Lesser Sunda Island: The House of Indonesian Tidal Current Power

(FI | 25/03/2025)

Figure 1. Illustration of bottom-fixed underwater turbine (source: The University of Edinburgh)

The global campaign to reduce fossil fueled-based power production escalates the urge for energy transition to renewable energy. Particularly for a maritime continent such as Indonesia, the potential of ocean-based renewable energy is something interesting to discuss. The most popular technology – the tidal current energy conversion – is one of the outstanding topics that has been studied frequently in Indonesia.

Basically, this technology converts tidal-generated ocean currents into electricity power through the deployment of underwater turbines. There is a range of cut-in current speed to initiate the movement of turbine, usually ranging from 0.5 to 1.0 m/s, depending on how big propeller is installed. The most common site to discover ocean currents in and over that such range are straits, which also has potential to maintain the turbine operational window throughout the year. More than fifty straits are distributed over Indonesia Maritim Continent; however, the Lesser Sunda Island possesses the most interesting tidal current potential. The Lesser Sunda Islands, also known as Nusa Tenggara, are a group of islands in the southeastern part of the Indonesian archipelago. They are located to the east of Java and Bali and stretch eastward toward Timor.

Prior to the discussion of tidal current potential in Lesser Sunda Island, we encourage the readers to understand the urgency of Indonesia’s energy transition in relation to the global and regional renewable energy.

The urge of renewable energy in Indonesia

The Paris Agreement (2016) calls for countries to speed up the energy transition from fossil fuel to renewable energy. The agreement also encourages countries to cooperate to achieve more ambitious goals in energy transition. The urge comes from the Paris Agreement’s long-term goal, which is to keep the rise in global surface temperature to well below 2°C above pre-industrial levels. The agreement also states that preferably the limit of the increase should only be 1.5°C

In response, the ASEAN country gathered and agreed to several targets regarding renewable energy development in Southeast Asia. ASEAN countries are in one-tone to increase the contribution of renewable energy to 23% in the total primary energy supply. The countries also agree to reach 30% energy intensity reduction. On the grass-root level, countries encouraged to reduce the average fuel consumption per 100 km of new light-duty vehicles sold in ASEAN by 26%.

Figure 2. Indonesia’s electricity consumption for period 2015-2022 according to BPS

Indonesia, which is home for slightly over 281 million people, increased the energy consumption every year. The average growth rate of total energy consumption is 12 TWh for the period between 2015 and 2022. Additionally, every person consumes on average 1.20 MWh of power every day in 2022. By 2045, Indonesia expected to gain a demographical bonus with the estimated population will grow up to 324 million. Thus, a huge increase in power consumption will occur along with the increase in population.

What makes Lesser Sunda Island interesting?

Straits of Bali, Badung, Lombok, Alas, Larantuka, and Boling spread along the Lesser Sunda A, which possesses great tidal-based renewable energy potential. Currents are generated from the combination of tidal dynamics which follow the lunar pattern and density gradients which move throughout the year following the climate dynamics. The density gradient current is part of the global thermohaline circulation moving through Indonesia’s internal sea, commonly known as the Arus Lintas Indonesia (ARLINDO) or Indonesia Throughflow (ITF). This current penetrates through the gap on the northern part of Indonesia which directly connected to Pacific Ocean, then moving towards south into Indian Ocean through the narrow straits and passages along Lesser Sunda Island. The combination of tide and density gradient current, and the straits morphology that are relatively narrow with deep bathymetry, lead to strong currents that move along the year and are suitable for underwater turbine placement to generate electricity power.

Figure 3. BW’s hydrodynamic model to estimate tidal current power in Alas Strait, NTB

There are three straits with outstanding potential, Lombok, Alas, and Larantuka. Research conducted by Orhan, et al. (2016 and 2017) found that those straits possess up to 3.4 or 19.4 TWh potential extractable power cumulatively. Such amount should be able to cover the domestic electricity (non-commercial) needs for Bali, NTB, and NTT provinces, while also reducing our dependency on fossil fuel-based electricity power. In 2024, Statistic Center Agency (BPS) shows that the three provinces need at least 10.3 TWh power every year, with the grow rate up to 0.56 TWh year-by-year since 2014. Though there are several alternatives for renewable energy in this area (e.g. offshore/onshore wind turbines, solar energy, etc.) Tidal current-based energy are highly recommended due to its high output predictability, continuous energy generation, minimum land-use, and minimum noise/visual pollution.

As a company specializing in hydrodynamics, meteorology, and climate, is committed to supporting Indonesia in enhancing renewable energy production and reducing dependence on fossil fuels. We strive to provide accurate and reliable renewable power generation estimates to help drive the country’s transition to sustainable energy. Interested in discussing the implementation of this technology? Contact us at bw@bwgeohydromatics.com or connect with us on LinkedIn.

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