Energy-producing waste treatment technologies-
Southeast Asia has tremendous potential to produce energy from the biomass residues of solid waste, the wood processing and cement industries, and agriculture. The rapid pace of urbanisation and industrialisation in the region has added urgency to the need to develop advanced waste-to-energy (WtE) technologies for efficient biomass/biogas utilisation. According to industry estimates, the region produces over 230 million tonnes of biomass per annum, which has the potential to generate 16–19 GW of power. However, most cities in the region lack proper segregation, transport, and storage facilities to tap into this potential. Only Singapore and some metropolitan cities in Indonesia, Malaysia, and Thailand have waste collection rates of more than 80 per cent. Moreover, in most cities in the region, collection services are not extended to unauthorised and remote settlements, which are either inaccessible or lack the capacity to pay for these services.
The WtE combustible segment holds huge potential to serve the twin goals of waste and energy management. In Southeast Asia, WtE facilities initially attracted a lot of criticism and protests from the public due to their possible environmental impact. Despite that, a number of WtE facilities were set up in Singapore, Thailand, Indonesia, and the Philippines. Today, Southeast Asia has a WtE capacity of over 20,000 tonnes per day (tpd) across its major cities. These facilities generate over 2,760 MWh of electricity per day. In addition, over 2,700 tpd of capacity is expected to become available in the next one–two years. The successful implementation of these facilities is expected to pave the way for further developments.
WtE technology options
Among all the feasible technology solutions, incineration is the most commonly used technology in the region. The incineration process involves complete oxidation of waste under high temperatures and aerated conditions. At present, mass burning systems and refuse derived fuel (RDF) systems are the two technologies used to produce energy through incineration.
The incineration process is characterised by relatively low capital and operating costs. Besides, it drastically reduces the weight and volume of solid waste to be disposed of at landfill sites. From the environmental point of view, this process can directly reduce the amount of greenhouse gas emissions from landfills.
Some of the largest waste treatment plants in Singapore, Indonesia, and Thailand use this technology to produce electricity from municipal solid waste (MSW). Singapore has led the way by setting up four incineration plants with a combined capacity of 7,900 tpd for solid waste treatment and energy generation. According to the latest available data (2013), Singapore generates 19,862 tpd of solid waste, of which 60 per cent (11,846 tonnes) is recycled, 37.5 per cent (7,455 tonnes) is processed at incineration facilities, and another 3 per cent (541 tonnes) of waste that cannot be incinerated is disposed of at a landfill.
The Tuas South incineration plant is the city-state’s largest incineration facility, with the capacity to process 3,000 tpd of solid waste, and produces about 150 MWh of electricity per day. The three other incineration plants in Singapore are the Tuas incineration plant with a capacity of 1,700 tpd, the Senoko WtE plant (2,400 tpd), and the Kepple Seghers Tuas WtE plant (800 tpd).
Singapore’s four incineration facilities currently produce over 2,688 MWh of electricity per day from the burning of over 7,100 tonnes of waste. About 80 per cent of the electricity produced from these incineration facilities is sold to various industrial and commercial establishments, while the remaining 20 per cent of the energy is used to run the incineration plants.
Indonesia and Thailand are also using incineration technology to produce energy from solid waste. Thailand produces over 46 MW of energy from solid waste at present. Of this, 20.06 MW of energy is produced from incineration and gasification; 22.23 MW from gas at landfill waste; and 2.03 MW from biogas generated through waste fermentation.
In Jakarta, the capital of Indonesia, the city government used to operate several small incinerating machines in a number of villages to reduce the burden on the city’s largest waste treatment facility, at Bantar Gebang. However, the majority of these incineration facilities have been shut down primarily due to strong protests from local residents. The city government is now setting up a modern incineration facility at Sunter in North Jakarta, which is expected to manage some 1,200 tonnes of solid waste.
