The opening of Singapore's newest incineration plant was significant in two ways: it is the first incineration plant to be built and operated by the private sector in Singapore and the first to be smaller than each of its predecessors. Indeed, it is Singapore's smallest MSW incineration plant ever to be built.
Chinese drums and two symbolic dancing lions led in the official launch party, which included the deputy prime minister and minister for defence, Mr Teo Chee Hean and the minister for the environment and water resources, Dr Yaacob Ibrahim. The official opening was timed to coincide with the bi-annual World Cities Summit in which Singapore's National Environment Agency played a significant role.
Under Singapore's policy to encourage greater p
can generate up to 20MW of renewable energy to go into the national grid.
Previously all of Singapore's incinerators have been constructed and operated by the NEA. The island's first four incineration plants were built between 1979 and 2000 with the capacity of each one getting increasingly greater each time in order to accommodate ever increasing and more rapidly rising amounts of waste from all sources of waste generation. The sequence of building of the Singapore incineration plants was:
- the first, Ulu Padan had a capacity of 1,100 tonnes per day (tpd);
- then with a higher capacity of 1,700 tpd, the Tuas incineration plant;
- the third, Senoko with 2,400 tpd capacity;
- fourth, Tuas South with 3,000 tpd capacity.
The NEA has also divested itself of the third incineration plant, the Senoko plant, which is the only incinerator plant in the Eastern part of the island. This plant is September 2009 was taken over to be operated by Keppel Seghers as part of the PPP initiative.
The New Tuas Incineration Plant
Due to Singapore's success in recycling more wastes and its first efforts at waste prevention, the first of Singapore's waste incineration plants has now been replaced. The newly opened plant's design capacity is even lower than Singapore's first plant at 800 tpd through the NEA's design, build and operate contract. The new Keppel Seghers' Tuas plant became fully operational in October 2009 after its successful commissioning trials.
The new Tuas plant is built on a site in the extreme south west of the island of Singapore, immediately next to the existing 3,000 tpd plant operated by the NEA. Originally the NEA planned to build a duplicate 3,000 tpd plant on that site at some point when demand warranted in order to accommodate the then projected increases in waste generation in Singapore. The NEA then expected that the new plant would be built well within ten years of the building of the opening of the NEA's South Tuas WtE facility.
The first incineration plant built in Singapore was at Ulu Padan and was opened in 1979, which is a decade after the Greater London Council's Edmonton incinerator started its operations, although Edmonton has had to be progressively upgraded in order to meet ever tighter EU emission targets. The Ulu Padan plant was closed down in August 2009 but the old girl in North London keeps on going.
The reason for Singapore going for incineration as its primary option for waste treatment and disposal in the 1970s was emphasised by the deputy prime minister, Mr Teo Chee Hean, in his speech when opening the new plant: “With just 700 km2 and a high population density Singapore needed to find an alternative to the land-intensive method of landfilling waste”.
This is in contrast to Hong Kong, which faces very similar issues regarding its waste management system, for example. Hong Kong has opted for the continuation of the landfill of residual waste. This is due to public opposition to incineration and therefore the Hong Kong government has extended the life and some of the land requirements of its four existing landfill facilities for the acceptance of waste.
This aspect of saving land resources in Singapore was further emphasised by Mr Michael Chia, the deputy chairman and CEO of KIE (Keppel Integrated Engineering, within which Keppel Seghers forms its environmental engineering arm), in his speech at the official opening. The plant occupies only 1.6ha of land to “support NEA's aim of building a sustainable quality environment in land-scarce Singapore by incorporating many space saving and technologically advanced features”.
Keppel Seghers is a local Singapore company and part of the Keppel Corporation, which has built, and is building, WtE plants in other parts of the world. There are plants being constructed in the Middle East but not surprisingly especially in China, where, in 2010, Keppel Seghers announced three contracts totalling £40 million to provide technology and services for WtE plants in Guanzhuang (Tianjin), Shenzhen and Chengdu.
Manchester
Of greatest interest to those in the UK is that Keppel Seghers has won the contract for the 420,000 tpa WtE plant to be built as part of the Greater Manchester Waste Disposal Authority's PFI contract. Keppel Seghers was awarded the contract to design, build and provide the technology for the WtE CHP plant for Ineos Runcorn TPS Ltd, a special purpose vehicle which was set up for the procurement, operation and maintenance of the plant.
When completed, the plant will treat up to 420,000 tpa of solid recovered fuel (SRF), and also the digestate from the Greater Manchester AD plants, which will be processed from Greater Manchester's residual municipal waste. The Ineos Runcorn plant will produce 270,000 MWh of electricity and approximately 500,000 tpa of steam. The whole of the energy output from the Keppel Seghers' plant will be utilised by the neighbouring chemical manufacturing plant.
While the Ineos Chlor plant will be 50% larger than the new Singapore plant there are a number of features common to the two plants, including: the water cooled multi-stage grate design, the boiler and the double dry flue gas treatment system. The single electricity generator of such plants, which is a common feature in plants of this size, is also similar. The Ineos Chlor is naturally bigger at 35.8MW. The smaller 22MW Singapore plant's generator was purchased from Siemens.
The Tuas generator can therefore provide up to 22MW of electrical output at a maximum for the grid but on average will provide an output of 17MW of electricity to the grid on an annual basis. This output is in addition to the electrical demands of the plant's own requirements.
