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Coal Water Slurry (“CWS”) Fuel: Alternative Fuel for Thailand

By Royal Daniel and Kasem Naknual – POWER Engineers Asia


Coal water slurry was initially developed in Russia about 80 years ago, and the technology was further refined in Europe in 1950. Due to low oil prices and huge oil reserves led to a complete stagnation in development and new application of the coal water slurry technology. Coal water slurry currently refers to the coal-based liquid fuel which reappeared in the 1970s when the world wide price of oil rose and the supply became scarce.

The main components of coal water slurry are coal, water, and additives inputted in the coal milling process to create a liquid fuel with similar flow properties as oil.  The coal water slurry can be produced to have the following properties: low ash, low sulfur, and low temperature of the combustion flame center.   The coal water slurry is a substitute for fuel oil and can provide high combustion efficiency, low discharge of ash, and have the environmental benefit of lower SO2 & NOx emission compared with solid coal fuel.

In the 2000’s, coal water slurry interest was rekindled in China to meet the Beijing Olympics environment challenges. Technology of coal water slurry and fuel in China has developed and matured rapidly.  It reached the international level and successfully passed engineering testing of coal water slurry for boiler use as an alternative to heavy oil.

In the United States, the US Army was tasked in 1992 to reduce its dependence on and consumption of petroleum (oil) fuel.  The US Army considered the feasibility of using coal water slurry as an alternative to the heavy fuel oil for boilers.

In 2014 the Thailand Electricity Generating Authority of Thailand (“EGAT”) is studying the feasibility to retrofit the 300 MW oil fired power plant at Krabi Province to use coal water slurry.  The coal water slurry is expected to convert the plant from a stand-by unit to a mid-merit unit for energy dispatch.  The coal water slurry will also add fuel diversity to the generation fleet which is currently weighted at around 70% natural gas fuel.

Coal water slurry may become a key technology for Thailand to help achieve the recently announced goal of a 40% fuel mix for coal set by the Government policy (before about 20%).  Coal water slurry can be used in the combustion process substituting for heavy oil for boilers offering the success of reduced imported oil savings and reducing the fuel cost to produce electric power.

The joint feasibility study between EGAT and Zhejiang University of China to retrofit the existing 300 MW Krabi oil fired Thermal Power Plant could become a major step for energy mix diversification for Thailand. Coal water slurry may allow Thailand to make a faster transition economically, away from Thailand’s limited resources of oil and natural gas, to the world’s most abundant resource of coal in an environmentally sound method. Coal based coal water slurry could be an alternative to heavy fuel oil making it a fuel of this century and beyond.

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