The Kingdom of Tonga Tonga Power Limited PREPARATORY SURVEY REPORT ON THE PROJECT FOR INSTALLATION OF WIND POWER GENERATION SYSTEM April 2017 Japan International Cooperation Agency (JICA) Kokusai Kogyo Co., Ltd. Toyo Sekkei Co., Ltd. IL JR 17-035 Summary Summary 1. Outline of the Recipient Country The Kingdom of Tonga (hereinafter referred to as “Tonga”) is located in the South Pacific and consists of 176 islands. The largest island is Tongatapu Island, which is the residence for 73 % of the population of Tonga. The Tonga Trench, which is the continental plate boundary, exists on the east side of Tonga from north to south. Most of the ground of Tongatapu Island is formed from raised limestone. The temperature is highest between December and March. The monthly average high temperature is about 30 degrees Celsius, and the monthly average low temperature is about 23 degrees Celsius. Generally, from January to March is high precipitation and from July to October is low precipitation. The wind speed at the airport located in the southeastern part of Tongatapu Island is about 3 to 5 m/s and stable throughout the year. In addition, in Nuutua, the project site of this Project, wind speed is also stable at 6 to 10 m/s throughout the year. The wind direction mostly consists of east-southeast winds (from the direction of the sea), so the wind conditions are favorable. However, in Tonga, cyclones commonly occur in the summer season (usually from December to April), especially from January to February. The scale of cyclones has increased in recent years, and in February 2016, a cyclone named Winston, with maximum instantaneous wind speed of 84.9 m/s, occurred. After approaching Tonga, cyclone Winston caused serious damage to Fiji. Due to the geographical conditions of being an "island country", Tonga imports of oil fuel account for about 20 % of total imports, which is equivalent to 10 % of GDP. Major industries are agriculture, fishery and tourism. However, 31 % of GDP is occupied with remittance from overseas since the economy of Tonga largely depends on grant aid assistance from other countries and money transferred from migrant workers. 2. Background and Outline of the Project (1) Overall Goal Tonga is greatly affected by global crude oil price fluctuations and is extremely vulnerable from the viewpoint of energy security. In response, the Cabinet of Tonga constituted in 2009 a policy goal of “increasing the proportion of renewable energy to 50% of the entire electricity supply by 2020” to deal with two crucial issues: greenhouse gas emissions reductions and improvement in energy security. On this basis, Tonga had installed 2.3 MW of photovoltaic systems on Tongatapu Island. To further increase the proportion of renewable energy, Tonga expects wind power generation facilities to be developed on Tongatapu Island. Therefore, this Project aims to contribute to the stable supply of energy in Tonga, by developing a wind power generation system and grid stabilization system on Tongatapu Island, promoting the utilization of renewable energy and diversifying the power supply source. (2) Current Conditions and Problems The soaring of the global crude oil prices in 2008 obliged the Tongan authority to raise electricity charges to TOP 1.00/kWh (approx. USD 0.5/kWh), causing serious impact on economic activities and the peoples’ lives in the country. Having learnt from this experience, the government of Tonga formulated a Tonga Energy Road Map 2010-2020 (hereinafter called the “TERM”) as an implementation policy to achieve the policy S-1 Summary goal: “increasing the proportion of renewable energy to 50% of the entire electricity supply by 2020”. TERM listed various types of renewable energy, but only photovoltaic and wind power generation are judged to be available renewable energy sources which have abundant potential at the present time and can be connected to the existing grid system on a large scale. In December 2015, a draft of a commitment voluntarily determined by each country (Intended Nationally Determined Contributions: INDC) was formulated in Tonga to achieve the objectives of the United Nations Framework Convention on Climate Change. In addition to TERM's policy, INDC plans to achieve both emission reduction and investment for climate recovery, such as increasing the proportion of renewable energy to 70 % by 2030 and increasing energy efficiency. Through INDC, Tonga explicitly shows it is taking cost-effective actions and avoids cost increases due to inaction in dealing with to climate change. Based on the above situation, Tonga has developed a total of 2.3 MW of photovoltaic power output; a 1.0 MW power storage system and a 1.3 MW micro grid control system with the support of New Zealand and Japan. However, in order to achieve TERM's goal of “increasing the proportion of renewable energy to 50 % of the entire electricity supply by 