Investigation of availability, demand, targets, and development of renewable energy in 2017–2050: a case study in Indonesia

Abundant potential of renewable energy (RE) in Indonesia is predicted to replace conventional energy which continues to experience depletion year by year. However, until now, the use of RE has only reached 2% of the existing potential of 441.7 GW. The main overview of this work is to investigate the availability of RE that can be utilized for electricity generation in Indonesia. National energy demand and targets in the long run during the 2017–2050 period are also discussed. Besides, government policies in supporting RE development are considered in this work. The results show that the potential of RE in Indonesia can be utilized and might replace conventional energy for decades. The use of RE for electricity generation can be achieved by employing a government policy that supports the investor as the executor of RE development. The selling price of electricity generated from RE is cheaper than electricity generated from fossils; this makes economy is more affordable for people. Finally, the target set by the government for utilizing RE as the main energy in Indonesia can be done by implementing several policies for the RE development. Thus, greenhouse gas emissions and the use of petroleum fuels can be reduced.


Introduction
Indonesia is one of the Southeast Asia countries and even in the world that has problems with the energy crisis. The number of Indonesia's oil imports during the 2009-2019 period reached 49.1 million tons, with an average import of 3.6%/year (BPS 2019a). Based on the energy mix (EM), sustainable development (SD) and low carbon (LC) scenario show that Indonesia's energy demand in 2025 will be 170.8, 154.7 and 150.1 MTOE, respectively. Meanwhile, in 2050, Indonesia's overall energy demand will reach 548.8, 481.1 and 424.2 MTOE (ESDM 2019). Total primary energy production consisting of petroleum, natural gas, coal, and other REs in 2018 reached 411.6 MTOE. From the total production, 64% or 261.4 MTOE were exported mainly for coal and LNG. Final energy consumption in 2018 (without biomass) reached 114 MTOE consisting of transportation sector of 40%, industry of 36%, household of 16%, commercial of 6%, and other sectors of 2%.
Energy is one of the main factors in the context of sustainable development to eradicate poverty, protect the environment, increase prosperity, and speed development (Santika et al. 2020). The abundant availability of RE in Indonesia has been widely expressed by several researchers and has been widely discussed earlier. Indonesia has the highest availability of coal energy at 51% in Southeast Asia (Erdiwansyah et al. 2019a). Meanwhile, Indonesia's oil production level is the second highest after Brunei Darussalam. Indonesia's oil production is 12.02% while Brunei Darussalam's natural gas production is 18.06% (Erdiwansyah et al. 2019). Indonesia has targeted the use of RE in 2025 is 23% with a feed-in tariff policy system. RE is very possible to be used as the main energy to replace petroleum (fossil) which continues to experience depletion every year. Discussions on Indonesia's RE policy and prospects have been conveyed (Maulidia et al. 2019). The application of RE in various ways can also reduce carbon emissions which has been providing high enough air pollution, especially from vehicles and industry (Deendarlianto et al. 2020). Determination of the RE target of 23% is in line with the determination of the use of oil consumption by 25% nationally. The selection of a sustainable solar system (solar), a sustainable biogas system (biogas), an efficient lighting device (Lighting), an efficient cooling device (Cooling), and an efficient cooking stove (Cooking) scenario aims to reduce emissions levels sustainably. In this case, this action is estimated to be able to save cooling energy by 22.99% in 2050 (Kusumadewi and Limmeechokchai 2017;Erdiwansyah et al. 2019b;O'Ryan et al. 2020;Ben Jebli et al. 2020;Khanna et al. 2019). One of the RE developments that has attracted foreign investors in solar PV is reported by (Kennedy 2018). The installed solar PV capacity increased from 9 megawatts (MW) to more than 240 MW in 2017. However, foreign investors often face problem such as lack of government policy towards RE developers. Therefore, many interventions are not expected in the field. Targets for achieving efficient use of RE systems have been prioritized in the decarbonization of Indonesia's electricity systems (Indra Al Irsyad et al. 2020).
The application of RE has also greatly impacted the economic improvement and reduced carbon dioxide emissions. In addition, adverse effects on climate change and global warming can be reduced by applying RE permanently (Gozgor et al. 2020). Investigations on the effects of economic policy uncertainty differentiation on various types of energy company investments using the panel regression model have been reported (Liu et al. 2020). Economic growth with RE consumption can drive for longterm financial development (Eren et al. 2019). Investigations into the short-term and long-term economic growths of RE use have also been discussed recently (Alam and Murad 2020), in which the results show that the use of RE can significantly increase economic growth and improve welfare. The global energy transition system is one of the trends to provide promising economic opportunities in the future (Jenniches 2018). The use of RE can save money commonly used for energy needs. This is because RE is cheaper than fossil fuels. The impact of RE and financial development on carbon dioxide (CO 2 ) emissions and the economy has been reported (Charfeddine and Kahia 2019), in which the results show that RE consumption and financial development influence CO 2 emissions and economic growth. The effect of economic growth on the consumption of renewable and non-RE used to inspect Asia-Pacific Economic Cooperation (APEC) countries (Zafar et al. 2019). The consumption of renewable and non-RE used to achieve the target in reducing emissions globally has been implemented since 1997-2014 (Alola et al. 2019). While in Indonesia, emissions reductions have also been carried out such as the development of RE by implementing several policies for developers. Policies that support RE developers must be made and implemented by the stakeholders. Besides, the government must also target more efficient use of energy in the future. The government's step in targeting the use of RE in the future is very appropriate. Besides, the government can save more budgets and can further improve the welfare of the community.
The energy found in Indonesia is very abundant, especially those from renewable energy (RE) sources though they have not been used optimally. This is because the available resources are inadequate to support the development of RE. The study became important due to its discussion on the availability, demand, targets, economic growth, and development of RE might improve the quality of government planning in energy, especially for RE development planning. Issues in this article can enhance the future government planning for about 30 years (up to 2050).

