By Christian Roselund
Last Thursday, workers using a boat-mounted crane secured the final 240-foot blade onto a massive wind turbine, anchored to the ocean floor beneath Long Island Sound. With this act the turbine, and four others like it, were completed off the coast of a small island in the sound, known to locals as a tourist destination.
Together, the five turbines at the Block Island Wind Farm have a capacity of 30 MW, and when they begin spinning in roughly two months’ time are expected to supply enough power to meet the island’s electricity needs nine times over. Through a power contract, developer Deepwater Wind will not only supply power for Block Island’s 1,051 residents and seasonal tourists, but will send the large majority to the mainland of Rhode Island.
This is the first offshore wind farm in the United States, and it is not expected to be the last.
Offshore wind has been supplying power to Europe for decades, with the first offshore wind farm built off the coast of Denmark in 1991. The industry has followed the typical deployment curves of emerging renewable energy technologies, and has moved from a global cumulative capacity of 32 megawatts in 2000 to nearly 12,000 megawatts at the beginning of this year, with nearly all of that capacity located in European waters.
Offshore wind has lagged in the United States. Despite initial siting approval from the state of Massachusetts in 2005, the ambitious 454 MW Cape Wind project has still not broken ground eleven years later, due to local opposition including multiple lawsuits backed by the Koch Brothers and other affluent and powerful residents of Cape Cod and Nantucket Island.
But where the Cape has proved unfriendly for offshore wind, Rhode Island has welcomed the industry with open arms. In an interview with CleanTechnica, Deepwater Wind CEO Jeffrey Grybowski cited state support of the project as the primary reason why the first offshore wind farm has been built in Rhode Island waters.
Dollars and sense
One reason for the slower deployment of offshore wind in the United States has been the price, given that the United States generally has lower retail electricity prices than Europe. Cape Wind initially held a power purchase agreement for $0.207 per kilowatt-hour — around the price of Massachusetts retail electricity prices, and much higher than the cost of land-based wind contracts in New England, let alone conventional generation.
But while it holds true globally that offshore wind is often more expensive than other forms of generation, for certain locations it can be less expensive than what is available. Block Island is 13 miles from the coast of the state of Rhode Island, and before this, the island had no electrical connection to North American power grids. Like the vast majority of remote islands, it is entirely dependent upon imported liquid fossil fuels for its electricity generation.
For Block Island, this means importing around a million gallons of diesel fuel by ferry each year to burn in generators. In its latest analysis of electricity generation costs, power consultancy Lazard puts diesel generation at $0.212-0.282 per kilowatt-hour and Grybowski estimates that the retail cost of electricity on the island has reached as high as $0.50 per kilowatt-hour in the last few years — more than twice as high as on the mainland.
As such, offshore wind, like other forms of renewable energy, can be more of a bargain for islands and other remote locations not served by the electricity grid.
The economics of both offshore and land-based wind have also been improved by new classes of larger and more efficient turbines. The Block Island Wind Farm features GE Haliade 150 6-MW turbines, which rise 330 feet from the ocean and were the largest turbines available when Deepwater Wind contracted for them.
“You are converting more wind to usable energy as these turbines are coming more efficient,” Grybowski told CleanTechnica. “The larger machines allow you to capture more energy from the air, but then again you need a really great wind resource to take advantage of these really large machines.”
However, raw delivery of electricity is not the only factor in judging the output of renewable energy. Two other factors must be considered — when this electricity is generated, and how steady and predictable the output is.
The economics of solar electric technologies are enhanced in hot and/or industrialized regions where daytime power demand is high, particularly in the summer. The opposite is true for land-based wind, which in many geographies tends to produce more power at night when demand and prices are low. Grybowski notes that the winds off of Block Island are most intense in the afternoon and early evening, which roughly meets the demands of peak power for tourist areas with little air conditioning or industry.
Locating wind turbines offshore also has the advantage of steadier supply of power. Capacity factors — a measure of how much electricity is generated over a given time period as measured against the total capacity — for wind turbines have increased in recent years. But while the average capacity factor for onshore wind in the United States was only 33% in 2014, Deepwater Wind forecasts that the Block Island Wind Farm will have a capacity factor of 47%.
These two factors — the higher capacity factor, and the afternoon and evening output — could make offshore wind a key resource for meeting energy needs in New England and other regions where peak demand for the combination of heat and electricity, and thus peak gas prices, comes in the evening after the sun goes down.
Taking to the sea
30 MW is not terribly large for a wind farm, and is tiny compared to many coal, gas, or nuclear power plants. However, Deepwater Wind is developing a 15-turbine, 90 MW project off the coast of Long Island, and is planning a 200-turbine, 1,000 MW project in New Jersey waters in partnership with utility PSEG.
The South Fork Wind Farm near Long Island is farther along, and the Long Island Power Authority is currently evaluating a power purchase agreement for this project.
Deepwater Wind expects these projects to have lower costs than the $0.24 per kilowatt-hour power contract signed for Block Island. “Small projects are more expensive, while larger projects that reach the sweet spot of size — 100, 200, 300 megawatts — tend to have much lower cost points,” explains Grybowski.
Grybowski estimates that current contract prices for offshore wind in Europe are around $0.11 per kilowatt-hour, and says that he expects similar prices in the United States as more and larger projects are built. “I think mid-to-low teens is achievable in the U.S. in the near term,” Grybowski told CleanTechnica.
However, Grybowski also notes that building an initial smaller project was a strategic choice for both Deepwater Wind and the state of Rhode Island. “It is difficult in a new industry to start at a very large scale,” he notes. “There are significant risks involved, and many of the stakeholders don’t have the confidence to support a very large project. We always believed that starting with a small project was critical in order to have a success for the industry.”
Even a 1,000 MW project is still a very small portion of the addressable capacity. The U.S. Department of Energy estimates that there is the potential to build 4,000 GW, or 4,000 such projects, off the coasts of the United States and the Great Lakes.
Some states are moving to tap that potential. Massachusetts’ omnibus energy bill signed earlier this month mandates that the state’s utilities procure electricity from 1.6 GW of offshore wind projects by 2027. However, following the failure of Cape Wind, so far that is only a number. In Rhode Island there is actual steel in the water.
Grybowski is confident about the future of the U.S. offshore wind industry. “With this success of the Block Island project, we are confident that we collectively in the U.S. we will be able to move to progressively larger and larger projects over time,” he states. “But none of that would be possible without Block Island being successfully built and operated.”