The Electricity Generating Authority of Thailand (Egat) plans to open bidding this year on contracts for developing high-voltage transmission lines (HVTL) with a capacity of 500 kilo-voltage worth 157 billion baht.
The bids are due to start this year for 55 contracts, with the rest opening in 2018.
Egat deputy governor Kijja Sripatthangkura said the 55 contracts to open for bids this year are worth roughly 60 million baht of investment budget.
He said the development of Egat's HVTL are to replace existing lines that have been used for more than 40 years. Some of the bids are to develop extension lines to help secure the country's power supply at a time when demand is rising.
The bids will be open to all Thai and international companies.
The project to develop the HVTL is a part of Egat's total capital expenditure of 600 billion baht over the next 10 years, Mr Kijja said.
Most of the HVTL to be bid are in the South and Northeast, especially the former where growing tourism has increased power demand. The development of two new coal-fired power plants in the South have been delayed for a few years because of strong opposition from local villagers and environmental activists.
He said most of the bids this year are to develop HVTL to transmit power from the central region to the South, starting from Ratchaburi and ranging to Prachuap Khiri Khan's Bang Saphan district.
Another grouping of HVTL from Bang Saphan to Surat Thani and Phuket will develop new transmission lines to supply power to the South.
The HVTL to the South is worth 63.2 billion baht, spans 800 KM and is due to start operation in 2019.
Mr Kijja said Egat also plans to develop a new HVTL extension to the deep South, running from Surat Thani to Songkhla province, worth 35.4 billion baht. That project is expected to receive cabinet approval by next month, with bids open to develop it due in 2019.
Power demand in the deep South averages 5% annual growth in part because of tourism around the Andaman Sea.
He said another project worth 94 billion baht is to develop 1,000km of HVTL in the Northeast to secure the power supply in the region and prepare for transmission of additional power from hydropower plants in Laos.
The new HVTL are also expected to help transmit power generated from new renewable power projects in the Northeast, where several biomass, solar and wind farm projects are due to be developed.