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By Dawn Killough
July 13, 2017
A new offshore wind farm near the coast of Rhode Island may hold the key to the US’s journey to energy independence. It officially started production in early May, after a four-month testing phase and several months of construction. The logistics and technology used to install these five wind-powered turbines is interesting to see.
GE and Deepwater Wind, a developer of offshore turbines, partnered to build five massive wind turbines and install them in the Atlantic Ocean. They make up the first offshore wind farm in North America, called the Block Island Wind Farm. The farm has already generated enough power to effectively shut down the diesel power-generation plant that previously provided power to Block Island.
The wind farm is rated at 30 megawatts, which is the amount of power required to power every home on Block Island, says the farm's project manager, Eric Crucerey. It will emit about 40,000 fewer tons of greenhouse gases per year than fossil fuels would for the same amount of energy. That's the equivalent of taking 150,000 cars off the road.
Installation of the turbines 30 miles off the coast of Rhode Island began in 2015, and construction was complete in late August 2016. The farm's four-month testing phase, which produced more than one gigawatt-hour of electricity, ended on December 2, 2016. The system went live on May 3, 2017.
Offshore wind power is more efficient and produces more power due to the almost-constant wind found out in the ocean away from land. Windmills can be built at a larger scale offshore, which allows them to generate more power also. Because of this, these farms may hold the key to the US’s future energy independence.
The equipment and logistics utilized to construct these behemoth windmills (they stand at approximately 600 feet, almost twice the height of the Statue of Liberty) is amazing and awe-inspiring.
The parts and pieces for each windmill came from various locations around the world. The windmill blades were manufactured in Denmark, and had to be trucked to a dock so they could make the ocean voyage across the Atlantic. Special trucks, and roads, were used to transport them over land. If the trucks wouldn’t be properly supported or couldn’t navigate the existing roads, new temporary ones were built just to transport the blades.
The nacelles (the covers that protect and encase the internal workings of the windmill generators) were manufactured in a GE plant in St. Nazire, France. They traveled across the Atlantic on ships specially constructed to keep the nacelles off the deck, so waves could crash across the ship without damaging them.
The 95 feet tall tower portions of the windmills came by boat from Aviles, Spain. Each tower holds the 400-ton power-generating nacelle, a machine as large as a school bus, and three blades that weigh 27 tons each. The generator is split into three separate electrical circuits so that even if two circuits go offline, the turbine can still produce two megawatts of electricity on the remaining circuit.
Bright yellow foundation bases were constructed to hold the windmill structures. The bases are pile-anchored to the sea floor. They have to be extremely strong, as the windmills are structurally engineered to handle a category-3 storm. Each of the four, five-foot wide steel piles were driven to secure the foundation.
Next, 56-foot tall deck platforms were installed on top of the foundations. All the decks were welded to the top section of the steel jacket foundations 13-feet above the waterline and stand 69 feet above the surface of the Atlantic Ocean.
Deepwater Wind spokesperson Meaghan Wims was asked if it would be easier if the foundation components were installed in the water with the deck platforms already attached to the foundations as one singular component. “It would not be an easier installation process,” said Wims. “With a one-piece foundation, the piles are more difficult to install, requiring underwater pile driving and pile grouting, two techniques that we determined were less optimal than above-water pile driving with a two-piece foundation.”
Construction teams used a special ship to help with the raising of the towers, generators, and blades. The L/B Robert, built by Montco, is like a small floating city, containing four cranes, a self-elevating hull, three 335-foot long legs and the ability to rise 240 feet above sea level at a maximum working water depth of 280 feet. Ships carrying the parts for installation were hoisted up to the level of the Robert, and materials were offloaded and moved into place using its giant cranes.
While construction activity was going on, Deepwater Wind stressed the importance of protective measures designed to minimize the potential impact on North Atlantic right whales and other marine mammals. They signed an agreement in May 2014 with a coalition of leading environmental and conservation organizations, including the National Wildlife Federation, Natural Resources Defense Council, and the Conservation Law Foundation, to implement protective measures.
“All pile driving was done under a set of strict rules designed to avoid harming sensitive marine species, especially endangered whales like the North Atlantic right whale and the humpback whale,” said Wims. “We are pleased to report that the work was completed without any harm to the environment or marine species.” In fact, some reported that a whale was seen around the wind farm site while construction was going on.
It appears that offshore wind power could be the next great advancement in renewable energy. It’s clean, can be built without harming the environment, and is in almost endless supply. As generation technology gets better, power capacities will only go up.
The potential for US offshore energy is quite large––over 4,000 gigawatts (GW)––which amounts to more than four times the nation’s annual electricity production, according to the US Department of Energy.
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