London — Over the last 10 years, there has been a considerable change in biomass power generation in Asia. Indeed, owing to the scarcity and cost of biomass fuel, most power plants are in fact designed for multi-fuel and unconventional fuels. This creates several challenging issues in combustion and boiler maintenance, demanding improvised combustion technologies, modern fuel preparation and handling systems, for example.
In the last decade, several new approaches to power plant implementation and technology have also been introduced. Despite these challenges, the regional potential for agricultural and wood based multi-fuel biomass power plants is very high and the market is attractive. The highest potential in Asia exists in the sugar sector, followed by palm oil, rice, and wood industries and multi-fuel biomass power plants.
The most common and predominant biomass power plant fuels used in Asia are: bagasse, palm shell, palm fibre, rice husk and wood waste. Apart from these fuels, unconventional materials such as empty fruit bunches, corn cob, cassava rhizome, coffee husk and such like are also increasingly being used.
Left: The typical size of a biomass plant varies from industry to industry. In wood
industries 5 MW to 10 MW is usual.
Recently, the biomass fuel price in some parts of Asia has gone as high as US$60/tonne and this higher biomass fuel cost and unconventional biomass fuel usage is forcing developers to use more efficient multi-fuel boilers, turbines and peripherals. Efficient turbines with steam extraction for low and high pressure heat are also common these days.
Nonetheless, increasing demand for biomass fuel tends to lead to difficulties in projecting the availability of biomass fuels. And, even with multi-fuel boiler designs, there are cases where the fuel mix scenario changes from year to year. Such situations require advanced combustion systems to tackle varying fuel mix scenarios during the plant’s operational life time and the demand for such systems is very high. Project developers are thus being forced to look for innovative and creative approaches to reduce the initial investment cost and operational costs in order to make projects viable. As a result, those equipment suppliers with good engineering and design knowledge – especially in the use of unconventional and multifuel operation – are in high demand right across the region.
Biomass Combustion and Boiler Types
In Asia, travelling grate systems and reciprocating step grate systems are in major demand while fluidised bed combustion systems are also predominantly used in a few countries, but are not popular throughout the region. Vibrating grate systems are also in use at a few plants, but again, the technology has failed to gain widespread popularity. In addition, there are only a few installations of cyclonic combustion systems.
A decade ago, for new biomass power plants the most common steam cycle was in the range of 40 bar and 440°C. But these days, however, with the cost of biomass fuels high, more and more importance is given to high pressure steam cycles to increase the overall power plant efficiency. Consequently, steam cycles of 110 bar and 510°C are very common in new power plant projects.
Biomass Power Plant Capacity
The most common size of biomass power plants varies from industry to industry. In the sugar sector, for example, the most common power plant capacities are 15–40 MW, while in the palm oil sector the range is 5–15 MW and in the rice sector it is 5 MW or 10 MW. In wood industries, the typical size is 5 MW or 10 MW and in multi-fuel-fired projects the size ranges from 5 MW to 20 MW.
Smaller size power plant projects of less than 3 MW are not being tried much these days. Due to economies of scale the unit cost of investment ($/MW installed) for smaller scale projects is generally higher than that of a 10 MW scale project. As a result, such power plants are mostly viable only if replacing expensive diesel generation.
Power Plants In Water Scarce Areas
A typical 10 MW power plant requires around 1600 m3 of water for daily operations. Often such volumes result in approval delays from regulatory authorities and there is also a risk of planning rejection.
In water scarce areas, therefore, it is difficult to implement power plant projects using conventional designs. However, the use of air-cooled condensers, rather than water-cooled systems, means it is possible to implement a biomass power plant almost anywhere. Such air-cooled designs reduce the water requirement by around 80%, although the overall plant efficiency of the system is lower and the overall investment cost is higher. Consequently, air-cooled condensers are recommended only when considerable water scarcity issues arise.
Though the project implementation cost is much lower with separate procurement of equipment compared with that of EPC (engineering, procurement and construction) contracting, the project developers tend to go for an EPC approach in order to avoid dealing with the issues of warranty and other implementation delays. However, knowledgeable developers which have the capability to manage project implementation effectively prefer separate procurement to reduce the overall implementation costs.