Material and method
The process of analysis is a very important thing to do in a study. There are two rare methods used in the study, namely analysis and categorization. The analysis process is based on the arguments contained in the categorized literature. The arguments reviewed in the study are explained in detail in Sect. 3, while the fifth section presents overall conclusion. The literature analyzed in this review was obtained from various databases including Science Direct, Web of Science, IEEE, and various research results both from government institutions and from universities. The database generally produces various fields of science such as the development of RE that has high quality.

Analysis data
The literature review analyzed in this research is based on RE sources that cannot be utilized optimally as shown in Fig. 1. Where the total potential of RE found in Indonesia reaches 441.7 GW with an installed capacity of 9.07 GW. Meanwhile, the new energy can be utilized to date has only reached 2%. The analysis and review in this paper discuss the availability, demand, targets, economic growth, and development of RE in Indonesia in the period of 2017-2050. Renewable energy discussed includes geothermal, hydropower, bioenergy, wind power, solar power, and tidal/wave. Once the analysis of RE availability is done, energy targets and demand in the next few years are then discussed. Then, energy supply, economic growth, RE policies, risks, and RE challenges are described sequentially and finally concluded.

Categorization
There are 3 types of references used in the study, namely literature taken from academics, reports from industry, and documents about various policies. The last two types of references were collected online by the author or through research submitted. Collection of academic literature was obtained from databases such as Science Direct, Web of Science, and IEEE using the keywords of potential RE. In this stage, identification was carried out aiming to produce   (Purwanto et al. 2016;ESDM 2019;Nugroho 2019). The decline in oil production was caused by several factors such as production wells that were no longer feasible. While the development of new wells for production was still very limited. However, until now, Indonesia has a dependency on petroleum. The available petroleum cannot meet the needs of the existing refineries, so the government of Indonesian continues to import from other countries such as the In general, energy demand in 2018 reached 465.07 million barrels/year including biodiesel fuel. Total domestic oil production is 278.01 barrels, while the total amount of oil imported by the government of Indonesian from oil-producing countries is 165.04 barrels/year. The comparison of total oil production and import each year can be seen in Fig. 2b. In 2017, Indonesia was ranked the third-largest country in terms of crude oil imports after Singapore and Thailand at US$21.04 and US$ 20.1 billion, respectively. The total of Indonesia's oil imports was US$8.1, Malaysia was US$3.9, the Philippines was US$3.5, Brunei Darussalam was US$1.6, and Vietnam of US$93.2 million (CNBC 2017).
Natural gas consumption in Indonesia in 2018 was 1.7 million MMSCF for the industrial sector of feedstock/ energy, electricity generation, city gas (household and commercial), and gas lift (ESDM 2019). In addition, this natural gas is also an export commodity with an annual average of 1.2 million MMSCF in the form of LNG and gas. LPG consumption in 2018 was 7.5 million/tons, supplied from import of 74% (5.5 million/tons) and domestic production of 26% (2 million/tons). In 2018, the total percentage of LNG exports to natural gas decreased to 40% compared to 2009 by 50% as shown in Fig.3.
Conversion of kerosene to LPG by the government has increased the LPG consumption in the community. Meanwhile, the availability of LPG produced domestically is still very limited. Consumption of 3 kg LPG continues to increase due to subsidies from the government. Therefore, the government must anticipate this increase since in the implementation, it is considered mistarget.

