"If no additional capacity is made, the crucial period will be in 2010 to 2011 during which the reserve level is expected to fall (less) than the minimum reserve level," Transco said in a Powerpoint briefing it provided to the media.
Mindanao has an existing generating capacity of 1,850.4 megawatts (MW) beginning 2008 but the dependable capacity is only 1,520 MW.
"We have to maintain a certain level of reserve capacity for maintenance of transmission lines and power plants," Transco General Santos City chief Manuel Hamoy said.
Peak demand starting 2008 is projected to hit 1,440 MW.
This year, the reserve requirement will only be 22 per cent of the available generating capacity, 1.4 per cent below the minimum reserve requirement, according to Transco.
In addition, existing transmission lines are already fully loaded and may not be able to sustain further generating capacity, the government-owned corporation likewise warned.
The South Cotabato-Cotabato-Sultan Kudarat-Sarangani-General Santos city area (Soccsksargen), which represents District VI of Transco's coverage in Mindanao, now consumes about 150 MW of electricity on a daily basis.
This could increase in the next three years however as several mining firms are expected to increase their power requirement.
Among them is Sagittarius Mines, Inc. (SMI), which is expected to require at least 150 MW when its mining project goes full operational by 2011.
Aside from power supplied by the National Power Corporation (Napocor) Mindanao grid, the Soccskargen area only has 116 MW generating capacity from two diesel-fired power plants located in General Santos City (56.4 MW) and in Alabel, Sarangani (50 MW).
Southern Mindanao, which includes the Cotabato and Davao provinces, has a total peak demand of 526 MW while its total dependable capacity is only 320 MW.
As a result, the region has to "import" 206 MW of its power supply requirement from Napocor, which derives most of its capacity from Northern Mindanao. (Edwin G. Espejo / MindaNews contributor)