The Mae Moh power plant, with its 2,625 megawatt (MW) installation capacity,
is the largest thermal lignite1
-fired power plant in Thailand and in Southeast Asia,
meeting approximately 18 per cent of the national power demand. There have been
substantial environmental and social concerns regarding the operation of the plant
especially after the first incidence of air pollution caused by it in 1992 when the
expansion of the plant reached the capacity of 2,025 MW – apparently hitting the
ecological carrying limit of the surrounding environment. An all-time high reading of
the hourly average ground level of ambient sulfur dioxide (SO2) concentration of 3,418
micrograms per cubic meter (µg/m3
) was observed as compared with the then hourly
average Thai standard of 780 µg/m3
.