Distributed Energy on the Remote Islands of Okinawa

Okinawa Electric Power Co., Inc. Director & General Manager, Remote Islands Energy Services Department Kiyohito Shimabukuro 1. Electric Power Industry on the Remote Islands of Okinawa

・ Okinawa Electric Power Company supplies electricity to 39 inhabited remote islands lying within an approximately 500km radius, through 12 power systems.

Seoul

South Korea Osaka Pusan

Fukuoka Makiminato Thermal Power Miyako No.2 Power Station Tonaki Power Station Station

Shanghai

Ishikawa Thermal Power Station Ishigaki No. 2 Power Station Aguni Power Station 500km

Daito Islands Gushikawa Thermal Power Station Kumejima Power Station Minamidaito Power Station Taipei Okinawa Island Miyako Islands

Taiwan Yaeyama Islands

Tokashiki Power Station Kitadaito Power Station Kin Thermal Power Station

・Electricity is supplied to each of the remote islands mainly through diesel generators. Renewable energy such as wind turbines and sunlight are also being introduced.

Kume Island Aguni Island Ikema Island Miyako Wind Power: Aguni Wind Power 600 kW 18,500 kW Aguni 245 kW Ogami Island 1,680 kW Irabu Island Miyako Island

Kume Island Zamami Island Miyako No. 2 55,000 kW Shimoji Island Miyako Gas Turbine 15,000 kW Aka Island Miyako 19,000 kW Shin-Tarama Miyako Branch 1,86kW Solar Power:10 kW Tokashiki Island Tokashiki Tarama Island Miyako Solar Power ＝＝＝ 4,900 kW Tarama Solar Power: 230 kW Kurima Island 4,000kW4,000 kW Tonaki Island

Tonaki Hatoma Island Ishigaki Island 850 kW Kitadaito Kitadaito Island 1,540 kW Ishigaki Ishigaki No. 2 Yonaguni 20,000 kW 58,000 kW Iriomote Island 3,410 kW Yaeyama Branch Solar Kitadaito Solar Power : 45 kW Power: 10 kW Yonaguni Island Kohama Island Kitadaito No. 2 Solar Power : 90 kW Taketomi Island Ishigaki Gas Turbine Yonaguni Solar Power:150 kW Yonaguni Island Wind Power Kuro Island 1200 KW Ishigaki Island area Hateruma Island Aragusuku Island Minamidaito Island Minamidaito Hateruma Wind Hateruma Minamidaito 3,640 kW ○ Power 950 kW Wind Power ○ 245 kW x 2 245 kW x 2

Challenges for Power Systems on Remote Islands

 Power systems on the remote islands, excluding the main island of Okinawa, are mostly made up of diesel power generators.

 Significant impact from the hike in fuel prices.

 Relatively higher power generation costs.

 High CO２ emissions per unit.

 The power systems are in classes ranging from several hundred kW to several tens of thousands kW.

 Frequency variations resulting from variable power, such as wind and solar power generation, are becoming apparent.

 It is difficult to introduce MW-class wind power generators.

 Due to the scale of the systems, it is difficult to bring in MW-class wind power generators to most of the remote islands.

 It is difficult to bring in large scale heavy equipment (such as cranes) for construction and maintenance. Copyright © The Okinawa Electric Power Company, Incorporated. 4 2. Initiatives for Micro Grids for Remote Islands

[Miyako Island Mega-Solar Demonstration Research] - Maximum electric power on Miyako Island’s power systems: Approx. 55,000 kW - Solar Power Generating Facility: 4,000 kW - Battery facilities NaS batteries: 4,000 kW(28,800 kWh) Lithium-ion batteries: 100 kW(200 kWh)

22kV Power System

Miyako Power Miyako No.2 Power Miyako Gas Turbine Station Station Power Station (Diesel) (Diesel) Miyako No. 6 Wind Power Central control device Sadefune No. 1 and 2 Wind Power 600 kW x 1 900 kW x 2 Karimata No. 1 and 2 Wind Power 900 kW x 2

Validation Study Facilities

Simulation transformer

6.6kW power system

Consumer Block A Consumer Consumer Consumer Consumer Control System Consumer Control System Block B Block C Block D

PV: Solar Power Generating Facility NaS: Sodium-Sulfur(NaS) Battery Load Load LiB: Lithium Ion Battery SVR: Step Voltage Regulator SVC: Reactive Power Compensator(Static Var Compensator)

The sodium-sulfur batteries charge and discharge in order to eliminate variations in solar power generation output, and to ease fluctuations in frequency

Regardless of variations in solar power Solar power generation + Sodium- sulfur battery Frequency generation output, Solar power generation + Sodium-sulfur battery Solar power generation + Sodium-sulfur (Previous day’s plans and actual day’s results) (after solar power smoothing) battery output provide controls based on the Solar power previous day’s plans generation

Solar power generation

Sodium-sulfur Sodium-sulfur battery Variations in solar power generation output battery causing fluctuations in frequency

[No sodium-sulfur battery control] [With sodium-sulfur battery control]

Validation of the Suppression Effect for Variations in Solar Validation of the Scheduled Operation of Solar Power Power Output Generation Facilities

Frequency The sodium-sulfur batteries charge and discharge in order to eliminate variations in solar power generation output, and to ease fluctuations in frequency

Solar power generation

Wind power generation

Sodium-sulfur battery [No sodium-sulfur battery control]

Variations in solar and wind power generation output causing fluctuations in frequency [With sodium-sulfur battery control]

It is difficult to introduce wind turbines to the islands.

★Typhoons that are more powerful than before ★Incompatibility with system capacity. ★Variations in wind power generation cannot be adjusted in the power systems. Yonaguni No.1 (Damaged in Typhoon No. 15 in 2007) (Need for stabilizing equipment) ★High repair costs such as temporary construction of cranes. ★The time required to deal with defects, breakdowns, etc. reduces capacity utilization, resulting in high costs.

Initiatives for [Characteristics of tiltable wind-power generators] tiltable wind-power generator  The wind turbine itself can fall forward by an angle of close Manufacturer/country Vergnet / France to 90 degrees, enabling it to handle strong winds such as Rated output 245 kW typhoons. Rated wind speed 13 m/s  There is no need to use large cranes when building the Start/stop wind speed 4 m/s / 20 m/s No. of blades 2 blades (downwind type) structure, making it relatively easier to set up on hilly terrain. Diameter of blades 32 m  By making the wind turbine fall forward during Hub height 38 m maintenance, it is possible to carry out work on the ground level.

Blades

Nacelle

Tower (Truss-type)

Branch wires

Hydraulic winch

Standing derrick (Auxiliary tower)

 Hydroelectricity facility and cross-flow waterwheel Small hydroelectric generation Power generator Location: Miyako No.2 Power Station Guiding vane Effective head: Approx. 10 m Output: 65 kW Water wheel runner Waterwheel: Horizontal cross-flow water turbine

Waterwheel

Small hydroelectric generator facility Cross-flow water wheel

Ocean Thermal Energy Unit A Unit B Continuous Power Testing Engineering Testing Conversion (50 kW maximum output ) (Equivalent to 50kW output) Location: Kume Island Turbine generator (Top of unit A) Output: 50 kW Integrated uniaxial Condensers radial flow turbine Titanium All welded with heat transfer enhancement processing plate

Evaporators Titanium All welded with heat Source: Website of Okinawa Prefectural Deep transfer enhancement Sea Water Research Center processing plate Copyright © The Okinawa Electric Power Company, Incorporated. 9 Thank you for your kind attention.