK offshoot of Danish specialist
Bladerunner II will be able to carry blades up to 65metres long
NEG Micon Rotors Ltd at its riverside factory in Newport, Isle of Wight. Blades, embarked onto the vessel at Newport by straddle carrier, are taken to Southampton Docks where they are offloaded by crane ready for transhipment elsewhere. BR2 is a novel, flat-bottomed vessel that draws only 0.65m of water when loaded, despite being 75m long and having a gross registered tonnage of 416 tonnes. The ship can therefore operate in the shallow River Medina over a substantial tidal window. It is 'doubleended' and travels in both directions, a high 'Solent-bow' going first when under way at sea, and a low 'Medina bow' first entering the matching purpose-built dock at Newport, where blades can be embarked over it without difficulty. The wheelhouse, elevated to afford line of sight over the cargo, is operationally reversible, the master reversing his seat and control sense as required. To operate in the environmentally sensitive River Medina, BR2
has to meet strict criteria. The ship is propelled by three Schottel pump-jet units rather than conventional propellers so that there is minimum disturbance to the river bed. These 360-degree rotatable units also give it the manoeuvrability needed to enter the close-fitting dock at Newport. When the craft is correctly docked, the propulsors are directly over anti-scouring pads installed on the mud bed. Under way, the ship is notably smooth and quiet, and creates minimal wash. Bladerunner 2 joins its smaller but similarly designed sister ship Bladerunner 1. NEG Micon, which owns and operates the vessels, says both are needed to cope with the expected growing scale of operations at Newport. BR2 was built in steel by Aveco (Teesside) Ltd. John Pattisson Associates of Poole designed both vessels and the Marine Transfer Facility at Newport, as an integrated environmentally-impeccable blade transport system.
Downwind 'streamer' wind turbines Wind turbine blades that could 'give' in strong winds by streaming away from the wind on hydraulic hinges could be made much lighter and less expensive than conventional blades, according to The Wind Turbine Company in Washington, USA. Normal blades have to be made stiff enough to resist being bent back in high winds so far that they strike the support tower behind them. This requires a combination of careful design and copious use of materials. The Wind Turbine Company argues that if the rotor were to be mounted behind the tower rather than in front of it, lighter more bendy blades could be produced that would shed load in high winds by streaming away from root hinges. Such blades would be both lighter and more
economical to produce than conventional blades. Operating loads on the hub and turbine would be reduced. Downwind designs are, however, subject to interference effects caused by the tower and must be optimised to local wind conditions. WTC president, Larry Miles, argues that advances in computer technology now make it feasible to make the necessary engineering analyses so that such rotors can be viably produced and operated. He estimates savings of up to 50% in materials compared with conventional three-blade rotors of equivalent capacity. Furthermore, he says downwind rotors unlike most upwind types - are self-orienting and do not need costly drive systems to align themselves into wind.
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