Obtaining finance for biomass projects was a major problem until 2000 but today the situation is completely different. The wheels of finance have once again started to turn and there are many equity funds, investors, banks, financial institutions and venture funds available in the market looking for promising developments to finance. Several corporations are also coming into the business.
There is also a growing trend for project financing. Compared with corporate financing, project financing may be more difficult to secure, but the projects are generally of low risk, as banks will also ensure that all security arrangements are in place by conducting proper due diligence, before granting the loan.
Market For Boilers In Sugar Mills
Sugar mills in Thailand, Philippines, Indonesia and Vietnam have high potentials to upgrade their existing often outdated and inefficient cogeneration plants with modern, efficient, high pressure systems. In most of the sugar mills, the existing cogeneration system ranges from 21 bar and 340°C to 42 bar and 400°C. Some of the mills in these regions have implemented 67 bar and 490°C systems. However, there is the potential for very high pressure systems in the range of 87 bar and 510°C to 110 bar to 540°C. There are already several such projects operating in sugar mills around the globe.
Market For Boilers In Palm Milling Industries
Palm oil milling industries traditionally used palm fibre and shell as fuel. It was normal practice to dispose of the empty fruit bunches (EFB) without making any effort to reclaim energy from them. But, in the last 10 years, slowly, equipment suppliers have expanded R&D efforts and started implementing projects to burn EFB, which is a difficult fuel. Though several equipment suppliers have implemented such projects in Thailand, Malaysia and Indonesia, no-one has succeeded fully in this respect. Consequently, an equipment supplier which can bring in reliable and proven combustion systems can capture large markets in Malaysia, Thailand and Indonesia. Palm oil mill owners are carefully watching the technology development in this area and when satisfied that the technology is 100% proven, most of them will go for new plants which use EFBs. EFB fuel preparation systems is another area where opportunities are available.
Market For Boilers In Rice Mills
Rice husk is a difficult fuel compared with wood and bagasse due to its high silica content. The most commonly used technologies in Asia are traveling grate, reciprocating step grate and Fluidized Bed Combustion (FBC) systems. Cyclonic combustion and Circulating Fluidized Bed Combustion (CFBC) systems are also used.
Rice husk ash is mainly used in the steel industry as an insulator in the manufacture of forgings. The price of rice husk ash is quite high at the steel plant gate level (up to $400/tonne), as high quality ash is required for this purpose. The density, unburnt carbon content and moisture content of rice husk ash should be as low as possible. Rice husk ash is also used in cement industries. Research work is also going on regarding silicon chip manufacture from the residues. Boiler suppliers which can guarantee high quality rice husk ash are consequently in demand in Asia.
Market For Steam Turbines
The market for efficient high pressure extraction condensing turbines with multiple steam extraction is high in the sugar and palm oil industries. Rice mills have also increasingly started using condensing turbines with single steam extraction, mainly for paddy drying applications. High pressure condensing turbines are also in high demand. Back pressure turbines in existing sugar and palm oil industries are slowly being replaced by more efficient extraction condensing turbines.
Pollution Control Equipment
Pollution control equipment such as electrostatic precipitators (ESPs), filters and efficient multi cyclones are also in demand in Asia. Though ESP is most commonly used these days in new power plants, its performance over a long period of time is an issue as, in some designs, the efficiency slowly deteriorates resulting in higher emission levels. Suppliers which can give longer performance guarantee periods with different biomass fuels are thus in demand.
Left: Pollution control equipment, such as this electrostatic precipitator, is in big demand at Asian biomass plants.
As the potential for agricultural residues and wood-based power generation is high in the Asian region – and growing – it is becoming worthwhile for those companies from developed countries which have good technology and know-how to shift more of their commercial focus to this growth region. It is apparent that if the right entry and consolidation strategies are subsequently followed, then it is more than possible to capture a significant market share.
In the meantime, there has also been a considerable change in the mindset of biomass-fired project owners and developers in Asia. The implications of this key change cannot be undersated as they are now far more conscious about life cycle project cost and rather than going for cheap low quality equipment are moving to secure quality. This environment provides a level playing field for global equipment suppliers with good capabilities and knowledge.