- What it is: AR1100 is a 1.1‑MW, three‑bladed, horizontal‑axis tidal turbine from Proteus Marine Renewables (PMR). It uses electromechanical pitch and yaw control, a permanent‑magnet generator, sits on a gravity base, and sends power ashore via subsea cable. Marine Technology News
- Where: Naru Strait between Naru Island and Hisaka Island in the Gotō Islands (Nagasaki Prefecture)—a government‑designated marine renewables test field with peak currents >3.0 m/s. q-mirai.co.jp
- Who’s behind it: Turbine by Proteus Marine Renewables; project owner and grid interface by Kyuden Mirai Energy (KME); program backed by Japan’s Ministry of the Environment (MOE); installation contractor Toyo Construction. proteusmr.com
- Timeline: Turbine installed February 2025; passed pre‑use inspection under Japan’s Electricity Business Act on May 23, 2025; METI certification issued June 2, 2025; now exporting power to the grid. q-mirai.co.jp
- Why it matters: It’s Japan’s first megawatt‑scale, grid‑connected tidal unit—a national milestone for dispatch‑predictable ocean energy. Marine Technology News
- Upgrade path: The AR1100 upgrades the site’s earlier AR500 (500 kW) pilot that achieved 97% turbine availability and produced 247 MWh in 2021. proteusmr.com
- Expected output: Local estimates suggest ~2.41 GWh/year (≈ 800 households) at Naru—about a ~25% capacity factor for a 1.1‑MW rating. (Calc from the Toyo figure.) toyo-const.co.jp
- Blades & materials: Composite blades ~7.7 m long (max chord ~1.9 m) designed for high loads and fatigue life in tidal streams. JEC
The in‑depth roundup
1) The headline milestone: Japan’s first MW‑class tidal power to the grid
On February 2025, Proteus Marine Renewables installed the AR1100 in the fast‑flowing Naru Strait off the Gotō Islands. After commissioning and compliance testing, Japan’s Ministry of Economy, Trade and Industry (METI) certified the system on June 2, 2025, clearing it to export power to the national grid—marking Japan’s first megawatt‑scale, grid‑connected tidal generator. proteusmr.com
2) Why Naru Strait? Site physics + national policy
The Naru Strait funnels strong, predictable tidal currents, routinely exceeding 3 m/s at the demonstration zone—one reason the site is designated a national marine renewable energy test field. Predictability is tidal’s superpower: output can be forecast years ahead using tidal harmonics, easing integration compared with weather‑led wind and solar. The AR1100 project sits inside the MOE’s “Regional Decarbonization Model via Tidal Power” (FY2022–2025) program, with a planned budget of ¥2.6 billion for Phase 2 activities. q-mirai.co.jp
3) The machine: how AR1100 works (and what’s new)
AR1100 is a seabed‑mounted, horizontal‑axis tidal turbine. Its three composite blades change angle via electromechanical pitch to maximize capture and shed loads; a yaw system turns the nacelle so the rotor always faces the reversing tide. Mechanical power is converted in a permanent‑magnet generator and shipped ashore through a subsea export cable to onshore power electronics for grid distribution. The gravity‑base support enables installation and retrieval without piling. These features are a direct upgrade from the site’s earlier AR500, adding pitch and yaw and uprating to 1.1 MW. Marine Technology News
Blade engineering. The ~7.7 m blades (max chord ~1.9 m) use high‑strength composites for fatigue resistance in dense seawater flows. Shorter, stubbier tidal blades see root loads comparable to much larger wind blades; materials and aero‑hydrodynamics are tailored accordingly. JEC
4) From pilot to power plant: the AR500 → AR1100 journey
Japan’s tidal chapter began here in 2021 with the AR500 pilot, which ran at 97% turbine availability and generated 247 MWh by year‑end—valuable operating data that derisked the site and supply chain. Building on that, Kyuden Mirai Energy (KME) contracted an upgrade for Phase 2: adding pitch/yaw, uprating the drivetrain to 1.1 MW, and re‑using the subsea foundation and cable route. Ocean Energy Europe
5) Certification, grid export and operations
After installation in February, the project passed the pre‑use inspection under the Electricity Business Act on May 23, 2025, then secured METI certification on June 2, 2025—confirmation that the plant meets national safety, grid‑code, and emergency response requirements. With that, the turbine began exporting power into the Gotō/Kyushu grid. q-mirai.co.jp
6) How much energy and who benefits?