Potential and Implementation RE in Indonesia
The availability of RE which is quite a lot can replace the dependence of fossil energy. This can be done if the existing RE can be utilized optimally. Thus, the global government's commitment to reduce greenhouse gas emissions can be achieved. As a result, it has encouraged the Government to increase the role of RE sustainably as part of maintaining domestic energy security and independence. Following the Government Regulation No. 79 of 2014 on the National Energy Policy, the target of RE in 2025 is at least 23% and 31% in 2050. Indonesia has very abundant potential of RE to achieve the primary energy mix target.
The total RE potential in Indonesia reached 441.7 GW in 2019 with an installed power of 9.07 GW or only 2% of the total that can be utilized. Total RE of 441.7 GW is sourced from tidal/wave energy potential of 17.9 GW, geothermal of (potential resources 11.0 GW, reserve 17.7 GW and realization of PLTP 1.808 GW), bioenergy of (potential 32.6 GW, BBN 200 Bph and Realization of PLTBio 1.840 GW), wind power potential of 60.6 GW and realization of PLTB 1.1 MW, and solar power potential of 207.08 GW and realization of PLTS 0.090 GWp show in  One of the RE sources in Indonesia that cannot be utilized properly is solar energy. The potential of solar energy can be found almost in all provinces in Indonesia. However, the utilization of this energy has not been optimal, even though solar energy can be used as electrical energy, heating, cooling, etc. The highest potential of solar energy is found in the province of West Kalimantan of 20,113 MW. Furthermore, the potentials of solar energy can be found the provinces of South Sumatra, East Kalimantan, and North Sumatera, respectively, 17,233 MW, 13,479 MW, and 11,51 MW. Meanwhile, the least solar energy potentials are found in Jakarta and Bangka Belitung, respectively, 225 MW and 281 MW as shown in Fig. 5. The total utilization of solar energy in Indonesia in 2018 was 0.05% of the total potential. However, the government's target for the solar energy utilization in 2025 is 1.047 MWp compared to 9442 MWp in 2018 (ESDM 2018).
The total potential of RE in Indonesia such as geothermal, solar, bioenergy, wind, hydro, mini-micro hydro, and tidal/wave reaches 239,970 MW. Meanwhile, the RE installed capacity in 2019 is only 8215.5 MW. The total of new RE that can be utilized until 2019 reached 17.452%. It is assumed to be very small compared to the existing potential as shown in Table 1.
The total target of RE development during the period 2019-2028 shows that the use of RE is more dominant. This is because conventional energy reserves (fossil) are running low so the government has to import substantial oil. With the development of RE, the government can reduce oil imports that have continued to soar in recent decades. Development for hydropower energy power plants is the highest compared to other energy. Meanwhile PLTP, PLT Bio-Fuel, PLTMH and PLTS were ranked Meanwhile, in the sixth, seventh and eighth place, respectively PLT Bayu, PLT Biomass and PLT Wave. RE development in Indonesia is generally spread in five islands including Sumatra, Kalimantan, Java-Bali, Sulawesi, and Maluku and Papua as shown in Table 2. The highest total capacity target for RE is in Sumatra Island with a total capacity of 8852 MW. While the highest potential for RE that has not been utilized during the 2017-2026 period is found in Sulawesi Island at 4155 MW. The type of RE for the highest installed capacity is hydropower energy of 12,342 MW. While the potential of hydropower energy that has not been utilized is 6869 MW. The total installed capacity of hydropower energy in Java-Bali is higher than Sumatra Island and other islands. However, the potential of hydropower energy during the period 2017-2026 does not exist. Meanwhile, the highest potential of hydropower energy that has not been utilized is in Sulawesi Island of 3852 MW. The total installed capacity of RE in Indonesia until 2026 reaches 21.549 MW and the potential for RE that has not been utilized in the same period is 9.3889 MW (Caraka 2016;Widyaningsih 2017;RUPTL 2019).
Overall, energy sourced from biomass found in 27 provinces in Indonesia is 23,335.07 MW. The most biomass energy sources are in Riau province of 4,169.6 MW and followed by the provinces of North Sumatra and South  Sulawesi of 2,796.01 MW and 2,061.04 MW, respectively. Meanwhile, the smallest biomass energy source is in Jakarta of 0.5 MW as shown in Fig. 7a. The small potential of biomass in Jakarta is caused by the area of mapping and has been met by housing residents. Whereas for forest areas, it is almost certain that there are no more in Jakarta. Meanwhile, if compared to the forest area in Riau and Sumatra Utara provinces, it is far more than Jakarta. Furthermore, the potential source of biogas energy in Indonesia is also very adequate when used for energy, especially for electricity generation. The first most potential sources of biogas energy are in Jakarta, Banten, and North Sumatera with 126.01 MW, 118.06 MW and 115.05 MW, respectively, as shown in Fig. 7b (Mulyana 2016; Wulandari et al. 2020). The potential for biogas energy in Indonesia in 2016 reached 2,603 MW. The potential of biogas is much smaller than the potential of biomass reaching 30,051 MW. However, it is predicted that the potential of biogas will continue to increase along with the increase in other RE sources, mainly from agricultural products. The high biogas in these three provinces can be due to the high number of the population so that the potential for biogas produced is more than the other provinces. Utilization of solar energy as electricity generation aims to increase national energy security, reduce dependence on the use of fossil fuels, and increase economic investment. In addition, it can make domestic industries are more efficient, reduce greenhouse gas emissions, and meet the government's target of RE use by 23% by 2025. The Government of Indonesia has set targets for the use of installed solar energy in 2025 by 1,008.4 MW (Sugiyono 2016;ESDM 2019). The use of the energy mix in 2025 is targeted by the government for coal of 54.6%, natural gas/ LNG of 22%, RE of 23% and fossil energy of 0.4%. The target for energy use in 2025 is adjusted to government  policies in utilizing RE and gas, so that dependence on fossil energy can be reduced. The development of RE can be increased until 2028 by seeking to be able to increase the capacity of PV roofs of 3.200 MW for 1.6 million customers. Electricity energy production in 2028 is targeted at 500.691 GWh, mostly produced from coal energy of 272,354 GWh, gas of 110.150 GWh, hydro of 54.736 GWh, Geothermal of 48,217 GWh, RE and fossil energy of 13,205 GWh and 2,019 GWh, respectively, as shown in Fig.8a. Based on the composition of electricity production by type of fuel, the government's target to reduce the use of fossil fuels and reduce imports can be achieved. However, to achieve this target, a strong government policy and adequate resources are needed. Meanwhile, Fig. 8b shows the composition of the energy mix for electricity generation. Based on the composition of the power plant using the energy mix, the government's target to reduce greenhouse gas emissions in 2028 can be achieved. Therefore, air pollution caused by industrial fuels and vehicles can be realized. The composition of production and generation with a mixture of energy during the period 2019-2028 is shown in Fig. 8a, b. To be able to support this energy production target, sufficient fuel is needed with adequate availability. If the availability of this fuel is lacking, it is highly unlikely that targets for energy production and emission reductions can be achieved.

