*5.2. Selection of Renewable Energy Type for Development*

Focusing on developing the most suitable type of renewable energy would be an important first step towards better utilisation of renewable energy. Here, we will have a look at each type of renewable energy and use a comparative analysis to decide the most suitable renewable energy to focus on developing in Indonesia, considering the limitation and opportunity that each type of renewable energy has to offer, according to the expertise' inputs during the FGD.

Ocean energy is the least developed renewable energy in Indonesia. Despite having a huge potential for developing ocean energy, no commercial-scale ocean power plants now exist as it is now still under the research and development stage. According to 2019–2028 Electricity Supply Business Plan issued by PLN, there has been no technology manufacturer for ocean energy that has proven its reliability to operate commercially for at least 5 years. The development will be reconsidered once the technology is mature enough to generate electricity on a commercial scale.

Wind and solar energy can provide not only alternative sources for renewable energy but they can also give us a number of environmental benefits, as they produce a negligible amount of carbon footprints. However, the development of these renewable energy sources has major drawbacks. The initial deployment process of wind or solar energy can be quite costly, and it hinders the investment due to its exorbitant costs. Even though both solar and wind energy should be seen as low-risk investments with potentially major returns, they are hefty investments nonetheless. Moreover, both wind and solar energy are intermittent by nature, as they are heavily dependent on the weather. Therefore, the electricity generated by these renewables is most likely to be fluctuating, and it can potentially become a problem. Fluctuating supply of electricity is not a reliable power supply, as it is not best-suited for providing base-load. Furthermore, fluctuating electricity, particularly in the solar panel system, may have measurable effects on the power instrument. Therefore, relying solely only on solar and wind energy may not be the best option for now, especially for a massive commercial scale, but they may be suitable for smaller-scale development.

Biomass energy development is currently in a better state than previous sources of renewable energy now that the Minister of Energy and Mineral Resources Regulation (*Permen ESDM*) Number 50 of 2017 has been issued. Not only does it contribute to meeting the energy demands, but proper biomass energy development also allows us to cope with better waste management. However, the expensive upfront cost to get the power plants up and running has been the most common issue in developing the renewables, which also applies to biomass energy. In addition to the exorbitant upfront cost, biomass development would require additional costs associated with the extraction, transport, and storage of biomass prior to the generation of electricity. Biomass energy plants also require quite a bit of space with constant supply for biomass resources, which might not be suitable for big cities. Therefore, the development of biomass energy may be more suitable for underdeveloped, isolated region in the country.

Hydropower is by far the most established and the most utilised renewable source of energy. Hydropower has been operating as a commercial-viable, massive scale. Due to its operational flexibility, hydropower can adapt to sudden fluctuating demand, and it can be tailored to satisfy market demand, thus making it a very reliable source of energy. Its development has been very steadily growing every year, with numerous ongoing projects. However, being heavily dependent on the geographical features (i.e., large rivers) to generate electricity has been a major drawback of hydropower development. Largescale utilisation of hydropower is only limited to certain places with specific geographical features. Therefore, focusing more on a different type of renewable with huge potential for growth and suitability that needs further development might be the best option and more necessary in order to meet the 2025 national energy mix target.

Indonesia's abundant geothermal potential is not questionable. Despite having a considerable amount of potential, its utilisation, especially for the electricity generation, is not quite optimal. By 2020, only 2130.6 MW out of 28,617 MW had been properly utilised. Unlike wind and solar energy, geothermal energy is not an intermittent source of energy, and it has very high-capacity factors; thus, it can be a reliable source of energy.

Geothermal energy utilisation has very unique attributes, which can be viewed as a promising opportunity when it comes to massive development. In contrast to other renewable energy projects, geothermal power projects must include upstream activities to verify the resource and to determine the most favourable location for development. This upstream phase is very similar to the upstream process of an oil and gas field or that of a coal mine. Such a unique attribute may allow us to have a transferability of management know-how from the fossil fuel sector to the geothermal energy business. The knowledge transfer may be able to help us to reduce the hefty risk that can come during geothermal development, for instance, with the lesson from the oil and gas sector, the declining phase of production might be recognised earlier, giving us the time to work on the operational and managerial solution to avoid the pitfall. The nature of the geothermal operation and the availability of knowledge transfer can reflect on the managerial maturity that the geothermal sector can offer, compared to the rest of the renewable energy sources, thus becoming its greatest opportunity. It is also implied that geothermal energy, far from being a simple market competitor, is internalised within the oil and gas industry as the inevitable way forward, hence the emphasis on transferability of knowledge.

The geothermal energy sector has a fair share of obstacles when it comes to its development. Similar to the other renewables, the hefty cost has been one of the biggest obstacles that Indonesia has faced in the development of geothermal energy. The exploration and resource commercialisations are both costly processes, which makes it very reliance on heavy investments. Regulations have also become one of the major challenges for the geothermal sector, for instance, the land dispute caused by wavering regulations are most likely to hinder its development. There might have been many more underlying issues with regard to geothermal energy development; therefore, a further investigation on the geothermal supply chain trajectory is necessary to address the potential barriers in its development. Furthermore, developing a set of policies also can be done to bridge these potential barriers and to ultimately enhance the pace and magnitude of geothermal energy development [49]. Despite the obstacles, just as much as the other types of renewable energy, the high potential, reliability, and opportunity that geothermal energy can offer make it the most suitable renewable energy source to develop.