Another method of producing energy through incineration is by first converting waste to RDF. Unlike mass burning systems, RDF systems separate combustible waste from non-combustible materials such as metals, plastics, etc. before burning. Pre-processing waste before burning enables recovery of recyclables and segregation of wet organics. At present, the majority of the incineration plants operational in Southeast Asia use the conventional mass burning system to convert waste into energy. Some Southeast Asian countries have also set up a limited number of RDF plants to convert waste into alternative fuels. In Malaysia, the Kajang WtE facility, located approximately 13 miles from the national capital Kuala Lumpur, houses an RDF plant, which converts solid waste into fuel, and a steam power plant. It has the capacity to process approximately 1,100 tpd of solid waste into RDF and produces about 8 MW of electricity daily.
A few industrial players in the Philippines have established systems to convert solid waste into RDF that could be used in the cement-making process. For instance, a consortium led by the Lafarge Group has set up an RDF plant at the Payatas landfill facility in Quezon City. The WtE plant processes about 360 tpd of solid waste received at the landfill site. The RDF produced at the plant is used for the Lafarge Republic’s cement plants. Furthermore, in the province of Cebu, Apo Cement Corporation is being supplied RDF from the material recovery facilities in Naga City. Likewise, in Thailand, Siam City Cement Public Company Limited has set up a waste pre-processing plant to convert over 30,000 tpd of alternative raw materials, solid wastes, liquid wastes, and sludge into homogeneous RDF that is used as a resource for cement kilns.
While the incineration process dominates the WtE market, the anaerobic digestion process is also being used extensively by both industrial and municipal segments for energy production. This process involves biodegradation of organic wastes under strict anaerobic conditions. Electricity is produced from existing landfills through the natural degradation of solid waste by anaerobic fermentation (digestion) into landfill gas. The technology is being most extensively used in Indonesia. Bantar Gebang, the largest waste management facility in Jakarta, uses the sanitary landfill process with gasification landfill-anaerobic digestion (Galfad) technology to convert solid waste into methane gas. Currently, the facility treats the 6,000–6,500 tpd of garbage produced by households, industries, and commercial entities in the capital city. It produces about 10.5 MWh of energy per day. The design capacity of the plant is 26 MWh per day, which is expected to be achieved in 2023.
The intermediate waste treatment facility in Cakung Cilincing, North Jakarta, that started operating in August 2011 also uses the anaerobic digestion process along with mechanical biological treatment technology to treat solid waste. Inorganic waste is recycled, while organic waste is fermented to produce electricity. Built on 7.5 hectares of land, the Cakung Cilincing facility treats about 1,300 tonnes of solid waste and produces about 4.95 MWh of energy.
At the Quezon City integrated disposal facility in the Philippines, a WtE biogas plant has been set up to produce green energy from solid waste dumped at the Payatas landfill site. The Payatas landfill handles garbage collected from about 300,000 residents of Quezon City. In July 2013, two additional 320 kW engines were installed to supplement the existing 236 kW engine at the biogas extraction plant. With this capacity expansion, the plant now produces an average of 750 kW of power from methane gas extracted from the landfill. The electricity generated is being sold to the Manila Electric Company at time-of-use rates approved by the Energy Regulatory Commission. The plant also provides free electricity to local residents as a part of the “Plantsahanng Bayan”, a special project of the local government, and to power street lights in the periphery of the integrated landfill facility.
Some industrial groups in Southeast Asia have set up WtE plants at their manufacturing units that use anaerobic technology to convert wastewater/solid waste into energy or other green fuels. For instance, Beer Thai has installed an anaerobic and aerobic wastewater treatment project at its Kamphaeng Phet plant in Thailand. According to the latest available data, the plant produces up to 30,000 normal cubic metres (Nm3) of biogas a day, equivalent to more than 20,000 litres a day of fuel oil. Other major brewers in the region have similar WtE projects.
In the province of Central Java, Indonesia, two bio-digesters – Kalisari I and II – have been installed to treat wastewater generated by 20 tofu production businesses. The wastewater generated by the industries is converted into biogas which is used as cooking fuel by residents. Every year, approximately 38 million cubic metres of biogas is generated by these bio-digesters, which is being supplied to over 45 households as cooking fuel.