Target RE
The government's RE targets in 2025 and 2050 are 23% and 31%, respectively, as shown in Fig. 9a, b. It can be seen that the RE target becomes greater than the other energy mix. Meanwhile, the petroleum energy mix will decrease to 20% by 2050. The increasing population has driven the increasing demand for energy, especially for transportation and electricity. Meanwhile, fossil energy production (non-renewable) will continue to decline, forcing the government to import petroleum to meet domestic needs. To overcome fossil fuels that continue to experience depletion, the government has made several policies to support the use of RE nationally. The government's target is to meet national energy by building several electricity generators such as geothermal energy, solar energy, and bioenergy, hydropower, and wind power. Besides, the government made policy on the use of biofuels (B20), namely mixing diesel engine fuel with palm oil to  Meanwhile, the final energy demand from the LC scenario to EM can save 23% by 2050 as shown in Fig. 10. The total amount of energy demand in 2050 is predicted to be still dominated by the transportation and industrial sector. This is due to industrial growth and the increase in the volume of motor vehicles accompanied by an increase in population which increases every year. Final energy demand by type of energy in 2050 shows that electricity demand will dominate by 35% (EM), 34% (SD) and 33% (LC), respectively (Sugiyono 2016;ESDM 2019). The high demand for electricity can be influenced by the increasing use of electronic devices, especially in the household sector. In addition, the substitution of the use of generators in the industrial and commercial sectors with fuel oil to using electricity on the grid. Energy demand for the industrial sector in 2050 is estimated to reach 230.9 MTOE sourced from EM, SD of 194.03 MTOE and LC of 157.07 MTOE. The use of energy in this industry is divided into six parts including the cement industry, fertilizer, paper, ceramics, metals, and the food/beverage industry. The total amount of energy demand in the industrial sector reaches 87%. For the transportation sector, energy demand is still dominated by fuels such as diesel, gasoline, biodiesel, bioethanol, gas, avgas, and aviation fuel. The transportation sector consumed 96% of fuel in 2018 and the rest was supplied by natural gas and biodiesel. The biggest energy demand for transportation in 2018 was dominated by motorcycles, i.e. 41%. Energy demand for air transportation in 2018 also increased and in 2050 demand for aviation fuel is predicted to reach 27.06 MTOE. Energy demand for the trucking sector in 2050 is projected at 43%. For passenger car transportation, although there is an upward trend in energy demand, its growth has been able to be tempered by the use of more efficient technology. Therefore, energy demand in 2050 is projected to increase from 6.07 MTOE in 2018 to 23.07 MTOE in the EM scenario and 21.01 MTOE in the SD scenario and 20.9 MTOE in the LC scenario.
Energy demand in the household sector is affected by the increasing number of households predicted to reach 70.6 million in 2025 and around 80 million in 2050. In addition, the level of urbanization drives future energy demand increases. Based on BPS projections, in 2035, the   Fig. 11a. Meanwhile, energy demand for transportation in the EM scenario and the sustainable development scenario (SD) shows the share of conventional oil demand until 2050 is still high. However, in the low carbon (LC) scenario, the share of conventional (fossil) oil demand in 2050 is estimated to decrease due to the application of mixing biodiesel by 100% (green diesel) and bioethanol by 85%. Thus, the share of oil demand in the LC scenario in 2050 becomes 37% and the RE demand share increases to 62% as shown in Fig. 11b. Energy demand for the household sector in 2050 is estimated to reach 323.7 MTOE sourced from 120 MTOE (EM), 109 MTOE (SD), and 94.7 MTOE (LC). The share of electricity demand is estimated to increase from 60% in 2018 to 90% in 2050. The increasing electricity demand is driven by the increasing use of electronic equipment such as air conditioners, refrigerators, water pumping machines, and induction electric stoves. Meanwhile, the demand for LPG in the EM, SD, and LC scenarios in 2050 reached 4.8 MTOE, 4.3 MTOE and 3.4 MTOE as shown in Fig. 12a. In the commercial sector such as offices, hotels, restaurants, hospitals and other services, the demand for energy is dominated by electricity, LPG, diesel, gas, biodiesel, and DME, reaching 60%-70%. Electricity consumption is used for air conditioning (AC), water pumping machines, and lighting (lamps). Total final energy demand for the commercial sector in 2050 is estimated to reach 124.4 MTOE sourced from 47.7 MTOE (EM), 40.5 MTOE (SD), and 36.2 MTOE (LC) as shown in Fig. 12b.

