AD Technology Offers Thorough Solution To Agricultural Wastes

In Indonesia, the problem of organic wastes have been getting more serious everyday. More than half of wastes taken to landfill areas (TPA) consist of food waste, market wastes, rotten vegetables, animal manures. Letting them accumulated, then the wastes will release methane into the air. This greenhouse gas has a global warming effect 28 times stronger than carbon dioxide.

In the meantime, Indonesia’s energy sector is still dealing with serious problems due to its dependence on LPG and fossil fuels. Such situation causes unstable energy prices for households and adds to the burden on the country’s energy balance. Given the country’s pledge to achieve net-zero emissions by 2060 and efforts to reduce emissions from waste, these two problems can be addressed with a single technological approach: anaerobic digestion (AD).

From Methane emissions to biogas production
Based on national data, Indonesia produces approximately 35-38 million tons of waste per year, 41% of which is organic waste. This organic waste is the main source of methane emissions from the waste sector, which is estimated to contribute more than 15-20% of total national methane emissions if not managed properly.

Anaerobic digestion (AD) is a technology that processes organic waste without any oxygen to produce biogas. In a tightly closed reactor, microorganisms break down organic matter through a multistep biological process that includes hydrolysis, acidogenesis, acetogenesis, and methanogenesis, resulting in the formation of methane gas, which can be used as an energy source. Technically, biogas from the AD process generally contains 50-60% methane with a potential production of 100-200 m³ of biogas per ton of organic waste. Recent research suggests that AD is increasingly efficient and adaptable to various conditions. Research published in Sustainability (2023) shows that biochar from the pyrolysis process of waste digestate from AD can help increase the efficiency of methanogenesis in organic waste.

A study from the Journal of Material Cycles and Waste Management also reports that the addition of biochar can increase methane production up to fourfold compared to without carbon additives. It demonstrates that AD is not a static technology, but continues to develop through research-based innovation.

However, the use of AD has limitations that should be honestly considered because the process is highly dependent on biological factors, and is highly sensitive to stable temperature, pH levels, and the type of waste feedstock. If operational conditions are imbalanced, biogas production can drop drastically or even cause its process to fail completely. The AD reactors must be also regularly maintained and technically managed to maintain their function.

Besides, costs and supporting facilities for families or villages remain a barrier, as it requires a relatively big amount of initial capital to build a reactor and a biogas distribution network. Therefore, implementing AD cannot be considered a shortcut as it requires technical planning, support from relevant institutions, and regular mentoring.

Economically, a household-scale biogas reactor generally costs around IDR 8-15 million, while a village-scale biogas reactor can cost IDR 100-300 million, with a payback period of 3-7 years depending on the price of replacement energy and the level of biogas utilization.

Support circular economy
The ability of AD to produce clean energy makes the technology a practical solution for households, villages, and small industries. The resulting biogas can be directly used to replace LPG in stoves. Global research from 2023-2024 indicates that agricultural, food, and municipal wastes have significant potential for processing with AD as a clean energy source. On a national scale, utilizing a small portion of household and industrial organic wastes has the potential to replace around 5-10% of LPG consumption, equivalent to hundreds of thousands to more than 1.0 million tons of LPG per year. Several village-level biogas initiatives in Indonesia and similar examples in India and Vietnam demonstrate that AD has proven to be applicable and capable for making communities more self-sufficiency in energy.

Besides helping provide energy, organic waste management also has a significant impact in preserving the environment and improving local economies. By directly processing organic wastes, the volume of wastes dumped in to landfills can be reduced by 40-60%. It will not only reduce the pungent odor and water pollution, but also prevents methane emissions that would normally be released into the air. Based on one estimate, methane emissions from landfills in Indonesia reach tens of millions of tons of CO₂e per year, making waste one of the main contributors to national methane emissions after the agricultural sector. The US Environmental Protection Agency (EPA) stated in 2024 that organic waste management is the most effective method for reducing greenhouse gas emissions from waste management.

From an economic perspective, AD effectively supports a circular economy. The solid residue from the AD process, called digestate, can be used as organic fertilizer. Several scientific studies have shown that applying digestate to the soil can increase the availability of key nutrients (1-3% nitrogen, 0.5-1% phosphorus, 1-2% potassium). It also supports soil microbial activity without damaging the soil structure, reducing dependence on chemical fertilizers and increasing crop yields by 10-30%. Therefore, the use of digestate opens opportunities for smallholder farmers.

Fertilizer production and energy import reduction
In addition to helping manage wastes sustainably, they can also obtain high-quality organic fertilizer. This way, organic waste is not only converted into energy but also returned to the agricultural sector as a productive input, forming an integrated waste-energy-fertilizer cycle.

In recent years, advances in the use of biogas through the AD fermentation process have opened up strategic opportunities to strengthen Indonesia’s national energy security. The potential for biogas from agro-industrial, livestock, and urban waste is considered enormous if utilized and could help reduce dependence on LPG and fossil fuels.

In the context of national energy, the utilization of biogas from organic waste in Indonesia is estimated to be equivalent to tens to hundreds of TWh/year, thus significantly contributing to the national energy transition and emission reduction targets.

With this, the energy sector will no longer be entirely dependent on imports. Communities can produce their own energy from household waste, market waste, animal manures, or local industries. This process introduces the concept of decentralized energy, where communities can become self-sufficient in their energy supply. This process opens up space for rural areas to become active actors in the national energy system, not just consumers.

Both central and regional governments have a crucial role to play to realize the potential. Policy support can take the form of incentive plans, initial funding for reactors, integrating the AD system with landfill management, and collaborations between local governments, universities, and industries, all contributing to the net-zero emission target. Widespread use of AD has the potential to reduce energy import costs by trillions of rupiah per year, while also reducing the burden of LPG subsidies and extending the operational life of landfills by around 5-10 years. Without clear policy and institutional support, AD technology could stagnate in the trial phase.

In essence, anaerobic digestion cannot be viewed solely as a technical solution for waste processing or biogas production. This technology is part of a major shift in Indonesia’s energy and waste management systems toward a more sustainable direction. Methane derived from waste is no longer simply a byproduct of decomposition, but rather a sign of a shift in our perspective on waste as a resource. Amidst the challenges of climate change and increasing energy needs, the development of anaerobic digestion represents a strategic momentum for Indonesia to transform problems into opportunities for innovation- and sustainability-based development, with significant national potential of biogas energy and the ability to reduce methane emissions by millions of tons of CO₂e per year. It can contribute significantly to efforts of achieving Indonesia’s Nationally Determined Contribution (NDC) and net-zero emissions targets by 2060. ^(*)