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Lakvijaya: Poor coal quality a major cause of environment pollution
Lack of attention to the quality of coal has been “a major cause of environmental problems” at the Lakvijaya power plant, the National Audit Office (NAO) says in its recent annual report.
The Norochcholai power plant
The opinion adds weight to conclusions released in May this year by the Industrial Technology Institute (ITI) that sulphur dioxide concentration from unit 1 and 2 of Lakvijaya exceeds the maximum permissible level and that particulate matter concentration from unit 1 also surpasses the maximum permissible level.
When it was measured, the particulate matter concentration from unit 1 was 2398 mg/Nm3. This meant that its stack was emitting 1.8 metric tonnes of fly ash per hour or 45 metric tonnes of fly ash per day.
At the time, however, six fields of the unit 1’s electrostatic precipitator (ESP) and one field of unit 2’s ESP were out of order. The flue gas desulpherizer (FGD) of unit 2 was completely broken.
Sri Lanka has shifted from Indonesian coal to South African, which is more polluting. The ash percentage of Indonesian coal is around seven percent. The South African coal imported to Sri Lanka has about 15 percent, in general. This is considered the upper limit. But a number of shipments brought into Sri Lanka exceed even this and, therefore, fly ash generation has doubled, experts said.
Indonesian coal also has high moisture content (usually between 12 and 14 percent). South African coal moisture is between six and eight percent. Low moisture makes coal pieces break into dust which then gets blown in the wind to villages.
“The time they changed from Indonesia to South Africa is the time the coal dust problem intensified in the village,” one expert said.
There are two side effects of burning coal for electricity production, the NAO says: fly ash and bottom ash. Lakvijaya’s ash disposal yard is around 25 acres in extent. The life expectancy of each 300mw unit of Lakvijaya was 35 years at the planning stage. Assuming all three run at 65 percent efficiency, the quantity of fly and bottom will be 6,405,750 metric tonnes and 1,281,150 metric tonnes, respectively.
About 425,008 metric tonnes of fly ash was sold by Lakvijaya from 2015 to May last year. But a further 443,909 metric tonnes was stored in the ash yard.
At the project planning stage, a mechanism for disposal of fly and bottom ash was described. It has been inadequately implemented because measures to mitigate environmental problems came at a financial cost, the NAO observed. The North Western Provincial Environmental Authority (NWPEA) has failed to continuously monitor the coal power plant’s ambient air quality standards, it noted.
Among other things, the NAO recommends that plant maintenance be carried out to plan; that the wind barrier around the coal yard to prevent dust particles from spreading be widened; and measures to prevent dispersal of ashes already in the yard be taken.
Meanwhile, the coal power plant is once again operating with an environmental protection licence (EPL). The NWPEA renewed it in October 2018 but it lapsed last month.