Energy supply
In 2050, the primary energy supply is targeted to reach 943 MTOE compared to 2025 at 314 MTOE. The supply of primary energy for power plants is included in the modelling based on the assumption of generating capacity according to the electricity supply business plan (ESBP) which generates the primary energy requirements for each power plant (RUEN 2017;Widyaningsih 2017;ESDM 2019;Mahidin et al. 2020). In this case, 298 MTOE (32%) is sourced from coal energy. It is expected that the use of coal can increase added value to the process of coal gasification and coal liquefaction. Energy demand sourced from gas pipelines, LNG, and LPG in 2050 is predicted to be 222 MTOE (24%) of the total primary energy supply. Meanwhile, the supply of RE is around 29% (275 MTOE) in 2050. The increase in the supply of RE is influenced by the optimization for the utilization of solar cell energy, geothermal energy, biomass, and water that is intended for electricity generation and fuel subsidies in the transportation sector. In the SD scenario, the primary energy supply is smaller than the energy mix (EM) scenario of 828 MTOE in 2050. However, in the SD scenario, the RE energy is greater than the EM scenario, which is 23% in 2025 and 32% in 2050. This figure is following the targets listed in the KEN and RUEN. In the special LC scenario, RE increases significantly by 58% in 2050 compared to 2025 by 36%. The comparison of the primary energy mix with SD and LC 2025-2050 scenarios is shown in Fig.13a, b.

