Scenario of renewable energy transition from fossil energy resources towards net zero emission in Indonesia

. In 2011, Indonesia set a 26% reduction goal for greenhouse gas emissions by 2030 to mitigate the climate change. Based on data from BPS, Indonesia's renewable energy mix in 2021 is 12.16% with a target of 23% in 2025. This indicates that there are challenges faced by Indonesia in many sectors, especially the upstream oil and gas industry as one of the largest emitters of greenhouse gases, in achieving the energy transition target. In this study, trend analysis and data forecasting were carried out using trend analysis of time series data on oil and gas energy supply and consumption data as baseline to propose scenarios for both consumption and utilization energy to achieve net zero emission (NZE) in 2060. This study found that NZE may be achieved by applying energy consumption scenarios including the use of electric vehicles by 10% in 2030, and 90% in 2060 and the use of electric stoves by 25% in 2030, and 90% in 2060. Renewable energy utilization scenarios include geothermal (50%), hydro (50%), mini hydro (50%), solar (80%), and wind (15%) of the existing potential. In addition, early retirement for coal-fired power plants is needed .


Introduction
The rapid population growth, economic growth, energy prices, and technological developments have led to increased energy demand worldwide [1].Its also increases carbon emissions which causes climate change to get worse if the energy sources still coming from fossil energy base.In Indonesia, the energy mix still heavily dominated by fossil energy which is oil and gas contribute 51% and 38% from coal in 2021, which still significantly cause increasing of greenhouse gases (GHGs) emission and other environmental problems [2].
In 2011, Indonesia has a target of reducing GHGs emission production by 26% by 2030, which is also stated in Presidential Decree No. 61 of 2011.To achieve this plan, the implementation of Regional Action Plan for Reducing GHGs (RAN-GRK) are required.In addition, in 2016 Indonesia has signed the Paris Agreement and set new targets for reducing GHGs emission.In accordance with the Nationally Determined Contribution (NDC), the Government of Indonesia seeks to reduce emissions by 29% (without assistance) or 41% (with international assistance) in accordance with the Business as Usuas (BaU) scenario by 2030.The Government of Indonesia also initiated a Low Carbon Development plan for the integration of climate change regulatory mitigation that will be adapted to the National Development Plan [3].
Based on data from the Ministry of Energy and Mineral Resources (MEMR), the utilization of national renewable energy in 2022 only reached 12.3% of the target of 23% by 2025 [2].It need new more strategy to accelerating GHGs reduction to achieve the target whether from demand side and supply side.Therefore, one solution that can be done to achieve targets in accordance with the Paris Agreement is to implement the use of technology based on the context of renewable energy on a large scale.The concept of using 100% new and renewable energy has also become a global ambition that is planned to be applied from a corporate scale to a larger scale.Even as a country with a total energy contribution of 36% to the total energy supply in ASEAN, Indonesia's contribution to reducing the amount of emissions both on an ASEAN scale and on a global scale is something that really needs to be considered [4].
This study aims to provide an overview of carbon emission reduction using government strategies and additional strategies suggested by the author to achieve Indonesia's net zero emission in 2060 that presented as several scenario.

Data sources
This study used secondary data to prepare mitigation scenario and calculate CO2 emission for 2023 until 2060.The main data used in this study are supply and demand of energy in Indonesia that obtained from BP Statistical Review 2022 and Handbook of Energy & Economic Statistic of Indonesia (HESSI 2021) [2].Then to compare the result of forecasting supply and energy demand data will be validated with RUEN and publication from Institute for Essential Services Reform (IESR) [5].HESSI also consist of econometric and demographic essential data to create energy modelling and planning.Besides, the emission factor data obtained from MEMR [6] and another essential data i.e electrification ratio, power plant efficiency, and power plant construction planning were obtained from PLN [7].

Proposed scenario
Several scenarios that will be proposed in this study are an accumulation of several mitigation strategies to reduce GHGs emission nationally, as follows.1. Business as Usual (BaU) -Existing scenario from Rencana Umum Energi Nasional (RUEN) that released in 2017 and realization data for 5 years after RUEN was released will be projected as the baseline scenario.2. Government Mitigation Scenario (GMS) -Based on electric vehicle (EV) target used, city gas network, and biodiesel usage.3. High Optimistic Consumption Scenario (HOCS)-Maximizing demand of EV, usage of electric stove, biodiesel usage, and several energy supply strategy i.e cofiring hydrogen on Gas Turbine Combined Cycle (GTCC) power plant, and biomass cofiring on Coal Fired Power Plant (CFPP) 4. Middle Optimistic Consumption Scenario (MOCS) -Reduce EV usage target and the rest is same as HOCS.

5.
Middle Consumption and Renewable Energy Scenario (MCRE) -Periodic CFPP retirements, maximizing Indonesia's renewable energy potential, and the rest is same as MOCS.To see the different strategies used in each scenario, the strategy table is shown in Table 1.GHGs emission calculated from energy supply and demand forecasting result.Low Emission Analysis Platform (LEAP) software.The following energy model is used in Figure 1.Software used to obtained integrated result for supply and demand analysis, GHGs emission analysis that measured in CO2 equivalent, and made comparison for every single scenario.The LEAP model is the de facto standard for countries to undertake energy planning, integrated resources, greenhouse gas mitigation assessments, and low-carbon development strategies, the LEAP model is a model that meets the criteria for regional energy planning [1].

