Marine Energy Innovation: Insights from Verdant Power

Marine Energy Innovation: Insights from Verdant Power

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Editor’s Note: NHA and Marine Renewables Canada are hosting a Virtual Event  on June 8th for World Oceans Day, focusing on advancements in the marine energy sector. Marine energy has made great progress over the last year, and we’ll be highlighting achievements, discussing potential opportunities, challenges, and how we’ll meet the end goal of accelerating growth in the sector.

Marine energy leader Verdant Power developed the first commercially licensed tidal power project in the United States, generating clean energy from the natural tidal currents of New York City’s East River. Agreeing to an interview with the National Hydropower Association’s POWERHOUSE media platform, Verdant Power wants to share exclusive insight into its experience developing a marine energy project, the technology at play, the results of the work, and what comes next.

Other organizations considering expansion into wave energy generation, or for those fascinated by innovation, stand to learn from Verdant’s pioneering work in the marine energy sector.


The Roosevelt Island Tidal Energy (RITE) Project was located in the East Channel of the East River, a tidal strait connecting Long Island Sound with the Atlantic Ocean in New York Harbor. During nine months of continuous operation in 2020 and 2021, Verdant’s tidal power system delivered more than 300 megawatt-hours of electric energy to the New York City grid—a record for marine energy production in the United States.

As this video shows, the three-turbine Roosevelt Island Tidal Energy Project enabled commercial scale-up, having established both environmental compatibility and investor confidence.

Verdant is also working on a larger marine energy project, which is currently underway in Long Island Sound. The technology developer plans on scaling up its work with the goal of producing hundreds of megawatts of clean power. In turn, the energy generated will go toward supporting New York State’s goal of 70% renewable energy by 2030.


Founded in 2000, Verdant Power LLC commercialized tidal energy to realize the blue economy powered by the marine renewable energy industry. Verdant has advanced the performance and reliability of its tidal power system from the first operating multiturbine tidal array in New York City in 2006-2009 to the first U.S. Federal Energy Regulatory Commission (FERC) tidal pilot project license issued for the Roosevelt Island Tidal Energy Project in 2012, then to the project’s culminating installation, operation, and demonstrated maintenance cycle from 2020-2021.

Awash in firsts, the Roosevelt Island Tidal Energy Project was licensed under the first FERC hydrokinetic pilot project license issued in January 2012 after a four-year consent process,  including a water quality certification from the New York State Department of Environmental Conservation. Verdant Power also received the world’s first International Electrotechnical Commission (IEC)  standard performance assessment and Renewable Energy Test Report (RETR) for marine energy. Conducted by the European Marine Energy Centre (EMEC), it is  also EMEC’s first ISO/IEC 17025 accredited power performance assessment at a site outside the center’s test facilities in Orkney, Scotland. Verdant Power is also a 2021 winner of NHA’S Outstanding Stewards of America’s Water (OSAW) award.

Following six years of studies, the FERC pilot operating license granted in January 2012 for a 10-year project was fundamental to Verdant’s operational success. The initial overriding regulatory challenge was the lack of a process for hydrokinetic energy in 2005, and the lack of scientific studies and analysis to assess effects of an operating array.


 The Roosevelt Island Tidal Energy project utilized Verdant Power’s Free Flow System (FFS), a turnkey water-to-wire system utilizing horizontal-axis turbines to convert the kinetic energy of fast-moving (> 1.8 meters per second) water currents into clean renewable electricity. Three turbines were deployed on Verdant Power’s TriFrame mount on the river bottom, fully underwater and not visible from the surface.

The three-turbine project enabled commercial scale-up, having established both environmental compatibility and investor confidence. With an installed rated capacity of 210 kW, turbines were installed at a depth of 10 meters. The turbine systems exceeded every performance goal with approximately 40% more energy and near 100% availability, proving the system’s commercial readiness.

A key goal was to advance the system’s technology readiness level (TRL) toward a commercial level. Verdant has now achieved the technology readiness level 8 by demonstrating a commercial type system in the relevant environment. At the Roosevelt Island Tidal Energy Project, the technology was advanced through three distinct phases:

  1. Proof of concept demonstration – the 2006-2009 RITE “six-pack”- the first multiturbine grid-connected marine energy array
  2. Key component and subsystem design and testing in 2012-2019 to protocols and demonstrating design and reliability
  3. The 2018-2021 system advancement at full scale to TRL 8 commercial readiness

Commercialization required economic goals, which were achieved. By utilizing an integrated design process to reduce both capital expenditures and operating expenditures of on-water work, the levelized cost of marine energy makes it competitive with other renewables. Operational excellence at Roosevelt Island Tidal Energy put the vision of commercial projects at larger scale within reach.


NHA’s POWERHOUSE (PH) talked with Verdant Power (VP) about lessons learned at the Roosevelt Island Tidal Energy Project, the future of its Long Island Sound project, and what’s next for marine energy.

POWERHOUSE: As the country’s first commercially licensed tidal power project, what were the top challenge(s) to achieve licensing? Considering the “Catch-22” challenges, what would you do differently in the future?

Verdant Power: The earliest challenge was the broad federal, state and local hydropower regulatory community’s lack of experience with innovative in-water technologies and defining proportional risks. The critical initial concern was fish impact from the turbines. Through the deployment of underwater hydro-acoustics monitoring and videoing fish movement around the turbines, regulators were able to observe the minimal fish impact from the turbines. The deployment and operation of the RITE Project six-turbine array from 2007-2009 assisted the regulators in redefining the turbine and project risk. [The Federal Energy Regulatory Committee’s hydrokinetic pilot license was awarded with the condition that any significant environmental impact would stop the turbines and the project until effectively addressed in contrast to a hydropower dam license. Verdant Power worked with Oak Ridge National Laboratory fisheries experts to collaborate with the fishery’s regulatory community. At this point, the minimal fish and other impacts have been demonstrated, so in the future we have a base of experience and results to work with the regulators for future projects.