Economic growth
Indonesia's economic growth in 2017 and 2018 were 5.07% and 5.17%, respectively, as reported in the data from the Central Statistics Agency (CSA) (BPS 2019b). In 2019, it increased to 5.3% and in 2045 it is targeted at 5.6%. ESBP stated that Indonesia's economic growth uses BAPPENAS scenario in 2028 of 6.45% (RUPTL 2019). This is one of the factors to consider in making scenarios of long-term domestic energy demand. Economic growth statistics are accompanied by energy demand in general. Energy demand is closely related to economic activity, so the assumption of economic growth will be very sensitive to energy demand from the three scenarios developed as shown in Table 3. Indonesia's economic growth during the 2013-2018 period tended to decrease from 5.6%-5.17% as a result of the global economic downturn due to financial market uncertainty and declining trade volume at the world level. The assumption of economic growth is adjusted to the ''Vision of Indonesia 2045'' published by BAPPENAS (Nasional and Nasional 2017;Garuda 2018). The Indonesia's economic growth in the next few years is supported by rising domestic needs, including consumption and investment, as well as better export growth including in the manufacturing sector which is a major energy consumer in the industrial sector. KEN mandates for RE mix target in the primary energy mix of at least 23% by 2025 and minimizes the use of petroleum less than 25% by 2025. In addition, energy efficiency is also targeted to decrease by 1% per year to encourage savings in energy use in all sector. Some targets in the KEN which are also considered in the projected energy demand include optimization of the use of natural gas for domestic use and priority use of fossil energy for national industrial raw materials. This policy is implemented to maximize the use of RE, minimize the use of petroleum, optimize the use of natural gas and RE, use coal as a mainstay of national energy supply, and use nuclear as a last resort. With the regulations set by the government, it is expected that the developers (investors) can work better and the targets set can be achieved.

Risks and challenges RE
In the construction of RE project, investors sometimes need to evaluate the risks that may arise when construction or operations begin. Each RE project has different types of risks and obstacles (Goh et al. 2014). A study conducted by the United Nations Environment Program (UNEP) elaborates some of the risks that are generally inherent in the development of RE projects as shown in Table 4 (Gray 1990;Holdren et al. 2000).

The electricity selling price
The price of electricity sales to customers from RE is cheaper compared to conventional energy as shown in Table 5. Meanwhile, the cost of conventional energy production is cheaper than RE, except for the production of wind power plants. However, RE has more advantages than conventional energy. The benefits of include environment friendly, more lace emission, reusable, sustainable, and lower operational costs. Meanwhile, conventional energy has higher operational costs compared to RE despite lower production costs. In addition, conventional energy produces higher emissions than RE.

Conclusions
Investigation of the potential for RE regarding the amount of utilization, energy demand, and the target of power plant construction during the period of 2017-2050 has been completed. Various findings have been presented and discussed earlier so that conclusions can be drawn as follows: ( (3) By using RE, economic growth is targeted to increase to 5.6% in 2045 compared to 2019 of 5.3%. (4) The policy set by the government in supporting the development of RE to achieve the target of energy use by 23% in 2025 and to reduce the use of petroleum by 25% in 2050. (5) Time of permit issuance, construction price, resource price, intimidation, etc. is a risk commonly faced by investors in the development of RE.
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