09:32 | 05/10/2017 Energy
As Vietnam develops its thermal power plant system to meet increasing energy demands, the country faces a new environmental risk arising from the waste generated by those plants.
Burning coal for power results in the production of a variety of solid waste, including coal ash (fly ash and bottom ash) and boiler slag. Under Vietnam’s regulations, boiler slag is defined as unharmful solid waste, but fly ash is listed as “possibly harmful waste”.
Official figures show the 21 thermal power plants across the country generate about 15.8 million tonnes of coal ash and boiler slag, of which only about 5 million tonnes are treated. Without a systematic waste treatment plan, many plants will soon run out of space to store them.
Mong Duong 1 thermal power plant in northeastern Quang Ninh province went into operation at the end of 2015 but is running the risk of closure due to this problem.
The 1,080MW-capacity plant consumes about 3 million tonnes of coal a year and releases 1 million cubic metres of coal ash and boiler slag. Its dumping ground has a storage capacity of 1.25 million cu.m, of which up to 1.8 million have been used. According to EVN GENCO 3, the plant investor, the storage capacity will run out in eight months.
Thermal power plants in the southern province of Tra Vinh are facing the same fate.
Duyen Hai Power Center, comprising four power plants, has dumping grounds of 100 hectares. Nguyen Trung Hoang, vice chairman of the provincial People’s Committee, said the likelihood of it being filled up may happen soon as “the amount of ash and boiler slag are huge”.
Meanwhile, the dumping ground of Cam Pha Thermal Power Plant, also located in Quang Ninh province, is already overflowing, the plant’s deputy director Nguyen Dinh Tuan told the Thanh Nien (Young people) newspaper.
The company had contracts with two enterprises to sell boiler slag as materials to produce cement, but the amount was too small for that purpose.
Tran Van Luong, head of the Industrial Safety Techniques and Environment Agency, admitted that the by-products of coal burning to generate electricity pose a challenge to the environment.
Vietnam will have 12 additional thermal power plants by 2020, which are predicted to generate about 22.6 million tonnes of coal ash and boiler slag each year.
Luong said that a way out of the problem is making use of the waste to produce building materials.
According to Associate Professor Truong Duy Nghia, chairman of Thermo Scientific and Technical Society, coal ash and boiler slag are mainly comprised of metal oxide suitable for producing building materials. “When coal ash and boiler slag are used to produce building materials, the environmental problem is solved,” he said.
In fact, a couple of plants have already done so and attained good result.
Hai Phong Thermal Power Company in the coastal city of Hai Phong has been able to sell a majority of its production residues to companies producing cement and non-fire bricks.
This is why its dumping ground with a capacity to hold 9 million tonnes of waste is never overloaded, said Nguyen Thuong Quang, the company’s director.
“Using coal ash and boiler slag as materials help produce good quality cement and increase profits. In fact, people have made used of this waste to produce cement and non-fire bricks for a long time,” Quang said.
Although the selling price of the waste is not high, only about 10,000-20,000 VND per kilogramme, Quang said the importance was it solved the problem of waste overload.
Company Chairman Tran Van Nam said coal ash and boiler slag should be seen as potential materials, instead of toxic substances.
However, he admitted there were obstacles hindering other power plants from doing what his company was doing, especially in the country’s southern area.
“Unlike in the north, cement and brick producing plants in the south are often far away from thermal power plants. As a result, the consumption of coal ash and boiler slag faces difficulties due to high transportation cost,” he said.
Nam suggested that the State should plan cement and brick producing plants surrounding thermal power plants, in addition to policies to support technology development relating to this issue and tax incentives for the companies involved.
According to Luong from the Industrial Safety Techniques and Environment Agency, there are still other problems, including the lack of national technical regulations on coal ash and boiler slag use for building materials.
At a recent seminar on developing thermal power, a representative of the Ministry of Construction said the ministry is compiling such a document and expects to issue it by early next year, in hopes of overcoming the obstacle.