Indonesia produces large amounts of organic waste that, to avoid environmental contamination, must be carefully managed. Currently, most of this material is viewed as just that, waste. The reality is that it is a resource that is being overlooked and underutilised, or put simply, dumped.
After Saudi Arabia, Indonesia’s population is the second largest organic waste generator in the world, with over 60% of solid waste being food. In terms of agriculture, it has been estimated that from animal waste alone, around 10,000 MNm3/year of biogas, enough to generate up to 1.7 x 106 kWh/year of electrical energy, could potentially be produced from this waste. If biogas from the treatment of the effluent from the production of palm oil and cassava are included into the mix, the potential for power generation and the displacement of fossil fuel energy sources increases by a further 1,800 MWh/year.
Indonesian agroindustry generates significant quantities of organic waste. In many cases, this waste is viewed as a commercial disincentive in that disposal routes which result in an operational loss continue to be employed. The organic fraction of landfill, sewage sludge, and effluent from palm oil and cassava mills are also waste streams that, instead of representing a cost centre, should be viewed as an additional value stream for any business whose main activity is not waste management.
Anaerobic digestion is a tried and tested technology that can be adapted to handle large or small volumes of material and has successfully been deployed in many projects around the world. It is rapidly becoming the preferred technology for providing a solution as to how to manage the considerable volumes of organic material whose current destination terminates in landfill, a disposal method that is quickly becoming the trademark of a society that does not appreciate the value of their own resources. Of course, anaerobic digestion of organic waste is not only a way to manage waste and reduce contamination, it is, as has been pointed out above, also a mechanism in which significant quantities of biogas can be produced.
Agriculture, and industries allied to it are the main potential beneficiaries of the implantation of anaerobic digestion as a mechanism for large-scale treatment of organic waste and the conversion of what is generally considered to be a problem into a resource. The biogas produced can be collected and cleaned, then used as an alternative to fossil fuel, the digestate can be further processed to be used as a fertilizer and the treated water from an anaerobic reactor, once it has been treated to comply with the discharge consent, can be released to the watercourse.
Although important in this sense, anaerobic digestion is not merely a mechanism to benefit only the shareholders of the enterprise by recovering value from the waste stream of any given industry, it is also a mature technology designed to avoid contamination and improve the public perception of the project, a commercial strategy that will, ultimately, result in increased sales from consumers who demand environmental responsibility.
Biogas production in Indonesia is an increasingly important and attractive option both for reducing the operating costs of industrial plants and for reducing greenhouse gases to the environment. In particular, palm oil mills generate large amounts of both solid and liquid wastes, and it is the effluent, or POME, that has been singled out by the operators as the most expensive and difficult to manage.
The normal method of dealing with the large volumes of effluent resulting from such operations is that of capturing the effluent in a covered lagoon. Palm oil mill effluent lagoons can be converted into efficient anaerobic digestors that not only reduce the organic loading of the effluent but can also produce commercial quantities biogas for on-site power generation or for export to the national grid.
Palm oil production relies heavily on the use of water with about 0.5-0.75 tonnes of POME being generated for every tonne of fresh fruit bunch (FFB) processed. If released directly to the environment, raw POME depletes water bodies of oxygen and kills aquatic life. Added to this, in Indonesia, palm oil mills have been cited as being a significant source of uncontrolled methane release to the environment. If this is extrapolated across an increasingly important global industry it is clear that palm oil production, apart from the bad press the industry has even before pollution is considered, constitutes a major contributor to the balance of global warming gas emissions.
The principal characteristics of POME are the high levels of COD and BOD entrained within it. Anaerobic digestion, and the production of biogas involves the breakdown of organic material in an oxygen-free environment. Under anaerobic conditions, methanogenic bacteria flourish, and both COD and BOD are significantly reduced at the same time as commercially significant quantities of methane gas is produced. For this reason, anaerobic digestion has been increasingly employed for the treatment for wastewater, as the methane produced can not only be used to generate power but also the reduction of greenhouse gases can be used as a mechanism for carbon offsetting.
In the production of biogas from POME, anaerobic digestion equipment consists, in simple terms, of an anaerobic reactor volume, a gas holder to store the biogas a mechanism to clean the gas of highly toxic elements such as H2S and, if electricity is to be produced, a biogas-fuelled engine and generator set.
Organic waste is broken down in the anaerobic digestion reactor, with up to 60% of this waste being converted into biogas although it is important to stress that the rate of breakdown depends on the nature of the waste, the reactor design, and the operating temperature.
The process of anaerobic digestion (AD) for biogas production consists of three principal steps. In the case of POME, the first step is the decomposition (hydrolysis) of organic matter. This step breaks down the organic material to usable-sized molecules such as sugar. The second step is the conversion of decomposed matter to organic acids. Finally, the acids are converted to methane gas. Process temperature affects the rate of digestion and, in order to avoid process interruption, it should ideally be maintained in the mesophillic range (30ºC to 35ºC).
Palm oil production is an important commercial activity. However, in order to ensure that the economic viability is optimised, it is incumbent on producers to engage in the development of sustainable practices that also ensure environmental protection. By using techniques that can convert waste material into an economic resource whilst also reducing the environmental impact, there is little reason why palm oil cannot be perceived as being a benefit both to the local community and to humanity rather than a liability.
