Turning Tides: Innovative Tidal Power Plant to Energize Remote Island Grid

February 19, 2024 by Shannon Cuthrell

A bi-directional turbine system will harness ocean tides to power a remote island grid in the Philippines.

A 1 MW tidal energy project will tap the strong currents of the remote Philippine island of Capul to displace a 750 kW diesel power plant. The installation, featuring a gravity-optimized base with bidirectional turbines and a unique active pitch system, is expected to come online in late 2025 as Southeast Asia’s first tidal power generation plant. 

U.K.-based Inyanga Marine Energy Group will lead engineering, procurement, and construction, supplying its HydroWing bi-directional tidal turbine system. The first development stage will connect a microgrid network with solar panels and an onshore energy storage facility, enabling 24/7 power from the turbines linked to Capul’s electrical network. 


A rendering of HydroWing’s installation.

A rendering of HydroWing’s installation. Image used courtesy of Tocardo


The microgrid will provide power generation and distribution services for the island’s population of more than 12,300. According to the latest estimates from the Philippines Department of Energy, Capul consumed about 1.36 GWh of energy in 2020. Its power comes from diesel generators, which only supply eight to 16 hours of energy daily and experience regular blackouts. The project’s developer, Energies PH, stated the Capul Diesel Power Plant had a peak demand of 427 kW in 2022. At one point in 2019, there were 35 outages in a single month, totaling 33 hours between July and August. 


Location of the Capul tidal energy project.

Location of the Capul tidal energy project. Image used courtesy of Energies PH (Page 7)


Philippines-based developer Energies PH leads the project through its affiliate, San Bernardino Ocean Power Corporation. The company plans to replicate its tidal wave concept at several remote sites across the Philippines, adding new renewable capacity in the hinterlands. 


Why Tidal Energy?

Tidal energy technology harnesses the natural ebb and flow of water pulled by the earth, sun, and moon’s gravitational fields. Geographical features like inlets, straights, headlands, or narrow channels can intensify tidal currents in certain sites. This is the case with Capul Island’s proximity to the San Bernardino Straight, a narrow passage on the northeast side of the Philippine archipelago. In spring tides, currents in the straight exceed three meters per second (or about 3.2 feet), offering an estimated potential of 500 MW from tidal stream energy. 

In addition to supplying carbon-free power supporting renewable targets, tidal energy systems boast a high power output and predictable generation. Installations are often paired with battery energy storage systems that can be tapped for peak demand or backup power. 

While technically promising, tidal energy technology faces challenges constraining its economic competitiveness. Inyanga’s HydroWing system addresses two critical limitations by eliminating costly offshore maintenance—which typically requires dispatching specialized vessels—and reducing the complexity of competing products, focusing on increasing output by optimizing tidal energy extraction to the disadvantage of device reliability. 


The HydroWing system.

The HydroWing system. Image used courtesy of Tocardo


HydroWing’s multi-rotor device has two primary components that the company claims minimize capital expenses and boost reliable power generation. 

  1. The permanent gravity-based support structure is designed to distribute loads evenly from the turbines, lessening fatigue. 
  2. The setup features one to three retrievable wings with two to five turbines ranging from 100 to 200 kW each. The turbines’ 16- to 32-foot diameter minimizes wake effects and increases power density. 


Inyanga’s Quad Hull Barge

Inyanga’s Quad Hull Barge. Image used courtesy of Inyanga Marine Energy Group


Inyanga’s Quad Hull Barge eases HydroWing’s installation and maintenance costs. The vessel locks the load after lifting it to the gantry arch, unlike the typical design, which places the load onto the deck with minimal overhang. 


HydroWing’s Bi-Directional Blades and Passive Pitch System

HydroWing uses bidirectional blades from Tocardo, a Dutch tidal energy technology developer. The turbines incorporate a passive pitch control system that boosts efficiency by pitching 180 degrees toward the incoming tide when flows are high. This approach reduces loads and leaves room for larger blades with a 50% higher yield. 

Tocardo’s T3 turbines use a direct drive generator with variable speed, enabling operation in a wide range of water speeds as tides enter and exit. The next-generation version doubles the power of the predecessor T2 design. Its passive pitch system harnesses the tide’s force to twist the blade based on the incoming flow. In contrast, conventional active pitch mechanisms must be continuously adjusted to maximize power extraction in the mean flow speed over the tidal period. The mechanical complexity of active pitch controls often necessitates additional maintenance. 

HydroWing’s passive pitch method decreases the forces induced, doubling the power without raising loads. At the same time, the bi-blade design broadens the dimensions while shedding pitch at higher loads. 


Video used courtesy of HydroWing


The Capul Island project will install an instantaneous subsea electrical connector, export cable, and centralized control hub. The smart rotor and bi-directional blades guarantee a 20-year lifespan by eliminating the typical wear and tear of a gearbox and mechanical pitch component.