Siàƒ¢n Green, Managing Editor
Malaysia recently commissioned its first landfill gas power project at the Jana landfill site near Kuala Lumpur. The plant has attracted a great deal of interest, and will act as a blueprint for the development of similar projects throughout Southeast Asia.
In early 2003, construction started on a power plant at the Jana landfill site near Kuala Lumpur, Malaysia. Just one year on, in February 2004, the plant was commissioned and connected to the grid, marking the first time that landfill gas has been used to produce electricity in the country.
The 2 MW power plant consists of just two containerized gas engine units but represents a significant step forward for Malaysia, which is trying to increase the amount of electricity generated from renewable resources through its five fuel policy. Due to its large palm oil industry, the country has enormous potential for biomass-based electricity generation. According to Huan Hin Chan, general manager of JD Energy Systems Sdn Bhd which supplied the plant alongside UK-based Organics Ltd., generating electricity from landfill gas is another potential area of growth.
The power plant at the Jana landfill site in Malaysia is the first of its kind in the country
“Unfortunately, most landfill sites in Malaysia and other parts of Southeast Asia have no proper gas management or control,” says Chan. “We feel that it is a pity that such a good resource is wasted. If landfill sites were rehabilitated and controlled, we could do our part to help the environment.”
The methane gas that is generated by landfill sites is a greenhouse gas with a global warming potential 21 times greater than that of carbon dioxide (CO2). Allowing the gas to escape into the atmosphere therefore has environmental implications, but a lack of proper gas management can also result in fire and health hazards.
Driven by these factors, and understanding the potential for generating electricity from landfill gas, JD Energy has for several years been lobbying the government, local councils and national power utility TNB to promote an understanding of landfill gas power systems.
“Renewable energy is still very new in Malaysia so we have been doing a lot of promotional work such as conducting seminars and holding road shows to explain the advantages of renewable energy. We have also been working to gain the support of environmental groups,” explains Chan. “The government has recognised the scarcity of energy and the environmental implications of using fossil fuels, and wants to develop the renewable sector more. We felt that we could play a role in this by educating the market and getting the various NGOs, government bodies and developers to realise that using waste gas as a source of energy also benefits the environment.”
The development and completion of the Jana landfill is the culmination of this work, which Chan believes will result in more opportunities in landfill and the wider renewable energy sector. “The first project is always the most difficult but we expect it will take off on a greater scale.”
JD Energy is GE Jenbacher’s distributor in Malaysia and, together with Organics, supplied two 1048 kW containerized gas engine generating sets for the project. The two companies teamed up to respond to a formal tender issued by the developer, Jana Landfill Sdn Bhd (JLSB), a joint venture between TNB subsidiary TSPL and Worldwide Landfills Sdn Bhd, the company that operates Jana landfill. However, the tender covered only electromechanical equipment and the bids received were all higher than JLSB had anticipated.
Organics and JD Energy then approached JLSB with a proposal to do the whole project ” i.e. gas field and power island ” on a turnkey basis. This was accepted by JLSB and the two companies were awarded the contract.
This was a good decision on the part of JLSB because the gas field element of the project was “an interesting challenge”, according to Dr. Robert Eden, managing director of Organics Ltd. Initial talks indicated that there were no leachate problems on site, says Eden. “However, when we received the instruction to proceed, we did a complete site survey which showed that the site was saturated with leachate right to the top ” it was completely flooded.”
“We had to retrofit a leachate extraction system and that delayed us by about three months. We had to find a fabricator and get it built as quickly as possible.”
The decomposition process in a landfill lasts for about 15-25 years. The volume of gas production will decrease steadily over time after this period
The level of leachate in the landfill is not unusual in Asia, Eden said. It is primarily due to combination of issues, from rainfall through to the waste combination. The Jana landfill is under great pressure at present as it is taking the bulk of the waste from Kuala Lumpur.
High levels of leachate in the landfill will inhibit gas extraction. “If you have water there then you can’t get a sphere of suction around the well,” says Eden. “Normally you need a radius of about 20 m around the well but if it’s full of water then you won’t get any out.”
At the Jana site, Organics drilled a total of 25 wells to accommodate a combined leachate and gas extraction system. Each well is 25 m deep and lined with 160 mm casing. Eductors are inserted in the wells to extract leachate. As more leachate is drawn out over time, more gas can be extracted from the site.
Gas is extracted from the landfill, compressed, dried and fed into the gas engine
According to Chan, the gas emitted from the landfill is of excellent quality with a methane content of 50-55 per cent and a low hydrogen sulphide content. The gas is wet and must be dried before it is passed to the engines. Drying is done by absorption chillers which are fired by landfill gas to reduce the parasitic load of the plant.
As the engineering, procurement and construction contractors, Organics and JD Energy were responsible for the design and supply of the power station, the fuel skid and the gas delivery unit. The two engines are GE Jenbacher JGC320GS-L.L units.