One of the design features of the Singapore plant was the combustion grate configuration which allows for effective mixing of waste for efficient combustion through a mix of tiles (slats) within the grate, some of which are fixed and others capable of moving the waste in either one or two dimensions. According to Prof Jim Swithenbank from the Waste Incineration Centre based at Sheffield University, who accompanied me on a tour of the plant after the official opening, purely from visual inspection of the ash at the end of its traverse through the grate, the burn out of the waste was good with ash content probably having a very low carbon content.
Once the waste has been reduced to 10% of its original volume within the Tuas plant, the IBA (incinerator bottom ash) is transferred into a barge and then transported to Singapore's only landfill, Semakau. This transfer is through the Tuas Marine Transfer Station which is integrated into the neighbouring South Tuas incinerator. The 2% of Singapore's non-combustible waste also sent directly to landfill, plus the IBA currently consigned to the Semakau landfill mainly goes through this transfer station.
The Semakau landfill site was constructed in the 1990s as a land reclamation project with a 7km bund enclosing two small islands producing a 350ha site with 63m m3 capacity. Fully lined and carefully engineered it was initially expected to last Singapore for 20-25 years before a further landfill facility needed to be developed.
With the reduction of waste being sent for landfill, the Semakau site is now expected to last 35-50 years. This timeline ought to become potentially substantially longer if the IBA is recovered and utilised as a secondary aggregate, as is common in many EU countries. The NEA has already undertaken studies to assess the potential application of processed IBA for a range of civil engineering purposes.
Singapore's Waste Management System
Vaneeta Bhojwani, deputy director (industrial development) for the Industry Development and Promotion Office of the NEA explained that when the 'Singapore Green Plan 2012' was adopted as its waste management strategy Singapore wanted to follow the principles of the waste hierarchy in order to ensure that Singapore's non-recoverable waste was reduced to an absolute minimum. However, the main target on which the NEA and the population of Singapore have focussed was to reach a 60% recycling rate for the island's waste by 2012.
The most recent NEA Annual Report, for 2008/09 shows that overall there is still a gap to be bridged in order to reach the 60% recycling target. With regard to cutting the link between the generation of waste and the growth of GNP per head Singapore may just be hitting the target, a significant achievement compared to its nearest neighbours. However, within Singapore there is a small but gradual increase in the amounts of waste being disposed of through the NEA's facilities. Therefore the 2004 amount of waste from domestic and commercial sources of just under 4,000 tpd has risen to more than 4,000 tpd and likewise the industrial waste amounts have grown from just under 3,000 tpd to just over 3,000 tpd.
With regard to the ultimate disposal routes, excluding the wastes sent for recycling, a mere 180,000 tonnes went directly to landfill in 2008 while 2.45m tonnes went through the four incineration plants. In addition, the recycling rate, which covers the whole range of waste categories, has risen from 54% in 2007 to 56% in 2008.
Outputs from the first four incineration plants included 1,048 kWh of electricity in 2008 and the amount is expected to increase slightly each year due to operational efficiencies within the incineration plants. This electrical output represents around rather less than 3% of the island's electricity consumption, a figure which is similar to that which could be generated from the UK's residual waste if the UK were to establish the full range of WtE facilities, which would be necessary to maximise the utilisation of the UK's energy potential from its residual waste, unless the UK were to introduce substantive energy saving and efficiency measures. These statistics demonstrate the need to both introduce more energy saving and to establish renewable energy measures in both Singapore and the UK.
More than 11,000 tonnes of scrap metal is reclaimed from the IBA each year and sent through to a local steel works for reprocessing. Through the success of its waste reduction and recycling measures Singapore will be able to extend the time for replacement of its other incineration plants. However, all future plants are likely to be contracted out as the NEA devolves direct responsibility for waste disposal operations to the private sector through the PPP initiative.
Singapore has an enviable waste management system, certainly comparable to the best that the EU can demonstrate
Jeff Cooper, ISWA
Raising the recycling rate beyond its Green Plan target of 60% by 2012 will be difficult because unlike the UK in Singapore there is currently no landfill tax. In Singapore there is a long-standing uniform disposal cost of S$77 (£35.00) per tonne both for landfill and incineration, based on the real long-term costs of operating and administering the whole waste disposal system. However, the NEA has recently tendered for a contract to assess whether a landfill/waste levy would be beneficial environmentally. The main beneficial effect of introducing a landfill/waste levy would be to improve the opportunities for greater waste reclamation and recycling for waste companies in Singapore.
Low costs
The Singapore companies which try to reclaim more waste consistently argue that industry finds the cost of waste management and disposal so low that few industrialists are concerned about using their services, particularly because it would mean having separate containers for recyclables and one for the residual waste. Changing the cost structure for waste management would allow more opportunity for specialist reclamation and recycling companies to offer more services. However, the NEA's study will also deal with the difficulties which a landfill levy will present as well.
Overall, Singapore has an enviable waste management system, certainly comparable to the best that the EU can demonstrate. However, at present it stands as an isolated beacon in a region where the standards of waste management are still to be established, let alone implemented. Even within Singapore, however, there are many opportunities to enhance its progress to achieve the ambitious objectives incorporated into the 'Singapore Green Plan 2012'.
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