In 2007, Vietnam produced nearly 36 million tons of rice, over half of it in the lush, sprawling Mekong Delta. It also ‘produced’ 7.5 million tons of rice husks.
About half the volume of rice husks is used to feed cattle or make fertilizer or plywood. Some of it fuels brick kilns. However, about half is just wasted.
The redundant rice husks are a headache for many rice millers because they have no place to put it. During the harvest seasons, some pay a lot of money to have the heaps of husks carried to rubbish dumps. Some just dump the rice husks into rivers (which is of course illegal).
Not surprisingly, it has occurred to entrepreneurs and renewable energy experts that rice husks can be used to generate electricity. The experts say that 1.6-2.2kg of rice husk is enough to create 1kWh of power.
Tran Quang Cu of the International Finance Corporation (IFC, an arm of the World Bank) advocates that Vietnam set up medium-sized power plants fueled by rice husks of 160-180 megawatts (MW) in capacity near rice growing areas. By burning 1.5 million tons of rice husks a year, Cu says, Vietnam can produce 1-1.2 terawatt hours of power.
In the Delta, a kilo of rice husks currently costs only 200-300 dong – that is, it’s practically free to anyone who will haul it away. Rice mills in the Mekong Delta are mainly located along rivers so it is convenient to transport rice husks to thermo-power plants.
In Southeast Asia, experimentation with rice husk power plant projects started in the mid 1990s. Two projects implemented in Thailand demonstrated their feasibility. Project developers in Southeast Asia gained confidence by visiting these projects. Today, many more such projects are in various stages of development and implementation.
From the technological perspective, in the last 10 years, most problems have been solved. Today the plants are fully automated and, for well designed plants, the efficiency of the boiler and the overall efficiency of the power plant are very good.
There has also been considerable reduction in the total investment cost, mainly due to the competition of a dozen boiler suppliers who have mastered the technology.
Most plants are much smaller than the power plants suggested by the IFC’s Cu. In Thailand, they range from 22 MW down to two MW. A 50 MW plant was studied, but due to the problem of fuel security, that project did not materialise. A 30 MW power plant was studied in Philippines and it also was abandoned due to fuel collection and transportation issues.
By contrast, an average-sized coal-fired power plant will produce about 600 MW of power.
With advancement in technology, some of the projects produce high quality silicate ash that’s valuable as fertilizer. It is exported to Europe, Japan, Korea and other countries for as much as $400/ton. Some projects focuses more on rice husk ash than power. This solves the ash disposal problem, as rice husk contains up to 20 percent ash.
Vietnam hops on the bandwagon
Nearly a dozen rice husk-fuelled power plants are underway in the Mekong Delta. They include two in An Giang province - one in the Hoa An industrial zone in Cho Moi district and the other in Thoai Son district.
The first plant is built on an 18 hectare lot with 10 MW capacity and total investment of over $10 million by Dong Thanh, a local company. The second plant also has 10 MW capacity and is built by a local firm, with a reported investment of $15 million. These two plants will consume around 240,000 tons of rice husks a year.
In Tien Giang province, the local authorities have approved a 10 MW rice-husk power plant worth $18.6 million.
In Dong Thap province, Duy Phat JS Company is licenced to build a 10 MW factory in Lap Vo district, at a cost of 296 billion dong ($16.4 million).
Kien Giang province is searching for a good place to build an 11 MW factory. By building this factory, the investor aims to earn emissions reductions offsets of over 27,000 tons of CO2 and CH4.
In Can Tho City the Dinh Hai Thermo-power JS Company has built a rice-husk power factory in Tra Noc industrial zone. This company is also cooperating with J-Power (Japan) to build another 10 MW plant in Thot Not district that will use around 80,000 tons of rice husk a year.
J-Power said that if this plant operates successfully, it will joint-venture 10-15 husk-fuelled plants in the Mekong Delta.
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