PH: How did the New York State Department of Environmental Conservation partnership benefit Verdant Power, especially the Renewable Optimization and Energy Storage innovation program?

VP: Initial New York State Department of Environmental Conservation grant funding of $500,000 launched the RITE Project in 2002. Verdant Power was awarded eight New York State Department of Environmental Conservation technology and environmental grants for approximately $5 million over ten years to support the RITE Project. All of Verdant’s grants were prior to the Renewable Optimization and Energy Storage innovation program.

PH: Beyond the energy supply or New York State Department of Environmental Conservation, Verdant Power credits all the partners working together, including Kleinschmidt Associates, U.S. Department of Energy, and 100-plus supply chain vendors and marine contractors. How critical were the partnering efforts?

VP: From its inception, Verdant Power has been a company with few employees and consultants so experienced partners have been critical from the beginning. Partnering companies and consultants in regulation, design, manufacturing, testing, technical standards, and marine and utility operations have been critical to success of the RITE Project in proving and certifying Verdant Power system performance. Verdant Power partners included companies from across the United States as well as European companies.

PH: Overall, what are the top benefits of the TriFrame Mounting System, the Free Flow System (FFS), and the Kinetic Hydropower System? What was unique – the main differentiator in Verdant Power’s technology vs. competitors?

VP: The Free Flow System Kinetic Hydropower System is a rugged, reliable and efficient open turbine that concerts the energy in naturally flowing water into electricity, or other energy storage means such as hydrogen, with predictability and maximum compatibility with the natural environment. It is designed to be far simpler than other turbines, with the sophisticated design in its shape, and no complex systems, so it is more dependable and requires a minimum of maintenance. The TriFrame mount provides a cost-effective support for three turbines from a single structure requiring no civil works on the seafloor. The TriFrame is quickly installed and can be completely removed with minimal impact.

PH: The fundamental technology challenges were concurrent with the highly energetic marine environment while proving efficiency, reliability and survivability that will scale to commercial projects. The RITE Project met and exceeded all of these goals with the successful installation, operation, and retrieve and replace maintenance cycle. What would you change – or not change – for future projects?

VP: The RITE Project test site was limited by its depth to 5m diameter turbines. While this scale is fully representative of the larger, commercial scale of 10m and larger, our next step is a 12m diameter version of the turbine system. The TriFrame will similarly be scaled up to support the larger turbines, and there will additionally be some operational differences for the larger system. The Gen5 systems evaluated at RITE were the most recent evolution of the system, and thus performed with excellent efficiency and reliability. For the 12m turbines, there will be some necessary differences for installation and retrieval operations, and some detailed refinements to maximize longevity based on Verdant’s experience at the 5m level.

PH: Since deployment in October 2020, Verdant Power’s 5th generation tidal power turbine system has delivered electricity to NYC’s distribution grid, exceeding 295MWh generated as of July 8, 2021. What is an updated statistic?

VP: The TriFrame was tested from October 2020 until October 2021, with a planned retrieve and replace operation in May 2021 after 6 months of operation, termed Period A. As planned, during the 36-hour retrieve and replace, one turbine was removed and replaced by a fourth turbine to demonstrate and measure the time and cost of the maintenance operation. The fourth turbine was identical except the blades were made by National Renewable Energy Laboratory of a new thermoplastic material to test its behavior. The reinstalled turbines continued operation for Period B of 300 tides. Altogether, the turbines were operated from October 29, 2020, through July 23, 2021. Over the total 1,030 tides, or 267 days of operation, (including the retrieve and release outage) the 210 kW rated system generated 312 MWh, an average of 1.27 MWh/day, or 427 MWh per year. This performance of energy into the grid exceeded Verdant’s minimum requirement by over 40%.

PH: Overall, realizing the project’s massive technical content and achievements, what stands out as the greatest technical challenge(s) and accomplishments?

VP: The greatest innovation was the structural design and operational design of the TriFrame mount system, which will enable commercially viable installation and operation of the turbines. The demonstrated and quantified success of the on-water operations to professionally install and remove the TriFrame twice, and its excellent stability on the river bottom, helps prove the viability of this approach to lower costs. Meanwhile, the official validation to International Electrotechnical Commission power performance standards by the European Marine Energy Centre of the excellent performance of the turbine systems was a world’s first.

PH: How does the project help achieve New York state’s goals of 70 percent renewable energy by 2030?

VP: The RITE Project was a system demonstration that will not contribute to the state’s goals. A much larger project that we are planning for is the Long Island Sound, which will provide hundreds of megawatts of reliable and predictable power to New York State’s goals.

PH: Looking back over the past twenty years, what overall has that time taught you?

VP: The past twenty years of technology and operation development has borne out our basic philosophy that for cost-effective commercial operation, kinetic hydropower systems must not only be efficient, but especially simple, rugged, and reliable.

PH: Looking ahead, what do the upcoming twenty years look like for marine energy?

VP: Marine renewable energy and its contribution to clean energy is on the verge of exponential growth, especially in nations with sizable offshore resources and the political will to help markets emerge. In twenty years, there will be many gigawatts of marine renewable energy, with tidal the leader in predictability and major grid support, in addition to replacing diesel power in smaller communities around the world.