Optimizing of Renewable Energy Co-firing to Push the EBT Mix Target by 2025

Optimization of the utilization of renewable energy (EBT) must be carried out as part of an effort to raise sustainable development in order to meet the energy mix objective by 2025. Biomass is one of the renewable energy sources with considerable potential for development. Biomass is a carbon-based substance that can release heat when oxidized. When used as an energy source, biomass has various advantages, one of which is that it is renewable, allowing it to be classified as sustainable energy. However, the current use of biomass as an energy source is still very low, at 1,895.7 MW, or around 5.8 percent of its potential of 32.6 GW.

The government began to devise and implement several strategies, one of which was the co-firing program. Co-firing is the use of a certain ratio of coal and biomass as fuel while maintaining power plant quality and efficiency. In Indonesia, the co-firing program is stated in the 2019-2038 National Electricity General Plan (RUKN) as part of the Energy Conservation Roadmap on the energy supply side in power plants. The goal is to enhance the renewable energy mix. Because PLN’s PLTU capacity is relatively substantial, 31 GW or 50.3 percent of the country’s installed capacity, it has the potential to be used more effectively to reach the target. PLN intends to make transition of 114 PLTUs to co-firing by 2024. This co-firing approach will be enable building of a large scale biomass industry having capacity of consistently supplying of co-firing fuel ranging from 4 to 9 million tons per year. It is envisaged that this co-firing initiative will help Indonesia bridge the gap between the aim and the actual implementation of a renewable energy mix.

The solution is co-firing or co-combustion, which is the simultaneous combustion of coal and biomass in the combustion chamber of an existing large-scale power plant. An existing and operating coal fueled PLTU is more ideal for co-firing if its location is not too far from biomass source (less than 50 km to 80 km), lowering the cost of transporting biomass. Co-firing is more advantageous for low-quality coal, which is widely available in Indonesia. It is also more environmentally friendly. Meanwhile, co-combustion is proven to be more cost-effective for electricity generation. Furthermore, the combustion system at PLTU in Indonesia is generally suited for co-firing with biomass.

According to the combustion operation, there are at least two methods of co-firing: direct co-firing and indirect co-firing. Direct co-firing combustion process is simpler, coal and biomass are burned at the same time. While in indirect method, biomass gasification process needs to be done, prior to the mixing of those fuels in the combustion chamber. Theoretically co-firing with biomass does not add GHG, while the biomass grown in its natural state earlier, CO2 was absorbed during photosynthetic process of vegetations and trees. During co-firing combustion, in turn, CO2 then released to the air.