Toyo Construction, which led the heavy‑lift and installation (using its DP crane vessel AUGUST EXPLORER), cites an expected ~2.41 GWh/year—roughly 800 households worth of electricity—once steady operations are established. For a 1.1‑MW nameplate, that pencils out to a ~25% capacity factor, consistent with high‑energy tidal straits. The predictability of tidal windows also supports local grid planning on the islands. toyo-const.co.jp
7) The project team and local supply chain
- Owner / grid lead: Kyuden Mirai Energy (KME), prime contractor to MOE’s decarbonization program at Naru Strait. q-mirai.co.jp
- Turbine tech & offshore services: Proteus Marine Renewables (UK) and its Japan unit Proteus Operations Japan. proteusmr.com
- Heavy marine works: Toyo Construction (Japan), leading retrieval/installation and local marine operations. toyo-const.co.jp
8) Materials & design notes that matter
Tidal turbines operate in high‑density fluid (seawater), so blade root loads and fatigue cycles are intense. Carbon/resin composite blades deliver the required stiffness‑to‑weight and fatigue life while resisting corrosion; failure behaviour also avoids buoyant debris if a tip breaks. Independent pitch allows load relief in gusty flows (eddies) and optimizes capture over each tide; yaw is essential because current direction reverses about four times a day. JEC
9) How it stacks up against Japan’s other marine energy path (Kairyu)
Japan is also advancing ocean‑current power (not tides) with IHI’s “Kairyu”—a floating, deep‑water system that harnesses the Kuroshio Current. Kairyu’s 100‑kW demo completed multi‑year sea trials and aims at ~2‑MW class commercial units in the 2030s. The AR1100 is different: a seabed‑mounted tidal device in a coastal strait with bidirectional flow and known tidal windows, now already exporting power at MW scale. Together they suggest a portfolio approach to ocean energy in Japan. IHI Corporation
10) Risks and real‑world operations
- Tidal windows & weather: Heavy lifts and maintenance must fit slack‑tide windows; Naru’s strong currents demand specialized vessels and procedures—factored into KME’s program schedule. q-mirai.co.jp
- Biofouling & corrosion: Composites mitigate corrosion; smart coatings and planned retrieval cycles manage fouling and inspection. (Industry practice reflected in PMR’s design notes.) proteusmr.com
- Grid integration: METI’s certification process explicitly verified grid compliance, safe shutdown, and emergency response, derisking operation in a remote island grid. proteusmr.com
11) What’s next: scaling from “one turbine” to “tidal power plant”
KME and Proteus say they’re exploring additional capacity in Japan following certification. On Proteus’s roadmap, the AR1100 (Series 2) is a stepping stone to the AR3000—a 3‑MW platform targeted for deployment from 2028 and already tied into a supply‑chain MoU with SKF (rotating equipment) and GE Vernova Power Conversion (electrical systems). If Japan opens more high‑flow straits to similar projects, the Naru playbook—pilot → upgrade → certify → export—offers a template to scale. Energy Global
Specs & program highlights (consolidated)
- Rated power: 1.1 MW (AR1100) • Rotor: 3‑blade, horizontal axis • Blade length: ~7.7 m (composite) • Controls: independent pitch, nacelle yaw • Generator: permanent‑magnet • Support: gravity base • Export: subsea cable to onshore station. Marine Technology News
- Site: Naru Strait, Gotō Islands, Nagasaki (max currents >3 m/s; designated demonstration field). q-mirai.co.jp
- Program: MOE’s Regional Decarbonization Model via Tidal Power (FY2022–2025); budget plan ¥2.6 bn; owner Kyuden Mirai Energy. q-mirai.co.jp
- Compliance milestones: Pre‑use inspection passed May 23, 2025; METI certification June 2, 2025; grid export underway. q-mirai.co.jp
- Pilot pedigree: AR500 at the same site (2021) achieved 97% availability and 247 MWh generation. Ocean Energy Europe
Why this project matters (beyond the headline)
- Dispatch‑predictable renewables: Tidal cycles are known centuries in advance, offering planners a firm, schedulable renewable complement to variable wind/solar. Naru’s certification shows Japan now has a grid‑code pathway for MW‑scale tidal plants. proteusmr.com
- Upgrade‑and‑reuse strategy: Re‑using foundations, cables, and local vessels—from AR500 to AR1100—cuts capex and risk, a repeatable model for other straits. q-mirai.co.jp
- Industrial base forming: The SKF/GE Vernova/Proteus alliance signals maturing tier‑1 supply chains for future multi‑MW arrays—relevant if Japan opens more sites. proteusmr.com
Sources & further reading
- Proteus Marine Renewables — installation and certification releases (device specs, site, grid export). proteusmr.com
- Marine Technology News — technology and installation details. Marine Technology News
- KME (Kyuden Mirai Energy) — official program notes (site, currents, budget, inspections). q-mirai.co.jp
- Toyo Construction — installation overview and expected annual generation. toyo-const.co.jp
- Ocean Energy Europe — AR500 performance (247 MWh) and wider sector context. Ocean Energy Europe
- JEC Composites — blade dimensions and materials. JEC
Bottom line: Japan’s AR1100 is more than a one‑off machine. It demonstrates a certified, grid‑connected, upgradeable tidal architecture in one of the country’s best straits. If replicated, the Naru model could turn strong coastal currents into a reliable, local baseload—and accelerate Japan’s broader decarbonization play.