Over the last thirty years, the use of biogas as a renewable fuel source has not only become a well-understood field of expertise, it has also become an attractive investment as it fulfils many of the criteria laid down by legislation designed to meet International targets of reducing GHGs (Green House Gases). Even with the rise of scepticism on the part of influential legislators, the momentum, in terms of transposing the basis of our base energy supply, appears to be unstoppable. Biogas, and its use as a viable fuel, offers a small but important component within the armoury of weapons being deployed against the increasingly evident threat of climate change.
Biogas is generated by the degradation of organic waste produced by agriculture, or by the accumulation of organic material from urban waste in landfill sites. Traditionally, it is an environmental problem in that methane, a major component of biogas, is highly explosive and is more than 21 times more effective as a GHG than CO2. However, the many projects that have successfully used biogas to generate energy, mostly in the form of electricity, and thus reducing its uncontrolled release to the atmosphere, have clearly demonstrated that biogas projects are a viable alternative for both increasing renewable energy capacity and directly removing a highly toxic GHG from the environment whilst, at the same time, displacing the use of fossil fuels as a primary fuel for energy production.
Legislation for controlling biogas (or, to focus on its main active component, biomethane[1]), which effectively legitimises its place within the spectrum of fuels that can be employed for the generation of energy, has been enacted at both national and international levels in many countries around the world. The purpose is not only to reduce environmental contamination but also to promote its use as a mechanism to ensure that legally binding environmental targets are met.
Indonesia’s reliance on fossil fuels to meet increasing domestic energy demand has made it among the world’s largest greenhouse gas emitters[2]. Following ratification of the Paris Agreement, Indonesia indicated that it would be targeting a 26% and 29% GHG emission reduction rate by 2020 and 2030 respectively. This, unfortunately, is some way from being achieved as, over the past five years, energy generation using coal has increased by around 12.2 GW. This compares with only 1.6 GW of renewable energy and planned capacity additions for renewables have been slashed in favour of coal[3].
Indonesia produces a large amount of organic material that is currently being underutilised or simply dumped. There is little doubt that biogas offers significant environmental and social benefits as a locally generated energy source throughout Indonesia.
Like any other engineering project, a biogas-to-energy project should be subject to a thorough risk assessment prior to being developed. This generally falls into two sectors: technical and commercial.
In terms of the commercial side, renewable energy initiatives are indeed being developed by private companies in Indonesia but there is less investment in the biogas-to-electricity market mainly due to a generally unsupportive legislative environment for biogas-for-electricity projects. Biogas power plants have relatively high initial set-up and operating costs and, if there is no effective feed-in tariff or little possibility for a private purchase agreement between a power generator and a user, commercial incentives for developing such projects are low.
Because of the level of accumulated technical experience in developing biogas to energy plants, this type of project can be considered to be ‘low-hanging fruit’ in terms of the development of renewable energy capacity. Waste organic material is only set to increase, and it has been estimated that about 9,597 Mm3/year of biogas could potentially be generated from animal waste alone in Indonesia, a production that could be utilized to generate electric power up to 1.7 × 106 KWh/year[4].
With regard to the technical experience in the collection, treatment and preparation of biogas for use as a fuel, the technology has improved considerably since the days of sticking a pipe into a pile of rubbish and lighting the gas stream with a petrol-soaked rag. However, in terms of risk analysis, this type of project is not without its own peculiarities. It is now recognised that, in order to ensure that the technology risk of a biogas project is adequately mitigated, not only must the correct procedure for project assessment be followed, but appropriate techniques and equipment for treating and using the gas must be employed.
A biogas-to-energy project is one in which there are several subsets of expertise necessary. These include gas resource assessment, gas collection, treatment and preparation; as well as control, use and long-term operation of all equipment.
A biogas-to-energy project commences with resource assessment, a critical phase of the project in which all aspects are considered, and both financial and technical modelling are calculated, checked, and verified.
If the result of the assessment is positive, project planning proceeds to the technical aspects of gas management and energy production, two areas that whilst requiring differing technical abilities are not mutually exclusive. An experienced developer will ensure that the relevant skills are inbuilt into the structure of the project, as a lack of one area of expertise can lead to significant downtime and a concomitant loss of income.
Biogas to energy projects, indeed renewable energy projects in general, are of increasing interest not only as a mechanism of reducing GHGs but also as a means of mobilising local employment. It remains to be seen whether Indonesia’s local or national governments can be persuaded to see the benefits of this type of project, both in terms of social development through local employment and skill development, as well as the significant environmental advantages through a cut in GHG generation from using a potentially plentiful supply of waste biogas instead of fossil fuel in the production of electricity.
In many parts of the world, the treatment and use of biogas are now considered to be a mature field of technological innovation. Nevertheless, the potential of biogas as both an alternative fuel source and an effective mechanism of environmental amelioration continues to attract attention. To explore some of the aspects of this interesting sphere of engineering, Organics, partnering with Euroasiatic, will present a webinar focusing on biogas handling, processing and preparation, and will relate their experiences in equipment and engine management.
The webinar will comprise two components: in the first, Organics will look at how biogas is generated, controlled and prepared for use as a viable fuel; in the second Euroasiatic will address the use of biogas in gas engines. Their discussion will be highlighted with several of the many examples of successful projects that have been installed around Indonesia.
[1] Biomethane is a naturally occurring gas which is produced by the so-called anaerobic digestion of organic matter. Chemically, it is identical to natural gas. https://www.biomethane.org.uk/
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