2020”, in addition to the development of further renewable energy, a stable supply of renewable energy and frequency control of the power system are required. To cope with this, it is imperative for Tonga to further develop renewable energy as well as to stabilize the power supply based on the existing micro grid system and suppress the frequency fluctuation of the power system as much as possible. (3) Background and Outline of the Project On Tongatapu Island, the target island of this Project, Tonga Power Limited (hereinafter referred to as “TPL”) supplies electric power by operating eight diesel generators with a total rated capacity of 14.16 MW. The power consumption varies according to the season with the maximum power consumption at about 9.1 MW. Although renewable energy has been developed, most of the power supply is still being covered by these diesel generators. Therefore, from the viewpoint of national energy security, the Tongan government considers the development of renewable energy and reduction of imported fuel consumption through promotion of energy conservation as an important policy challenge. In particular, based on TERM, TPL plans to increase the output power of photovoltaic and wind power generation systems to 9.3 MW and 6.6 MW, respectively. In Tonga, the installation of photovoltaics as renewable energy has been moving forward, and many independent photovoltaic systems are developed in isolated islands where diesel power generation is non-existent. Since the 1990’s, through the support of Australia, EU and Japan, installation of residential home solar photovoltaic systems has been progressing in each of the remote islands of Tongatapu, Vavaʻu, Ha'apai, and Niuas. Regarding the grid connection type of photovoltaic systems, a 1.3 MW photovoltaic system was developed on Tongatapu Island with the support of New Zealand, and a 500 kW photovoltaics system was developed on Vavaʻu Island by the UAE. In addition, a photovoltaic system with a maximum output of 1.0 MW, a grid stabilization system with a capacity of 1.0 MW, and a micro grid control system has been installed through Japan's grant aid. In addition to photovoltaics, a feasibility study of wind power generation was carried out under the cooperation of the government of New Zealand and the potential of wind power generation was confirmed. In this way, with the support of Japan and other donors, the introduction of S-2 Summary renewable energy is progressing, but in order to attain the targets listed in TERM by 2020, it is necessary to secure more diverse sources of electric power. Under such circumstances, in 2014, Tonga made a request for the introduction of a wind turbine generator system and grid stabilization system in Tongatapu Island, as a Japanese grant aid project. In response to this request, the government of Japan implemented the preliminary survey. In this Project, it is expected to introduce the wind turbine generator system and grid stabilization system which are suitable for the environment of Tongatapu Island, to diversify energy resources, and to contribute to the improvement of the rate of energy self-sufficiency. 3. Summary of the Survey and Contents of the Project (1) Summary of the Survey 1) Wind Speed and Cyclone In Tongatapu Island, a wind condition survey is being conducted at a height of 40 m in Niutoua, the project site, under the support of New Zealand. The wind condition data are shown below. Figure 1 Monthly average wind speed in Niutoua (2015 April – 2016 March) Wind speed is stable at 6 to 10 m/s throughout the year, and since the Niutoua area faces the ocean, coupled with the high altitude of the observation point, the wind speed conditions are favorable. Figure 2 Annual wind rose (2015 April - 2016 March) S-3 Summary The wind direction concentrates from the east-southeast to the southeast, and wind direction is constant throughout the year. Both wind speed and wind direction are very stable, and it can be confirmed that this environment is suitable for wind power generation. In Tonga, cyclones commonly occur during the summer season (usually from December to April), especially from January to February. About 60% of cyclones are category 2 (30 m/s at 1 minute average wind speed), but category 4 and 5 cyclones (more than 50 m/s at 1 minute average wind speed) also occur. The strength of cyclones has increased in recent years. In the past, category 4 and 5 cyclones had occurred about once in 10 出典：ABC News years, but five category 4 and 5 cyclones have already Figure 3 Damage situation by Winston (Fiji) occurred since 2010. In February 2016, a cyclone named Winston, with maximum instantaneous wind speed of 84.9 m/s, occurred. After approaching Tonga, cyclone Winston caused serious damage to Fiji. 2) Ground Condition New Zealand carried out the digging (depth: about 2.5 m) of the test pits at 7 places in 2014 and 17 places in 2015.