Free Flow System
Verdant Power’s Free Flow System (FFS)* is a turnkey water-to-wire system utilizing horizontal-axis turbines to convert the kinetic energy of fast-moving (> 1.8 m/s) water currents into clean renewable electricity. Multiple turbines are deployed on TriFrame™ mounts in a field array fully underwater and not visible from the surface.
Free Flow System Turbine
The central component of the Verdant Power Free Flow System is a three-bladed horizontal-axis turbine. The turbine is equipped with a composite rotor with three fixed-pitch blades that rotate at a slow and regular rate (approx. 32 rpm). This is well below normal water vessel propeller speeds and conventional hydropower turbine blade speeds.
The drivetrain and generator are enclosed within the nacelle, including a special integrated long-life planetary gearbox and bearing housing with mechanical shaft seals for the main shaft. The sealed nacelle is supported on a pylon that attaches to a seafloor mount, which can vary depending on site and project specifications.
Simple and Scalable: A key advantage of the FFS turbine is its simplicity -- the unit is ‘ready for operation’ almost as soon as it is deployed. The turbines include no hydraulic systems and rotate to generate energy as long as there is adequate water speed (> 1.8 m/s). The turbines operate continually and automatically, and are remotely monitored by a proprietary control system, with local operating technicians checking conditions at a shore-based control room on a routine and, if necessary, outage basis.
Verdant Power's TriFrame™ is a steel, triangular frame mount that supports three Free Flow System turbines. An array of multiple turbines on TriFrames is arranged at a project site based on water velocity, hydrodynamics, and accessibility.
Array Maintenance: Retrieve and Replace (R&R): A key advantage of the TriFrame™ is that multiple turbines can be accessed through one on-water operation. To minimize outage time and high costs of on-water work, the evolving TriFrame™ maintenance strategy is a retrieve and replace (R&R) cycle, meaning the retrieval and immediate replacement of turbines with ready spares. The retrieved turbines are then refurbished at a local land-based facility for subsequent reuse.
TriFrame™ allows for installation and R&R access to multiple turbines in single on-water operations, minimizing related time and high costs.
R&R cycle strategy allows for regularly scheduled on-water operations and maintenance work, lowering the levelized cost of energy (LCOE) and reducing risks for unplanned outages.
Coupled with the simple design of the Free Flow System turbine, use of local facilities for refurbishment can return turbines to readiness and into a spare fleet within days.
Refurbishment work can usually be accomplished in the community surrounding the project, creating local economic benefits.
Gen5 Free Flow System Turbine
Tidal and River Operation: The Free Flow System is highly adaptable and can be operated in both tidal settings, wherein turbines yaw to capture energy on both ebb and flood tides, as well as rivers, in which uni-directional turbines generate in the steady flow of the river current.
Adaptability: Beyond operation in both tidal and river settings, FFS turbines can also be scaled to different sizes and arrayed in various configurations, allowing for the following usages:
Village- to Utility-Scale Grid Power
Deep Offshore to Shallower Nearshore Waters
Hybrid power systems (microgrid baseload power)
Integrated energy and clean water systems
Direct power to in-water/onshore facilities and equipment (e.g. data centers, ROVs)
Rugged and Resilient: The Free Flow System is designed for simplicity, reliability, and ruggedness to extend service life and minimize O&M costs. Additionally, placement underwater enhances resiliency to severe weather events.
Highly Predictable: Tidal and river currents are highly predictable, with resource availability predictable years into the future. This allows for long-term energy delivery planning and differs from variable renewable energy resources such as wind and solar, which are predictable only on a short-term basis.
Water-Energy Nexus: The in-water siting of the Free Flow System (and associated resource assessment activities conducted during project development) creates opportunities to develop integrated approaches to water-energy issues traditionally managed separately. More >
* - Free Flow System is also referred to as the Kinetic Hydropower System (KHPS) in some technical and regulatory documents.