There are also plans to set up WtE facilities based on anaerobic technology in Marunda (Indonesia) and Lian (Philippines) to convert municipal waste into biogas. The Jakarta city government is setting up a WtE facility at Marunda, which will have a design capacity to treat about 1,500 tpd of solid waste. The facility will be developed on 12 hectares of land, which will be integrated into the Marunda special economic zone in North Jakarta. Similarly, Aseagas Corporation is establishing a $50 million biomethane digestion plant in Lian, Batangas (Philippines). The plant will produce carbon-neutral fuel in the form of liquid biomethane by processing effluents of the Tanduay distillery. The company plans to sell liquid biomethane to commercial vehicles and public transport running on gas engines. The plant is expected to be operational by end-2015.
Besides incineration and anaerobic digestion, some of the other, less used technologies for conversion of solid waste into energy include gasification and biomass steam production. Although these technologies have several proven advantages, there are only a few success stories in the region. In Singapore, Sembcorp Industries has set up a woodchip-fuelled biomass steam production plant in Sakra district of Jurong Island, which processes waste wood to produce 20 tonnes per hour of process steam for commercial use. The company has commenced work on another WtE facility in Singapore. The facility will use industrial and commercial waste to produce steam for supplying to companies on Jurong Island. As for gasification plants, currently, London-based Waste2Tricity is working on two pilot plants in Thailand, which will use fuel cell systems to generate electricity from hydrogen gasified from MSW.
The way forward
A continuous increase in the region’s population coupled with increasing public health awareness and rising environmental concerns is expected to create substantial demand for WtE facilities. Technology providers, designers, and operators in the field are gearing up to meet the rising demand for WtE solutions. In fact, a number of foreign and domestic players like C&G Environmental Protection Holdings Limited (China), Waste2Tricity (London), BMH Technology (Finland), Procter & Gamble Co. (USA), Sembcorp Industries Limited (Singapore), and Aseagas Corporation (Philippines) are either already implementing WtE projects or are in talks with the concerned authorities in the region to sign new deals.
Another factor that would boost investments in the WtE segment is strong government support. Most governments in the region have come to recognise the importance of formulating and implementing prudent policies to encourage greater private investment in setting up WtE facilities. They have begun to take action to increase both waste recycling rates and WtE capacities. In Singapore, the government has introduced a national recycling programme and is providing incentives to large hotels, malls, and companies that manage commercial premises to encourage them to recycle waste. In Thailand, the government has run a number of campaigns to promote community participation in WtE projects, and waste sorting and recycling, and spread awareness about the benefits of these activities. The government has established the Energy Efficiency Revolving Fund to promote energy conservation by providing investment assistance to operators for setting up of WtE facilities.
As the WtE market matures, more advanced technologies and processes are likely to be developed to provide efficient and low-cost solutions. In fact, Singapore is already exploring new technologies to maximise benefits from its WtE initiatives. It is considering setting up an integrated waste management facility (IWMF) next to the upcoming Tuas water reclamation plant (WRP) to reap the potential synergies of the water-energy-waste nexus. As Ronnie Tay, Chief Executive Officer, National Environment Agency, Singapore highlighted in a media release published on June 3, 2014, “The IWMF is a strategic component of NEA’s long term waste management roadmap. It will help land-scarce Singapore to realise even higher levels of resource efficiency as the co-location of the IWMF with Tuas WRP will allow both NEA and Public Utilities Board to harness the potential synergies of solid waste and used water treatment processes. These synergies will keep the cost of solid waste disposal affordable in the long term.”
Nonetheless, for a major shift to occur there is need to not only augment waste collection and treatment capacities but also integrate them with WtE activities. Although there is an increasing demand for WtE projects, their implementation is constrained by insufficient waste feedstock, and limited collection and transportation infrastructure. Hence, governments, businesses, and residents in the region will have to work in collaboration to ensure that waste collection and transportation activities are carried out efficiently. Furthermore, some issues associated with WtE activities such as its environmental impact, likely public protests, scientific disposal of by-products, etc. will have to be addressed to secure the benefit of these initiatives.