The engines were supplied as pre-tested, containerized units consisting of engine generator, control unit and auxiliary plant. The engines are Jenbacher Type 3 gas engine gensets designed for landfill applications. The engine has 20 cylinders in a Vee configuration with a bore of 135 mm, stroke of 170 mm and total displacement of 48.7 l. The engine is fitted with GE Jenbacher’s proprietary LEANOx emission control system which is able to keep emissions and engine performance within designated parameters in spite of variations is gas quality and composition.
Changes in gas quality are inevitable in a landfill power system and the gas train of the engine is specially designed to accommodate this. Other modifications to the engines were necessary for them to operate efficiently in the hot, humid Malaysian climate, says Wilfried Bergmann, area sales manager with GE Jenbacher. In particular, the turbocharger has to be adjusted for the high ambient temperatures so that the engine does not derate. “If you run a turbocharged engine in high ambient temperatures you are limited because the higher the temperature of the air, the lower its density,” explains Bergmann.
“If the air is low density then the turbocharger cannot compress the air and goes into overspeed and is ineffective. So in hot countries the turbohousing and the turbo layout is adjusted.”
The engines’ radiators and air intake system are also adjusted for the high ambient temperatures, and air flow through the containers must be optimized to avoid ‘hot spots’.
Operation and maintenance practices must also be adjusted to account for the fact that landfill gas is the fuel. “Using landfill gas, operation and maintenance is a very important issue,” says Bergmann. “But with our LEANOx system we can achieve extended intervals between maintenance.”
GE Jenbacher has around 1000 MW of capacity running on landfill gas around the world, and the 320 engine is the Jenbacher unit most commonly used for landfill applications. This is because of its 1 MW-class size.
“Most landfills have a power output range of 4-12 MW, and once landfilling activity has ceased, gas production will gradually decrease over time,” says Bergmann. “So if you install 4 MW at the beginning of the project, it will fuel 4 MW for around 15 years and then only 2 MW for the rest. A fully containerized 1 MW-class engine is therefore a good size as the owner can easily remove it and transfer it to another site.
The Jana landfill power plant operates in parallel with the grid. Grid connection is achieved through an 11 kV step-up transformer.
One of the main challenges for Organics was the fact that Jana is still an operational landfill site. Jana, situated about 40 km outside Kuala Lumpur, receives around 4000 t/day of waste. “It was a difficult job for the landfill gas power station to interface with such a huge operation on the site,” comments Eden.
The power plant at Jana produces around 2 MWe, but gas production could support 6 MW or possibly more
Jana landfill is around ten years old and is already reaching its capacity. It is likely to be closed within the next year. The site will then be capped and will be able to provide the power plant with gas for around ten years.
The 2 MW power plant is currently using about 1000 m3/h of gas. However, the site is capable of supporting a much larger power plant of 6 MW ” equivalent to 3500 m3/h of gas. According to Chan, the first two units installed are being closely monitored by JLSB, and if they perform as expected then it is likely that the site will be expanded with more engines. The project has also generated a lot of interest from Malaysia and further afield.
“The project has attracted a lot of interest from around Malaysia and from other countries as well.” says Chan. “Countries such as Vietnam have taken a lot of interest in how the project has been developed and run. It is a good model plant that shows all the hard work we have done and it will give confidence to other people who would like to do similar projects.”
This means that other similar projects could follow both in Malaysia and other countries. Organics is already working on a new project as part of a consortium developing a 2 MW plant at a landfill in Ipoh, northern Malaysia. “We already have our renewable energy purchase agreement ” we have been offered MYR 0.168/kWh,” says Eden. “We are planning to start construction in a couple of months and we’ll finish towards the end of this year or the beginning of next.”
Projects such as these are being encouraged under Malaysia’s five fuel policy, which seeks to diversify the fuel mix in generation and encourage renewable energy. Developers of renewable energy projects are given tax incentives and receive up to MYR 0.17/kWh for the electricity they generate under a purchase agreement with TNB. Malaysia hopes that this will enable it to meet its target of a five per cent share in electricity generation for renewable energy.
GE Jenbacher’s LEANOx system uses the direct link between electrical power output, fuel temperature and boost pressure after the turbocharger to optimize combustion
This target is unlikely to be met in spite of the large potential for renewable energy in the country. The main problem is that the price offered for renewable energy under the purchase agreements does not provide sufficient confidence to counter the risk potential of such projects, says Eden. In Europe, for example, it has taken many years of operational experience to have the confidence to operate at similar revenue rates. It is almost inevitable that problems will occur as the industry develops industry in Asia, leading to excessive downtime and consequent loss of revenue.
It is a price that works on paper but not in practice. “In the renewable energy contract with TNB there is a penalty clause that penalises you if you go below 70 per cent of your declared export for one month,” explains Eden. “If your plant is down then you’re already earning less so you don’t need that penalty.”
Eden continues: “There is a lot of potential in Malaysia for renewable projects, but the price of electricity is borderline. If they increased it then that would transform the opportunity and transform the industry.”