BANGKOK, April 5 (Reuters) - Soaring temperatures could send Thailand's electricity demand to a record high on Friday just as imports of natural gas from Myanmar fall, raising the risk that industry and other power cutbacks will not be enough to prevent a shortfall.
The temperature in Bangkok is forecast to go above 40 Celsius (104 Fahrenheit) on Friday. This is the hottest time of the year in the Thai capital but 37C or 38C is more common.
A likely surge in air conditioner use comes as about 15 percent of Thailand's electricity output will be affected from midday (0500 GMT) on Friday, when maintenance at a Myanmar field cut supplies of gas used to fuel power plants.
The Thai government has persuaded nearly 100 large factories to stop operations or cut production to save energy.
A Thai unit of Toyota Motor Corp will halt three plants on Friday and top Thai industrial conglomerate Siam Cement has agreed to adjust production in such a way as to reduce power use by 20 percent, for example by taking machinery out for maintenance.
"About 97 factories operating in the state industrial parks have agreed to join the energy-saving schemes," said Jakkarat Lertopas, deputy governor of the state-run Industrial Estate Authority of Thailand (IEAT).
"That will help save about 108 MW of electricity," he said.
The government has also asked the public to cooperate by setting air conditioners at a higher temperature than normal.
Domestic demand is expected to hit a record on Friday of 26,600 MW due to the hot weather, Suthat Patmasiriwat, governor of the Electricity Generating Authority of Thailand, said. That compares with the previous peak on March 28 of 26,430 MW.
The Yadana gas field in Myanmar will be shut down for maintenance from April 5 to 14. The field, operated by France's Total, needs additional maintenance this year because of problems with rigs.
During the maintenance period, Myanmar will stop supplying natural gas from Yadana but also from the nearby Yetagun field. Gas from the two fields has to be mixed together for export to Thailand to make it suitable for use in Thai power plants.
The shutdown will lead to a drop in gas supply of 1.1 billion cubic feet per day (cfd), which will affect power output at six power plants with a capacity of 4,100 megawatts, data from the state generator shows.
Three of the six plants, including Ratchaburi Electricity Generating Co, have shifted to run on bunker oil and diesel, while Thailand is seeking additional power supplies from hydroelectric plants in Laos as well as from Malaysia.
IRPC Pcl, a petrochemical and refining affiliate of state-run PTT Pcl, will supply power to the national grid from a plant whose output is normally for its own use.
Thailand uses natural gas for almost 70 percent of its power generation and one-fifth is imported from Myanmar. It also uses gas in petrochemical plants, households and vehicles.
Friday should see the peak in demand. It typically drops over the weekend and Monday is a holiday. Electricity demand is expected to be 25,920-25,950 MW on April 9 and 10, according to EGAT.
The long holiday weekend for Songkran, the Thai New Year, runs from April 13-16 and is also typically a time when power demand falls. (Additional reporting by Pisit Changplayngam; Editing by Alan Raybould and Michael Urquhart)