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3 8 C O M P O S I T E S W O R L D . C O M Applications Applications TOWERLESS TURBINE Airborne system powers rural locales Modular composites update Sao Paulo ferries PUBLIC TRANSIT Te Brazilian state of São Paulo recently undertook a project, through its state-controlled company DERSA, to improve public transporta- tion infrastructure. Formed in 1969, DERSA manages state highways and operates ferry boat services along 622 km/383 miles of coastline. Scheduled for completion this year and intended to reduce commute times by 30 percent, the project involved reftting 12 car ferries and replacing their steel superstructures with composite constructions. DERSA engaged distributor Barracuda Advanced Composites (Rio de Janeiro, Brazil) not only to specify and supply the composite materials, but also to engineer the superstructure design. Barracuda's CEO Jorge Nasseh says the project called for a com- posite deck, side-rail assemblies and a topside operator cabin as prefabricated, 3m by 2.4m (9.75-f by 7.8-f) fanged panels, which could be assembled and bolted onto the existing steel hulls. Te modular design allows the addition of panels to ft the various ferry lengths, which range from 35m to 48m (114 f to 156 f). Panels are sandwich constructions, but fanges are solid (un- cored) to optimize assembly by adhesive bonding and mechanical fastening. Larger, 75-mm/3-inch thick fanges are used where panels are bolted to the hull's steel fanges (see computer rendering). Mul- tiaxial fabric from Owens Corning (Toledo, Ohio) forms the face- skins, over a polyvinyl chloride (PVC) Divinycell H80, 32-mm/1.3- inch thick core supplied by DIAB International (Laholm, Sweden). Te core is grooved by Barracuda in a proprietary manner that Nasseh says improves infusion fow. Te resin is an orthopolyester formulated by Ashland Performance Materials (Columbus, Ohio). He adds that the infusion process was modeled prior to fnalization of the design using Polyworx sofware from Polyworx (Nijverdal, Te Netherlands). To meet transportation requirements, each panel is overcoated with an Ashland fre-retardant polyester. "Te new composite design will allow overall weight reduction, fuel economy, less maintenance cost," says Nasseh, "and ofers a bet- ter cosmetic design." power microgrid on the ground (Altaeros estimates the remote power and microgrid market at $17 billion per annum). Altaeros cofounder/CEO Ben Glass says the BAT prototype uses a small Sky- stream turbine, from XZERES Wind Corp. (Wilsonville, Ore.), with carbon fber composite blades made by the University of Maine's Ad- vanced Structures and Composites Center (Orono, Maine). Altae- ros, however, replaced the turbine's aluminum nacelle with one made in-house to reduce turbine weight, says Glass, using a sandwich con- struction of three-ply carbon fber skins over an aramid honeycomb core. "BAT is a low-cost power solution … that can power more than a dozen homes," explains Glass, and can be transported easily and set up without the need for a crane. In 2013, Altaeros successfully tested a proof-of-concept BAT in 45-mph/72-kmh winds and at a height of 500 f/152.4m in Maine, and is currently working on rotor and nacelle designs for commercial-scale BAT deployments. Te frst product will have about 30 kW of capacity, slightly larg- er than the prototype, followed by scaled up products in the 100- to 200-kW range. Far from the power grid, remote settlements pay dearly for elec- tricity. In Alaska, for example, the cost of energy from diesel genera- tors reportedly can reach $1/kW-hr (compared to $0.10/kW-hr or less for coal-, natural gas- or wind-sourced energy in the lower 48 states of the U.S.). Altaeros Energies (Boston, Mass.) aims to change that. A spin-of from the Massachusetts Institute of Technology (Cambridge, Mass.), the startup's lighter-than-air Buoyant Airborne Turbine (BAT), can harvest the more consistent winds at higher alti- tudes because its elevation is not limited by the need for a tower. A $1.3 million (USD), 18-month demonstration project, partially funded by the Alaska Energy Authority's Emerging Energy Technology Fund, is set, at a site south of Fairbanks, to break a world record as the highest wind turbine ever deployed — 1,000 f/308m. Adapted from aerostats (blimps) that have long lifed heavy communications and weather equipment skyward, the BAT consists of a helium-flled infatable shell surrounding a turbine. High-strength tethers do double-duty, holding the BAT steady and transporting electricity to a Source (both photos): Barracuda Source: Altaeros 0614CT Applications-OK.indd 38 5/20/2014 8:52:36 AM