Result and discussion
Energy modelling simulations can be used to calculate the amount of emissions generated in terms of energy demand and energy supply.The increase in energy supply is in line with energy demand, while energy demand grows with the increase in population (assumed to grow at 1.22% annually), GDP growth, and urbanization rate.The energy demand is derived into 5 main sectors namely household, industry, transportation, commercial, and others.
Based on demand forecasting that has been done, the largest increase in energy demand is in the transportation sector, which increases from 381 MBOE in 2021 to 1058 MBOE in 2060 with an average increase of 2.65% per year.Thus projection has almost the same comparison with the results of research by Edwaren et al, which grew by around 2.8 times from 2019 to 2060 [8].Then from the transport sector, the use of gasoline is the largest, which is around 57.86% of all vehicle fuels.This is one reason why it is necessary to increase the usage of electric vehicles.
Based on the results of energy modelling, the emissions produced will still be large if the reduction is carried out only in the transportation sector, so the strategy also seeks to reduce emissions in all sectors that produce carbon emissions.The others strategy are usage of electric stoves to reduce emissions from the gas stoves, and the blending of biodiesel in diesel for industrial activities The following are the results of carbon emissions from the baseline scenario and each mitigation scenario as shown in Table 1.BAU scenario gives GHGs emission around 1.08 billion MT CO2eq.Where the amount of emissions is about half of the projected results by BPPT in Indonesia's energy outlook [9], but the realization of the increase in emissions in the study is too high if evaluated in 4 years after the study is made.The GMS scenario provides a 23.25% reduction in GHGs emissions from the BAU scenario.One of the additional mitigations simulated in the HOCS scenario is the use of electric stoves and also an increase in the target of using electric vehicles in 2050 and resulting a 29.02% reduction in GHGs emissions.However, the overly optimistic target use of EV in HOCS causes greater carbon emissions until 2034 than the BAU scenario.This is due to the increasing demand for electricity which is not accompanied by the use of renewable energy sources in electricity generation.Based   Based on table 2, the usage of EV provides the largest reduction in emissions from the demand side.While the use of electric stoves is much smaller.This is because gas stoves produce lower emissions when compared to motorized vehicle emissions.Besides, blending biodiesel does not have a significant impact because the carbon emission factor of B50 is 0.77 gram/km when compared to diesel fuel which is 0.88 gram/km [10].Moreover, the availability of biodiesel needs to be reviewed to be able to meet the demand as a mixed fuel in 2050.Likewise, the cofiring of Ammonia is not significant because the share of GTCC is fewer than CFPP.Cofiring 20% biomass on CFPP has a slightly significant impact because the amount of CFPP is very large in Indonesia.Biomass cofiring has several limitations, including the availability of biomass and the effect of biomass burning in the boiler [11].
GMS, HOCS, and MOCS scenarios lead to an increase in electricity demand.Therefore, the electricity supply must come from New and Renewable Energy (NRE).By utilizing the potential for electricity generation from NRE in Indonesia, MCRE scenario reduce carbon emissions around 68.74%.But a deeper study is needed related to how to take advantage of the potential of such a large NRE in Indonesia.Then, if we trace the remaining carbon emissions in the MCRE scenario, Table 3 displays emissions that still need to be reduced.Reducing carbon emissions from energy modeling can only be mitigated through patterns of energy consumption and energy supply [12].However, from these two aspects, emission reductions are projected to be unable to reach Net Zero Emissions by 2060 for the reasons mentioned earlier.Therefore, other mitigation steps outside these two aspects are needed to reduce carbon emissions.One of them is by capturing, storing, and utilizing carbon emissions generated from the industrial sector, especially the oil and gas industry or commonly referred to as Carbon Capture Storage / Carbon Capture Utilization and Storage (CCS / CCUS) technology [13].
Based on the NRE energy transition scenario, emissions generated from oil refinery activities in 2060 will be 17.78 MTon CO2e and in the power generation sector it is predicted to be 95.29 MTon CO2e.Emissions at this power plant come from the continued use of natural gas, diesel, and biodiesel in their energy sources.Meanwhile, in the aspect of energy demand, there are 173.56MTon CO2e consisting of sectors as shown in Table 3.
So if the need to absorb carbon emissions by 2060 to reach NZE is 285,701 MTon CO2e.For CCU/CCUS, it can be applied to the energy consumption sector in industry and the energy supply sector in this case is power plants and oil refineries.So that the total need for CCU / CCUS in 2060 is 145,206 MTon CO2e.To reduce carbon emissions in transportation sectors such as buses, trucks, ships, and planes rely on the development of technology to reduce emissions and sequester CO2 naturally such as preserving forest [14].That way, by 2060 by using mitigation measures in the NRE scenario and the construction of CCU / CCUS with capacity above will be achieved Net Zero Emission.

Conclusion
Net Zero Emission in Indonesia may be achieved by applying energy consumption scenarios including the use of electric vehicles by 10% in 2030, and 90% in 2060 and the use of electric stoves by 25% in 2030, and 90% in 2060, biodiesel mix by 2050 for B100, ammonia cofiring in GTCC, and biomass cofiring in CFPP.Renewable energy utilization scenarios include geothermal (50%), hydro (50%), mini hydro (50%), solar (80%), and wind (15%) of the existing potential.In addition, early retirement for coal-fired power plants is needed.

Table 1 .
Table of Mitigation Scenario.
, the target of EV usage was lowered in the early period due to the large amount of electricity generated from coal.Therefore, in MOCS, the target of electric vehicle usage was lowered to 5% in 2030 and 25% in 2040.This scenario provides a 25.54% reduction in GHGs in 2060.The reduction of the electric vehicle usage target also considers how the development of supporting infrastructure and increased public interest in EV usage.To see the effectiveness of each strategy in reducing emissions from the energy demand side, the following table shows the reduction of each strategy in MOCS scenario.

Table 2 .
GHGs Emission Reduction each Strategy in MOCS.